Contraception: Hormonal and Intrauterine Devices

Clinical Snapshot

Contraception is the deliberate prevention of pregnancy, and hormonal and intrauterine methods are the most effective reversible options available. Combined hormonal contraceptives (pill, patch, or ring) pair an estrogen with a progestin and work mainly by suppressing ovulation; progestin-only methods (pill, injection, implant, or hormonal intrauterine system) avoid estrogen entirely and are appropriate whenever estrogen is contraindicated, poorly tolerated, or simply not preferred; and the copper intrauterine device is a highly effective, fully non-hormonal option that also works as emergency contraception.^[1] Method choice is a patient-centred decision that weighs effectiveness, individual medical eligibility (chiefly venous thromboembolism and cardiovascular risk with estrogen-containing methods), route and regimen preference, non-contraceptive benefits, and the patient's own plans for future fertility — and pharmacists are frequently the first point of contact for missed-dose questions, drug-interaction concerns, and adverse-effect troubleshooting that ultimately determine whether a method is continued or abandoned.

Recognize the Condition

How this chapter is organized

Unlike most chapters in this reference, there is no disease to recognize here — the clinical task is method selection, initiation, and troubleshooting for a patient who needs pregnancy prevention. Typical encounters include a patient starting contraception for the first time, a patient switching methods because of side effects or a change in medical eligibility (a new migraine with aura, a new VTE, or a desire for pregnancy), a postpartum or postabortion patient, or a patient reporting a missed dose, a suspected drug interaction, or unscheduled bleeding on an existing method.

The three method classes covered in this chapter

Combined hormonal contraceptives

Pill, transdermal patch, or vaginal ring — all pair an estrogen (almost always ethinyl estradiol, or estetrol in one newer product) with a progestin, and require an eligibility check for estrogen-specific contraindications before use.

Progestin-only contraceptives

Pill, injection (DMPA), or subdermal implant — no estrogen at all, so far fewer absolute contraindications; the trade-off is a narrower dosing-window tolerance for the pill and, for DMPA, a delay in the return of fertility after discontinuation.

Intrauterine devices

Hormonal (levonorgestrel-releasing) or copper — inserted once and left in place for years, the most effective reversible methods available because they remove any dependence on the patient remembering to do anything.

Risk Factors

The following factors change — or eliminate — eligibility for estrogen-containing (combined hormonal) contraception specifically; progestin-only methods and the copper IUD remain appropriate options for almost all of them.^[2]

Current pregnancy.
Current or past venous thromboembolism or pulmonary embolism, or a known thrombogenic mutation (factor V Leiden, prothrombin gene mutation) or protein C, protein S, or antithrombin deficiency.
Migraine with aura, at any age.
Age over 35 and smoking 15 or more cigarettes per day.
Uncontrolled hypertension, or a systolic BP ≥160 mmHg or diastolic ≥100 mmHg.
Diabetes with microvascular complications (nephropathy, retinopathy, neuropathy) or other vascular disease.
Current or past breast cancer or another hormone-sensitive cancer.
Complicated valvular heart disease, ischemic heart disease, or history of stroke.
Severe cirrhosis or an active liver tumour.
Fewer than 6 weeks postpartum, particularly if breastfeeding.
Obesity — independently raises VTE risk with estrogen-containing methods, and may reduce transdermal patch efficacy at higher body weight.
Immobility, recent major surgery, or another transient period of elevated VTE risk.
Use of an enzyme-inducing medication that can reduce hormonal contraceptive effectiveness.

Red Flags & Refer

The mnemonic ACHES covers the classic warning signs of a serious vascular event in a patient using combined hormonal contraception — any one of these needs immediate medical assessment, not reassurance.^[3]

A — severe Abdominal pain (possible hepatic, gallbladder, or thrombotic event).
C — Chest pain, shortness of breath, or coughing blood (possible myocardial infarction or pulmonary embolism).
H — severe Headache that is new, different from usual, or worsening (possible stroke or cerebral venous thrombosis).
E — Eye problems (vision loss, blurring, double vision) or slurred speech (possible stroke or retinal artery thrombosis).
S — Severe leg pain or swelling, especially the calf or thigh (possible deep vein thrombosis).
Jaundice, right-upper-quadrant pain, or a new palpable liver mass in a patient on combined hormonal contraception — evaluate for hepatic adenoma or cholestasis.
Fever, pelvic pain, and abnormal discharge in a patient with an IUD in place — evaluate for pelvic inflammatory disease; the device does not necessarily need to be removed for treatment to succeed.
Inability to feel or visualize IUD strings, or strings that feel different than before — assess for expulsion, perforation, or malposition rather than assuming the device is still correctly placed.
A positive pregnancy test with an IUD in place — assess urgently for ectopic pregnancy.

