Tobacco Use Disorder: Smoking and Nicotine Cessation

Tobacco use disorder is, for most patients, an addiction to nicotine that behaves as a chronic, relapsing condition — the majority of people who use tobacco need more than one quit attempt before achieving lasting abstinence, and relapse is an expected part of the disease course rather than a treatment failure.^[1] Cigarette smoke delivers nicotine rapidly and repeatedly to nicotinic receptors in the brain's reward pathway; because these receptors desensitize quickly and then re-sensitize within roughly 45 minutes, smoking produces short-lived reward followed by craving and withdrawal, driving the compulsive, repeated dosing pattern at the core of the disorder.

Tobacco use remains the leading cause of preventable death in Canada, and quitting produces measurable benefit at any age — cessation continues to reduce cardiovascular risk even in older adults with decades of smoking history, and quitting earlier in life produces a larger reduction in long-term mortality risk than quitting later. Every patient who uses tobacco should be offered treatment — behavioural counselling combined with pharmacotherapy — since brief advice to quit, on its own, is not an adequate intervention.^[1]

Tobacco use disorder is recognized by the same general behavioural pattern used to diagnose other substance use disorders: impaired control over use (repeated unsuccessful attempts to cut down or stop), continued use despite clear awareness of harm, tolerance, and a characteristic withdrawal syndrome on cessation or significant reduction. In practice, most adults who smoke daily and have already tried and failed to quit unassisted meet this threshold — the practical clinical task is asking every patient about tobacco use and offering treatment to anyone who uses it, not calculating a precise criteria count.^[1]

Nicotine withdrawal syndrome

Withdrawal begins within hours of the last cigarette, is most intense over the first several days, and most acute symptoms resolve over the following weeks, though craving and appetite change can persist longer:

Systemic health consequences of continued tobacco use

These consequences are why treatment matters clinically and why every visit is an opportunity to intervene — they are not, by themselves, part of assessing a single patient's tobacco use disorder.

• Younger age at first cigarette — nicotine dependence can begin with the very first cigarette, with cravings often developing within weeks of starting regular use.
• Family history of tobacco use, or a household member who currently smokes.
• Psychiatric comorbidity — depression, anxiety, PTSD, schizophrenia, and bipolar disorder are all associated with markedly higher smoking rates and lower unassisted quit success.
• Concurrent alcohol or other substance use disorder.
• Peer and social environment where smoking is normalized.
• Occupational or chronic psychosocial stress.
• Concurrent use of other nicotine or tobacco products (vaping, smokeless tobacco, nicotine pouches), which can sustain nicotine dependence even after cigarette use stops.
• Prior unsuccessful quit attempts made without pharmacotherapy or structured counselling support.
• Genetic variation in nicotine-metabolizing enzymes, which affects how quickly nicotine clears and how intense withdrawal feels.

History

• Current tobacco/nicotine use pattern — cigarettes/day, age of first use, and years smoked, plus any concurrent use of vaping products, smokeless tobacco, or nicotine pouches (ask about all of these directly, not just cigarettes).
• Prior quit attempts — number, methods used (pharmacotherapy, counselling, or unassisted), longest period of abstinence achieved, and the specific trigger for each relapse.
• Comorbid psychiatric and substance use history.
• Interacting medications — ask specifically about drugs cleared via CYP1A2 (theophylline, clozapine, olanzapine, some tricyclic antidepressants, warfarin), since quitting itself changes their clearance (see Monitoring & Follow-up).
• Pregnancy status in any patient of childbearing potential.

Motivational assessment

Ask two simple scaled questions to structure a brief motivational conversation: "On a scale of 1 to 10, how important is it for you to quit smoking right now?" and "On a scale of 1 to 10, how confident are you that you could quit?" As long as the patient does not select the lowest possible score, ask why they chose that number rather than a lower one — this elicits the patient's own reasons for change rather than the clinician supplying them.