Assessment & Diagnosis

History

Full medical, surgical, and gynecologic history, including migraine (and whether it includes aura), VTE/thrombophilia, hypertension, diabetes, liver disease, and any hormone-sensitive cancer.
Smoking status and, if applicable, cigarettes per day.
Breastfeeding status and time since delivery.
All current medications and natural health products, specifically screening for enzyme-inducing agents and GLP-1 receptor agonists.
Menstrual history, and whether heavy menstrual bleeding, dysmenorrhea, endometriosis, acne, or PMDD symptoms exist that a chosen method might also help manage.
Prior contraceptive methods tried, reason for discontinuation, and adherence pattern or risk of nonadherence.
Desire and timeline for future fertility.

Examination and investigations

Pregnancy test whenever there is any uncertainty about current pregnancy status.
Weight.
Blood pressure — required before starting a combined hormonal method.
Bimanual examination and cervical inspection before IUD insertion.
STI screening before IUD insertion when risk factors are present; insertion should not otherwise be delayed pending results in a low-risk patient.

When testing is not required

Routine STI screening, Pap testing, or a pelvic examination are not required before starting the pill, patch, ring, implant, or DMPA in a patient without specific risk factors or symptoms — initiation should not be delayed to obtain them.^[4]

Treatment Targets

Prevent unintended pregnancy, matched to the patient's own effectiveness expectations and tolerance for a user-dependent method versus a fit-and-forget method.
Select a method the patient can and will use correctly and consistently — the most effective method on paper provides no benefit if it is discontinued or used incorrectly.
Avoid estrogen-containing methods in anyone with a contraindication to estrogen.
Deliver a relevant non-contraceptive benefit — bleeding control, acne, dysmenorrhea, or endometriosis symptom control — when it matters to the patient's other goals.
Preserve a return to fertility on a timeline that matches the patient's own plans.
Address STI protection separately, since no hormonal or intrauterine method provides any protection against sexually transmitted infection.

Choose Initial Treatment

Direct treatment rule

Step 1 — screen for estrogen eligibility

No contraindication to estrogen a combined hormonal method (pill, patch, or ring) is a reasonable first-line option; for most patients starting a pill, use a monophasic levonorgestrel/ethinyl estradiol product first, given its comparatively low VTE signal and long track record.

Any absolute contraindication to estrogen present (current/past VTE, migraine with aura, uncontrolled hypertension, age over 35 with heavy smoking, active breast cancer, complicated valvular or ischemic heart disease, severe cirrhosis or liver tumour, or fewer than 6 weeks postpartum) do not prescribe a combined pill, patch, or ring — move to a progestin-only method or an IUD instead.^[2]

Step 2 — offer the most effective option regardless of the branch above

Patient has no strong method preference, or wants the highest effectiveness with the least ongoing effort lead with a long-acting reversible method — the etonogestrel implant, a levonorgestrel intrauterine system, or the copper IUD — all are appropriate first-line, including for nulliparous adolescents, and none depend on daily, weekly, or monthly patient action.^[5]

Patient prefers a self-administered method they can stop themselves select from the eligible combined hormonal options (Step 1) or a progestin-only pill or DMPA injection.

Step 3 — adjust for interacting medications

Patient uses a long-term enzyme-inducing medication (carbamazepine, phenytoin, phenobarbital, primidone, oxcarbazepine, eslicarbazepine, rifampin, or rifabutin) or St. John's wort avoid the combined pill/patch/ring, the progestin-only pill, and the implant — their effectiveness is reduced; use DMPA, a copper IUD, or an LNG-IUS instead, none of which depend on hepatic enzyme metabolism for efficacy.

Step 4 — choose an initiation strategy

Use a quick start (start the method the same day as the visit, after a negative pregnancy test, with backup contraception for the first 7 days) for essentially all patients — it is preferred over a traditional Sunday-start or first-day-of-period start because it removes the delay in which an unintended pregnancy can occur, and it does not reduce method continuation or safety.^[3]

Non-Pharmacologic Treatment

No hormonal or intrauterine method protects against sexually transmitted infection — counsel correct, consistent external condom use for STI protection regardless of the primary contraceptive method chosen.^[1]
Correct-use counselling is method-specific: take the pill at the same time daily; apply the patch to dry, intact skin of the buttock, abdomen, upper outer arm, or upper torso and rotate the site each week; insert the ring so it is comfortable (exact position does not affect efficacy) and leave it in place continuously for 3 weeks.
Offer a quick-start initiation (start today, same visit) rather than asking the patient to wait for their next period or a Sunday, and prescribe up to a year's supply where feasible — both measures reduce gaps in coverage and improve continuation.
Discuss long-acting reversible contraception (implant, LNG-IUS, copper IUD) proactively with adolescents and any patient at higher risk of inconsistent use — these methods are safe in nulliparous patients of any age and do not require ongoing patient action.
For patients on long-term DMPA, discuss bone mineralization, particularly if the patient has a low body weight or other osteoporosis risk factors — this is a conversation, not a reason to withhold the method.
Extended or continuous combined hormonal regimens (no hormone-free interval, or a hormone-free interval no longer than 7 days) reduce total bleeding days and can improve dysmenorrhea, endometriosis-related pain, and cyclical symptoms such as headache and bloating; counsel that unscheduled spotting is the main trade-off, and that continuous use removes the withdrawal bleed that would otherwise signal a missed period.
Patients with a known Zika virus infection or exposure should use condoms or abstain from vaginal intercourse for 6 months before attempting conception, or for the duration of pregnancy, since Zika can be transmitted through semen.
Reassure patients that combined hormonal contraceptives do not need a backup method when taking antimicrobials that are not enzyme inducers — this includes penicillins, tetracyclines, macrolides, fluoroquinolones, and imidazole antifungals; the belief that all antibiotics reduce contraceptive efficacy is a persistent myth not supported by current evidence, though vomiting or diarrhea from any illness or antibiotic side effect can itself reduce absorption and does warrant backup precautions.^[3]

Pharmacologic Treatment Options

Drug / intervention	Role	Dose / use	Important adverse effects	Teaching points
Levonorgestrel/Ethinyl estradiol Preferred	First-choice combined pill for most patients	1 tablet PO daily x21 active days, then 7 placebo days (28-day pack)	Breakthrough bleeding, nausea, breast tenderness, headache	Start with a quick start at the same-day visit; lowest documented VTE signal among the progestins in this class.
Drospirenone/Ethinyl estradiol Alternative	Combined pill when acne or PMDD benefit is desired	1 tablet PO daily; 21-24 active days depending on product, then 4-7 placebo days	Hyperkalemia risk, breakthrough bleeding, nausea	Check potassium after the first cycle if the patient also takes an ACE inhibitor, ARB, potassium-sparing diuretic, or NSAID; higher VTE signal than levonorgestrel-containing pills.
Norelgestromin/Ethinyl estradiol patch Alternative	Weekly transdermal option	1 patch weekly x3 weeks, then 1 patch-free week	Application-site reaction, breast discomfort	May be less effective at body weight 90 kg or greater; off less than 48 hours, reapply the same patch; off 48 hours or more, apply a new patch and use backup contraception for 7 days.
Ethinyl estradiol/Etonogestrel ring Alternative	Monthly self-inserted vaginal ring	Insert, wear continuously x3 weeks, remove x1 week	Vaginal discharge/irritation, headache	Out less than 48 hours, rinse and reinsert the same ring; out 48 hours or more, insert a new ring and use backup contraception for 7 days.
Norethindrone Special situation	Progestin-only pill when estrogen is contraindicated	0.35 mg PO once daily, continuously, no hormone-free days	Irregular bleeding, headache	More than 3 hours late counts as a missed dose — take as soon as remembered and use backup contraception for 48 hours.
Drospirenone (progestin-only) Special situation	Progestin-only pill with a wider dosing window	1 tablet PO daily: 24 active tablets, then 4 inactive tablets	Hyperkalemia risk, breakthrough bleeding	More forgiving (about 24-hour) timing window than norethindrone; 2 or more missed active tablets needs backup contraception for 7 days.
Medroxyprogesterone acetate Special situation	Injectable option, every 12-13 weeks	150 mg IM (or 104 mg SC) every 12-13 weeks	Irregular bleeding progressing to amenorrhea, weight change, reversible bone mineral density loss	Re-inject by 13 weeks; if delayed, exclude pregnancy and use backup contraception for 7 days; discuss bone health with long-term use.
Etonogestrel implant Preferred	Subdermal LARC, 3-year duration	1 rod inserted subdermally; replace by 3 years	Irregular bleeding, amenorrhea, insertion-site issues	Use backup contraception for 7 days after insertion unless inserted within the first 5 days of the cycle or immediately postpartum/postabortion.
Levonorgestrel intrauterine system Preferred	Hormonal IUD, 5- to 8-year LARC	Mirena 52 mg (8 years) or Kyleena 19.5 mg (5 years), inserted intrauterine	Spotting for the first 3-6 months, expulsion, rare perforation	Backup contraception for 7 days unless inserted within 7 days of menses onset; also reduces menstrual blood loss and dysmenorrhea.
Copper intrauterine device Preferred	Non-hormonal IUD, up to 10-year LARC; also emergency contraception	Inserted intrauterine; effective immediately	Heavier/longer menses, cramping, rare expulsion or perforation	The only IUD effective as emergency contraception, up to 7 days after unprotected intercourse; no hormonal adverse effects.

Special Populations

Pregnancy

No hormonal or intrauterine contraceptive method is used during an established, desired pregnancy. If pregnancy is confirmed while a method is in place, discontinue combined hormonal methods; for an IUD, assess for ectopic pregnancy and, if the pregnancy is intrauterine and the strings are visible, removal is generally recommended to reduce the risk of miscarriage and infection. Epidemiologic study has not found an increased risk of birth defects with inadvertent early-pregnancy exposure to any of these methods.

Breastfeeding and the postpartum period

Progestin-only methods (pill, DMPA, implant, LNG-IUS) are recommended for postpartum patients regardless of breastfeeding status, given their lower thromboembolism risk in the puerperium and neutral effect on milk supply, and can be started immediately after delivery; the drospirenone-only pill is the one exception, best avoided immediately postpartum until more safety data accumulate. Combined hormonal methods should be avoided for the first 6 weeks postpartum in anyone breastfeeding or with a VTE risk factor, and can generally be started at 3 weeks postpartum in patients who are not breastfeeding.^[3] An IUD may be inserted immediately postpartum (vaginally or at cesarean section) or after a first- or second-trimester abortion, though expulsion and perforation rates are somewhat higher with immediate postpartum insertion than with insertion at the 6-week visit; ensure good fundal placement, which can be technically more difficult in the larger immediate postpartum uterus.^[6]

Adolescents

LARC methods (implant, LNG-IUS, copper IUD) are the preferred first-line option in adolescents at high risk of contraceptive failure from inconsistent use, and are safe in nulliparous adolescents of any age.