Grading dependence severity — the Fagerstrom Test for Nicotine Dependence

The Fagerstrom Test is a 6-item, clinician- or self-administered point-sum tool that grades physical nicotine dependence; a shorter time to the first cigarette of the day and a higher number of cigarettes/day both indicate heavier dependence and a greater likelihood that pharmacotherapy will be needed for a successful quit attempt.^[2]

Sum all 6 items for a total score of 0-10: under 5 = low dependence; 5 = moderate dependence; 6-7 = high dependence; 8-10 = very high dependence. A score of 6 or higher is commonly used to prioritize starting pharmacotherapy, though in practice essentially every daily smoker who is willing to quit should be offered it regardless of score.^[2]

Investigations

No laboratory test is required to diagnose or manage tobacco use disorder. Exhaled carbon monoxide or cotinine testing can objectively confirm recent abstinence in a research, occupational, or medico-legal context, but is not needed for routine clinical care. If the patient uses an interacting medication (warfarin, clozapine, theophylline), note the baseline level/INR so a post-quit change can be recognized (see Monitoring & Follow-up) — this is not needed before starting treatment itself.

• Achieve complete, sustained abstinence from all tobacco products — smoke-free, without even a single puff, for a minimum of 6 months.
• For a patient not yet willing to commit to complete cessation: support a meaningful reduction in tobacco use over time, or a switch to a less harmful nicotine source, as a step toward an eventual quit attempt.
• Prevent and minimize nicotine withdrawal symptoms and cravings during a quit attempt.
• Support the patient through relapse without abandoning the overall treatment goal, since most people need more than one attempt.
• Reduce the long-term risk of tobacco-attributable cardiovascular, respiratory, and cancer-related disease.
• Anticipate and counsel on post-cessation weight gain so it does not become a reason to relapse.
• Identify and address use of other nicotine or tobacco products (vaping, smokeless tobacco, nicotine pouches) alongside or instead of cigarettes.

Behavioural counselling — offer to every patient

Offer behavioural counselling to every patient who uses tobacco, regardless of current motivation to quit — it is an evidence-based intervention addressing the behavioural, cognitive, and social drivers of tobacco use, not simply encouragement.^[1] Effective content includes education on the harms of tobacco use and the benefits of quitting, identification of personal triggers, motivational interviewing and cognitive behavioural techniques to address unhelpful beliefs about smoking, and practical coping skills for cravings, high-risk situations, and slips.

Effective delivery formats include face-to-face counselling (individual or group), telephone counselling, text-message support, and web-based programs — but pair an online-only intervention with professional behavioural support rather than using it alone, since accountability and social support are difficult to replicate through a website by itself.^[1] There is a dose-response relationship between counselling contact and quit success: counsel at least once before the quit date, again in the week following it, and weekly thereafter as needed; programs delivered over roughly 8-24 weeks show benefit that persists at 6-month follow-up.

Choosing a quit method

Most cessation guidelines favour abrupt cessation on a set quit date, but a gradual reduction approach achieves comparable quit rates in trials, so either is a reasonable patient-preferred option. Gradual approaches include reducing cigarettes by a set amount from baseline, spacing cigarettes further apart, or delaying the first cigarette of the day — all should still culminate in an actual quit date. Using a short-acting NRT product during the reduction phase, before the quit date, appears to improve success compared with reduction alone.

Post-cessation weight gain

Anticipate and normalize weight gain as a common but manageable part of quitting, since it is a genuine reason patients relapse. Nicotine suppresses appetite and raises metabolic rate, and many patients also use eating to replace the hand-to-mouth ritual or dopamine reward of smoking. Cessation pharmacotherapy (NRT, bupropion, or varenicline) is associated with less weight gain than quitting unaided, and bupropion specifically tends to produce the least weight gain of the three given its appetite-suppressing property. Reassure patients that the health risks of continued smoking far outweigh the risks of modest post-cessation weight gain.

Techniques with insufficient evidence — do not recommend

• Acupuncture — systematic reviews and meta-analyses show mixed, low-certainty results.
• Laser therapy — no reliable supporting evidence.
• Hypnotherapy — insufficient evidence of effectiveness despite anecdotal reports of success.
• Clove cigarettes (kreteks) — still deliver tobacco, nicotine, and similar toxins to conventional cigarettes; not a safer alternative.

Current Canadian guidance advises against relying on acupuncture, laser therapy, or hypnotherapy for smoking cessation, given the insufficient and low-certainty evidence base.^[1]

Financial incentives

Vouchers or monetary payments for verified abstinence can improve quit rates and help sustain abstinence even after the incentive period ends, and can be considered as an adjunct where a structured incentive program is available.