Obesity

Combined hormonal methods remain appropriate in most patients with obesity, but obesity is an independent VTE risk factor that should be weighed alongside other risk factors, and the transdermal patch may be less effective at body weight 90 kg or greater — consider an alternative combined method or a LARC option in this situation.

HIV

IUDs do not increase the risk of acquiring HIV compared with no contraceptive method, and DMPA and the LNG-IUS maintain contraceptive efficacy during antiretroviral therapy; some antiretrovirals can interact with combined hormonal pills, so review the regimen before prescribing. Spermicide containing nonoxynol-9 provides no protection against HIV regardless of formulation or dose, and consistent external condom use remains essential for HIV and other STI protection alongside any contraceptive method chosen.

Renal and hepatic impairment

Active liver disease, cholestasis, and liver tumours are contraindications to estrogen-containing methods; progestin-only pills and DMPA are also relatively contraindicated in significant hepatic impairment given hepatic metabolism, while the copper IUD and LNG-IUS are reasonable options since they act locally. The drospirenone-containing progestin-only pill is contraindicated in renal impairment given its antimineralocorticoid activity and hyperkalemia risk.

Mood disorders

Current eligibility criteria do not recommend against hormonal contraceptive use in patients with a history of depression or another mood disorder; monitor for new or worsening depressive symptoms after starting any hormonal method, particularly in adolescents.

Monitoring & Follow-Up

Recheck blood pressure and reassess tolerability within the first few months of starting a combined hormonal method, then at routine intervals thereafter.
Reassess adherence, side effects, and satisfaction at each visit — the best method is the one the patient will actually continue to use correctly.
For DMPA, track the reinjection date and reinject no later than 13 weeks after the previous injection; discuss bone health with long-term (multi-year) use.
For an IUD, teach the patient to check for the strings periodically and to report any change; a routine follow-up visit is reasonable after the first menses or within a few months of insertion to confirm correct placement.
Reassure patients that unscheduled bleeding and spotting are common in the first 3 to 6 months of any new hormonal method and typically improve with continued use.
For a new, persistent, or worsening headache, reassess whether it is the self-limiting first-cycle type or a red-flag symptom requiring urgent evaluation.

Treatment Failure / Next Step

Confirm the method is being used correctly and consistently — timing of the pill, patch/ring change schedule, DMPA reinjection interval, or (for an IUD) that strings are still visualized — before assuming the method itself has failed.
Screen for an interacting medication (enzyme inducer, or a GLP-1 agonist during dose escalation) or a recent illness with vomiting/diarrhea that could have reduced absorption.
For persistent or new-onset breakthrough bleeding on a combined pill, increase to a formulation with up to 35 mcg ethinyl estradiol or change the progestin type; for bleeding on a continuous regimen, stop active pills for 3 to 4 days, then resume.
For persistent LNG-IUS-related spotting beyond the first few months, a short course of NSAIDs or tranexamic acid around the expected bleeding days is a reasonable adjunct, though evidence for either is mixed; rule out malposition or expulsion first if bleeding is new or has changed pattern.
For new-onset amenorrhea, rule out pregnancy before reassuring the patient that amenorrhea is an expected and common effect of several methods (LNG-IUS, DMPA, implant, continuous-regimen combined pills, continuous ring use).
For persistent or bothersome bleeding after 3 to 6 months despite reassurance and first-line management, or for any adverse effect that is unacceptable to the patient, switch methods rather than continuing to manage around it — discontinuation of an unwanted method is itself a leading cause of unintended pregnancy.
For suspected IUD expulsion or malposition (cannot visualize strings, strings feel different, new pain, or bleeding), confirm position with ultrasound before assuming ongoing contraceptive protection.

Common Errors to Avoid

Prescribing a combined pill, patch, or ring to a patient with migraine with aura — this is an absolute contraindication because of stroke risk, not a relative caution.
Telling a patient that any antibiotic requires backup contraception — only rifampin and rifabutin (and the anticonvulsant/antiepileptic enzyme inducers) meaningfully reduce hormonal contraceptive effectiveness; other antimicrobials do not.
Delaying LARC insertion or hormonal method initiation to obtain a Pap test, pelvic examination, or routine STI screening in a patient without specific risk factors.
Missing the GLP-1 agonist interaction — tirzepatide can reduce oral contraceptive absorption during dose escalation and needs backup contraception counselling.
Assuming a single missed combined pill requires backup contraception — it does not; backup is needed only for 2 or more missed pills, or for a norethindrone progestin-only pill taken more than 3 hours late.
Treating expected, long-term-monitored DMPA-associated bone mineral density change as itself a reason to withhold or stop the method rather than a factor to discuss and monitor.
Confusing the levonorgestrel-only emergency contraceptive pill (Plan B) with the levonorgestrel intrauterine system (Mirena/Kyleena) — they are entirely different formulations, doses, and use cases.
Overlooking that a copper IUD is itself a highly effective emergency contraceptive option when inserted within 7 days of unprotected intercourse.
Failing to offer LARC options to nulliparous or adolescent patients out of an outdated assumption that these methods are unsuitable in that population.

Clinical Decision Algorithm

Method selection framework

Patient requests contraception or contraceptive counselling

Exclude current pregnancy; take a full medical, gynecologic, and medication history, and check blood pressure

Absolute contraindication to estrogen present (current/past VTE, migraine with aura, smoking ≥15 cigarettes/day age ≥35, uncontrolled hypertension, active breast cancer, complicated valvular/ischemic heart disease, severe cirrhosis/liver tumour, under 6 wk postpartum)

Do not prescribe a combined pill, patch, or ring

Offer the etonogestrel implant (Nexplanon), an LNG-IUS (Mirena/Kyleena), a copper IUD, DMPA (Depo-Provera), or a progestin-only pill (norethindrone or drospirenone)^[2]

No contraindication to estrogen

Combined hormonal contraceptive eligible — pill, patch, or ring all reasonable

For most patients, start a monophasic levonorgestrel/ethinyl estradiol pill (e.g., Min-Ovral) first — lowest documented VTE signal among the progestins

Consider a drospirenone- or estetrol-containing pill, the patch, or the ring instead when acne/PMDD benefit, adherence pattern, or patient preference favours a different formulation

Discuss LARC (implant, LNG-IUS, copper IUD) with every patient regardless of the branch above — highest effectiveness, least user-dependent, appropriate first-line for essentially all patients including nulliparous adolescents^[5]

Missed or interrupted combined hormonal method

Patient reports a missed pill, a detached patch, or an expelled/removed ring

Combined pill — 1 pill missed, any week

Take the missed pill as soon as remembered, continue the rest of the pack on schedule, no backup contraception needed

Combined pill — 2 or more pills missed

Take only the most recently missed pill now, discard the others, continue the pack, and use backup contraception (or abstain) for 7 days; if missed in week 1 with unprotected sex in the preceding 5 days, consider emergency contraception; if missed in week 3, skip the hormone-free interval and start the next pack immediately

Patch off or ring out

Off/out less than 48 hours: reapply the same patch or reinsert the same ring immediately, no backup needed

Off/out 48 hours or more: apply a new patch or insert a new ring immediately (this becomes the new change day) and use backup contraception for 7 days

Progestin-only pill taken late or missed

Progestin-only pill (POP) taken late or missed

Norethindrone (Jencycla) — traditional POP, narrow window

More than 3 hours late, or any missed dose: take as soon as remembered and use backup contraception for 48 hours

Drospirenone (Slynd) — wider 24-hour window

1 active tablet missed, less than 24 hours late: take as soon as remembered, no backup needed

2 or more active tablets missed, or more than 24 hours late: take the most recently missed tablet now and use backup contraception for 7 days

Suspected reduced efficacy from an interacting medication

Patient is using an enzyme-inducing medication (carbamazepine, phenytoin, phenobarbital, primidone, oxcarbazepine, eslicarbazepine, rifampin, rifabutin, St. John's wort) or a GLP-1 agonist with delayed gastric emptying (tirzepatide)

Short-term inducer use (≤2 months) and patient wants to continue a combined pill

Use backup barrier contraception for the duration; a specialist-directed continuous or tricycling regimen with at least 30 mcg ethinyl estradiol is an off-label option — do not use this approach with rifampin or rifabutin

Long-term inducer use, or rifampin/rifabutin at any duration

Switch to a method not affected by enzyme induction — DMPA, a copper IUD, or an LNG-IUS

Tirzepatide, during initiation or after each dose increase

Use backup barrier contraception for 4 weeks after initiation and after each dose increase, or switch to a non-oral method^[7]

Drug Tables

How to use this table: Doses are adult doses for patients of reproductive age; confirm patient-specific eligibility against the medical eligibility criteria above before prescribing. Select any drug name to open its complete Pharmasist Drug Database page.

Combined oral contraceptives — monophasic

All products in this class pair an estrogen with a single, constant progestin dose across the pack. Absolute contraindications common to every product in this class: current or past VTE/PE, known thrombophilia, migraine with aura, age over 35 with heavy smoking, uncontrolled hypertension, current or past breast cancer, complicated valvular or ischemic heart disease, stroke history, severe cirrhosis or liver tumour, and fewer than 6 weeks postpartum. Common class-wide adverse effects: breakthrough bleeding/spotting, nausea, bloating, breast tenderness, headache, and mood change — watch for the ACHES warning signs of a serious vascular event. Common class-wide interactions: enzyme-inducing anticonvulsants, rifampin, rifabutin, and St. John's wort reduce effectiveness; tirzepatide may reduce absorption during dose escalation.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Levonorgestrel/Ethinyl estradiol 0.15 mg/30 mcg	Brand examples: Min-Ovral, Portia, Ovima Regimen: 1 tablet PO daily x21 active days, then 7 placebo/hormone-free days	See class note above.	See class note above.	Preferred first-choice COC for most patients — longest track record and comparatively lowest VTE signal among the progestins in this class.
Levonorgestrel/Ethinyl estradiol 0.1 mg/20 mcg	Brand examples: Alesse, Alysena, Aviane, Laylaa Regimen: 1 tablet PO daily x21 active days, then 7 placebo days	See class note above; lower-estrogen-dose products may have more breakthrough bleeding.	See class note above.	Lower-dose alternative within the same progestin/estrogen pairing.
Norethindrone/Ethinyl estradiol 1 mg/35 mcg	Brand examples: Brevicon 1/35, Select 1/35 Regimen: 1 tablet PO daily x21 active days, then 7 placebo days	See class note above.	See class note above.	Alternative progestin choice to levonorgestrel; norethindrone-containing pills are also considered comparatively lower VTE risk.
Norethindrone/Ethinyl estradiol 0.5 mg/35 mcg	Brand: Brevicon 0.5/35 Regimen: 1 tablet PO daily x21 active days, then 7 placebo days	See class note above.	See class note above.	Lower progestin-dose variant of the same pairing.
Desogestrel/Ethinyl estradiol 0.15 mg/30 mcg	Brand examples: Marvelon, Apri, Freya, Miley, Mirvala Regimen: 1 tablet PO daily x21 active days, then 7 placebo days	See class note above.	See class note above.	Third-generation progestin, less androgenic — a reasonable option when acne or hirsutism is a concern, though third-generation progestins carry a comparatively higher VTE signal than levonorgestrel.
Drospirenone/Ethinyl estradiol 3 mg/30 mcg	Brand: Yasmin, Zamine Regimen: 1 tablet PO daily x21 active days, then 7 placebo days	See class note above, plus hyperkalemia in patients predisposed to elevated potassium.	See class note above, plus additive hyperkalemia risk with ACE inhibitors, ARBs, potassium-sparing diuretics, and NSAIDs — check potassium after the first cycle in these patients.	Antimineralocorticoid activity related to spironolactone; also indicated for acne. Comparatively higher VTE signal than levonorgestrel-containing pills.
Drospirenone/Ethinyl estradiol 3 mg/20 mcg	Brand: Yaz, Mya Regimen: 1 tablet PO daily x24 active days, then 4 placebo days	Same as above.	Same as above.	Lower-estrogen-dose variant; also indicated for acne.
Drospirenone/Ethinyl estradiol/Levomefolate calcium 3 mg/20 mcg/0.451 mg	Brand: Yaz Plus Regimen: 1 tablet PO daily, all 28 days	Same as the drospirenone/ethinyl estradiol products.	Same as above.	The last 4 tablets in the pack contain levomefolate calcium (folate) only, to raise folate status in case of an unplanned pregnancy conceived shortly after stopping; also indicated for acne.
Ethinyl estradiol/Norethindrone acetate 10 mcg/1 mg	Brand: Lolo Regimen: 1 tablet PO daily x24 active days, then 4 placebo days	Same class-wide profile; ultra-low estrogen dose reduces some estrogenic effects (bloating, breast tenderness) but may increase breakthrough bleeding.	See class note above.	The lowest-estrogen-dose COC available.
Estetrol/Drospirenone 15 mg/3 mg	Brand: Nextstellis Regimen: 1 tablet PO daily x24 active days, then 4 placebo days	Similar profile to other drospirenone-containing pills; estetrol is not significantly metabolized by CYP450 enzymes.	Fewer expected CYP450-mediated interactions than ethinyl estradiol-based products, though data are still accumulating; the enzyme-inducer caution above still applies.	Newer natural-estrogen (estetrol, E4) product; early data suggest a lower thrombotic signal than ethinyl estradiol-based pills, but long-term VTE safety data are still accumulating — do not treat as free of VTE risk.

Combined oral contraceptives — extended/continuous cycle

Same estrogen/progestin pairing and contraindications as the equivalent monophasic product, packaged for a longer active-tablet run to reduce the number of withdrawal bleeds per year.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Levonorgestrel/Ethinyl estradiol 0.15 mg/30 mcg, 3-month pack	Brand examples: Seasonale, Seasonique, Indayo Regimen: 1 tablet PO daily x84 active days, then a 7-day interval	Same as the monophasic product; unscheduled bleeding is more common than with a 28-day cycle.	Same as the monophasic product.	Packaged as 84 active tablets plus a 7-day hormone-free or ultra-low-estrogen interval, for 4 withdrawal bleeds per year instead of 13.

Transdermal patch

Drug	Dosage	Adverse effects	Drug interactions	Comments
Norelgestromin/Ethinyl estradiol patch	Brand: Evra Regimen: 1 patch weekly x3 weeks, then 1 patch-free week	Application-site skin reaction, breast discomfort (more common than with COC in the first 2 months), headache, nausea, dysmenorrhea; detachment occurs in a small proportion of cycles.	Same enzyme-inducer interactions as combined pills.	May be less effective at body weight 90 kg or greater. If a patch has been off less than 48 hours, apply a new patch immediately and continue the original schedule; if off 48 hours or more, apply a new patch immediately (this becomes the new patch-change day) and use backup contraception for 7 days.

Vaginal ring

Drug	Dosage	Adverse effects	Drug interactions	Comments
Ethinyl estradiol/Etonogestrel ring	Brand examples: NuvaRing, Haloette Regimen: Insert x3 weeks, remove x1 week, per cycle	Vaginal discomfort, vaginitis, headache, leukorrhea, decreased libido, nausea, breast tenderness.	Same enzyme-inducer interactions as combined pills; vaginal antifungals, diaphragms, or cervical caps should not be relied on as a backup method with the ring in place.	Insert and leave in place continuously for 3 weeks, then remove for a 1-week ring-free interval; a reusable version can be used continuously for up to 1 year (13 cycles) on the same 3-weeks-in/1-week-out pattern. If out less than 48 hours, rinse and reinsert the same ring immediately, no backup needed; if out 48 hours or more, insert a new ring immediately and use backup contraception for 7 days.
Segesterone acetate/Ethinyl estradiol reusable ring	Brand: Ringza Regimen: Insert x3 weeks, remove x1 week, reuse the same ring for up to 13 cycles	Similar to the etonogestrel-containing ring.	Same enzyme-inducer interactions as combined pills.	Patient-inserted and -removed; the same ring is washed and reused for up to 1 year (13 cycles) on a 3-weeks-in/1-week-out schedule, reducing the number of pharmacy/clinic visits needed per year.

Progestin-only pills

No estrogen, so the absolute contraindications above (VTE, migraine with aura, smoking-plus-age, uncontrolled hypertension, valvular/ischemic heart disease, severe cirrhosis/liver tumour) largely do not apply; the trade-off is a narrower or more product-specific missed-dose window.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Norethindrone 0.35 mg	Brand examples: Jencycla, Movisse, Maeve Regimen: 1 tablet PO daily, continuously, no hormone-free days	Irregular/breakthrough bleeding (most common in the first few months), headache, breast tenderness, nausea, mood change.	Same enzyme-inducer interactions as combined pills; tirzepatide caution during dose escalation.	Traditional POP — the mucus-thickening effect declines within a few hours of the scheduled dose, so a dose more than 3 hours late is treated as a missed dose: take it as soon as remembered and use backup contraception for 48 hours.
Drospirenone 4 mg	Brand: Slynd Regimen: 1 tablet PO daily: 24 active tablets, then 4 inactive tablets	Breast tenderness, mood change, weight gain, headache, menstrual irregularity, amenorrhea; hyperkalemia and hyperglycemia have also been reported.	Same enzyme-inducer interactions as combined pills, plus additive hyperkalemia risk with ACE inhibitors, ARBs, potassium-sparing diuretics, and NSAIDs.	Wider effective dosing window (about 24 hours) than norethindrone. If 2 or more active tablets are missed, take the most recently missed tablet as soon as possible and use backup contraception for 7 days. Contraindicated in renal impairment, adrenal insufficiency, and hepatic impairment given its antimineralocorticoid activity.

Progestin-only implant

Drug	Dosage	Adverse effects	Drug interactions	Comments
Etonogestrel subdermal implant	Brand: Nexplanon Regimen: 1 implant, replace by 3 years	Irregular bleeding and amenorrhea are the most common effects; also weight gain, acne, headache, breast tenderness, emotional lability, and insertion/removal-site complications.	Same enzyme-inducer interactions as combined pills.	Single rod inserted subdermally in the inner nondominant upper arm by a trained inserter; effective for 3 years. Use backup contraception for 7 days after insertion unless inserted within the first 5 days of the menstrual cycle or immediately postpartum/postabortion. Return to fertility is expected within a couple of weeks of removal.

Progestin-only injectable

Drug	Dosage	Adverse effects	Drug interactions	Comments
Medroxyprogesterone acetate, intramuscular	Brand: Depo-Provera Regimen: 150 mg IM every 12-13 weeks	Irregular bleeding progressing to amenorrhea in most long-term users, weight change, mood change, decreased libido, and reversible bone mineral density loss with long-term use.	Same enzyme-inducer interactions as combined pills reduce effectiveness.	Inject within the first 5 days of menses for immediate effect; if given at any other time, use backup contraception for 7 days. Re-inject no later than 13 weeks after the previous dose. Discuss bone health with long-term (multi-year) use. Delayed return of fertility (up to about a year) after discontinuation should be discussed before starting.
Medroxyprogesterone acetate, subcutaneous	Brand: Depo-SubQ Provera 104 Regimen: 104 mg SC every 12-14 weeks	Same as the intramuscular formulation; injection-site reactions are more prominent with the subcutaneous route.	Same enzyme-inducer interactions as combined pills.	Lower-dose subcutaneous formulation intended for injection into the anterior thigh or abdomen, appropriate for patient or caregiver self-administration where a local training program supports it — an option increasingly recognized in current guidance.

Intrauterine devices — copper (non-hormonal)

No hormonal contraindications apply since there is no systemic hormone exposure; local contraindications are pregnancy, undiagnosed abnormal vaginal bleeding, current pelvic infection or STI, cervical or endometrial malignancy, copper allergy, and an anatomy that prevents correct placement or retention. No Pharmasist Drug Database monograph exists for these devices — they carry Health Canada device licences rather than a drug product monograph.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Copper-T intrauterine device	Brand examples: Flexi-T, Liberte, Mona Lisa, Yanae Duration: Up to 10 years depending on the model	Heavier and/or longer menstrual bleeding, cramping/pain, and (uncommonly) uterine perforation, expulsion, or infection at insertion.	None — no systemic hormone exposure.	Effective immediately, with no backup contraception needed at any point in the cycle. Also effective as emergency contraception when inserted within 7 days of unprotected intercourse. Perforation and expulsion risk is somewhat higher when inserted 4 days to 6 weeks postpartum.
Copper intrauterine ball	Brand: IUB Ballerine Duration: Up to 5 years	Similar to the T-shaped device.	None — no systemic hormone exposure.	Spherical (ball) shape rather than T-shaped, which may reduce the risk of uterine irritation or injury in some patients; a smaller device that may allow easier insertion.

Intrauterine devices — hormonal (levonorgestrel intrauterine system)

Local contraindications: pregnancy, current or recurrent pelvic infection, undiagnosed abnormal vaginal bleeding, uterine or cervical malignancy, cervicitis, acute liver disease, and an anatomy that prevents correct placement. This is not the same product as the levonorgestrel emergency contraceptive pill (Plan B) — do not confuse the two. No Pharmasist Drug Database monograph specific to the intrauterine formulation exists, so these rows are not linked.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Levonorgestrel intrauterine system, 52 mg	Brand: Mirena Duration: Up to 8 years	Spotting for the first 3 to 6 months after insertion; amenorrhea develops in a substantial proportion of long-term users; uncommonly, expulsion or perforation.	None expected — levonorgestrel acts locally at very low systemic exposure; efficacy has not been formally studied with enzyme-inducing medications but is not expected to be clinically reduced given the local mechanism.	Also reduces menstrual blood loss, dysmenorrhea, and endometriosis-related pain. If inserted within 7 days of menses onset, effective immediately; otherwise use backup contraception for 7 days. Approved for up to 8 years of use.
Levonorgestrel intrauterine system, 19.5 mg	Brand: Kyleena Duration: Up to 5 years	Similar to the 52 mg system; prolonged and frequent bleeding/spotting is more common in the first 3 to 6 months, with lower rates of amenorrhea over time than the higher-dose system.	Same as the 52 mg system.	Smaller frame than Mirena; a reasonable option when a smaller device is preferred, including in adolescents and nulliparous patients. If inserted within 7 days of menses onset, effective immediately; otherwise use backup contraception for 7 days.

References

SOGC Clinical Practice Guideline: Canadian Contraception Consensus (Part 1 of 4) — Journal of Obstetrics and Gynaecology Canada, Society of Obstetricians and Gynaecologists of Canada (Black A, Guilbert E, Costescu D, et al.). J Obstet Gynaecol Can 2015;37(10):S1-S28
U.S. Medical Eligibility Criteria for Contraceptive Use, 2024 — MMWR Recommendations and Reports, Centers for Disease Control and Prevention (Nguyen AT, Curtis KM, Tepper NK, et al.). MMWR Recomm Rep 2024;73(RR-4):1-126
No. 329-Canadian Contraception Consensus (Part 4 of 4): Chapter 9 — Combined Hormonal Contraception — Journal of Obstetrics and Gynaecology Canada, Society of Obstetricians and Gynaecologists of Canada (Black A, Guilbert E, Costescu D, et al.). J Obstet Gynaecol Can 2017;39(4):229-268
U.S. Selected Practice Recommendations for Contraceptive Use, 2024 — MMWR Recommendations and Reports, Centers for Disease Control and Prevention (Curtis KM, Nguyen AT, Tepper NK, et al.). MMWR Recomm Rep 2024;73(RR-3):1-77
Canadian Contraception Consensus (Part 3 of 4): Chapter 8 — Progestin-Only Contraception — Journal of Obstetrics and Gynaecology Canada, Society of Obstetricians and Gynaecologists of Canada (Black A, Guilbert E, Costescu D, et al.). J Obstet Gynaecol Can 2016;38(3):279-300
Canadian Contraception Consensus (Part 3 of 4): Chapter 7 — Intrauterine Contraception — Journal of Obstetrics and Gynaecology Canada, Society of Obstetricians and Gynaecologists of Canada (Black A, Guilbert E, Costescu D, et al.). J Obstet Gynaecol Can 2016;38(2):182-222
FSRH Statement: Glucagon-like Peptide-1 (GLP-1) Agonists and Oral Contraception — Faculty of Sexual & Reproductive Healthcare, Clinical Effectiveness Unit. FSRH Statement, February 2025

Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.