Electronic nicotine delivery systems (e-cigarettes / vaping)

Electronic nicotine delivery systems (ENDS, e-cigarettes, vapes) heat a nicotine-containing liquid to produce an inhaled aerosol, rather than burning tobacco. No ENDS product is currently authorized in Canada specifically for smoking cessation, and current Canadian guidance conditionally recommends against using e-cigarettes as a cessation aid for most patients, reserving them for patients who have been unable to quit using approved first-line pharmacotherapy and behavioural support, or who express a strong, informed preference for this approach after those options have been discussed.^[1]

The evidence is genuinely mixed and still evolving. ENDS deliver far fewer of the harmful combustion products found in cigarette smoke, and switching completely from cigarettes to ENDS reduces exposure to many tobacco-specific carcinogens and cardiovascular toxicants. At the same time, ENDS are not risk-free — they have been linked to acute lung injury (below), their long-term health effects remain unknown, and dual use (continuing to smoke cigarettes while also vaping) provides little to no health benefit over smoking alone. Because of these unresolved questions, frame ENDS as a harm-reduction option for a patient who has genuinely been unable to quit using proven therapies, not as an equivalent first-line alternative to varenicline, bupropion, or NRT.

If a patient chooses to use ENDS as a substitute for cigarettes, the treatment goal remains eventual cessation of ENDS use as well, not indefinite dual maintenance — though structured protocols for vaping cessation specifically are still an active area of investigation, and preliminary evidence suggests varenicline may be useful for that specific purpose.

ENDS use, particularly with tetrahydrocannabinol (THC)-containing products and vitamin E acetate as a diluent, has been linked to a serious inflammatory lung condition — e-cigarette or vaping product use-associated lung injury (EVALI) — presenting with dyspnea, cough, pleuritic chest pain, fever, and gastrointestinal symptoms; this requires urgent medical assessment (see Red Flags & Refer).

In a patient with cardiovascular disease specifically, use particular caution recommending ENDS, since nicotine exposure from any source can raise heart rate, blood pressure, and arterial stiffness and impair the vascular endothelium.^[4]

Smokeless tobacco

Smokeless tobacco (chewing tobacco, dry/moist snuff, snus) is not burned or inhaled but remains addictive through its nicotine content and carries serious health risks of its own, including oral cancer. Counselling is first-line treatment and should be offered the same as for cigarette smoking. NRT can be used to support cessation, though the evidence specifically in smokeless tobacco users is lower-certainty; varenicline is an effective option in this population, while bupropion has not been shown to increase abstinence for smokeless tobacco use specifically.

Pregnancy

Smoking cessation should be encouraged and supported at every stage — preconception, pregnancy, and postpartum — given clear risks to both the pregnant person and the fetus/infant. Behavioural counselling is first-line. If pharmacotherapy is needed, NRT may be used with a risk-benefit discussion, generally preferring the lowest effective dose of a short-acting product (gum) and reserving the patch for heavier dependence, removed at bedtime to reduce fetal nicotine exposure overnight; data for bupropion and varenicline in pregnancy are limited.^[5] This chapter covers pregnancy only briefly — for complete guidance on medication risk-benefit counselling in pregnancy, see the dedicated pregnancy-medication-use resource.

Breastfeeding

Continued breastfeeding is associated with a lower relapse rate after quitting. If pharmacotherapy is needed while breastfeeding, NRT and bupropion may be used weighing benefit against risk; minimize infant nicotine exposure by using NRT immediately after a feed or at least 2 hours before the next one, and consider removing a nicotine patch overnight. There are no published safety data on varenicline during breastfeeding, so it is not recommended in this population until more evidence is available.

Adolescents

Evidence for any specific tobacco cessation strategy in youth is limited, and no single strategy currently has strong evidence supporting widespread use in this age group. Group counselling and other behavioural interventions show the most promise and are first-line. NRT combined with behavioural therapy may be considered for an adolescent unable to quit with behavioural support alone, though evidence for its efficacy and safety at this age remains limited — involve a clinician experienced in adolescent tobacco treatment where possible. Ask specifically about e-cigarette use in this population, since ENDS are now a common route of nicotine initiation in youth, including those who have never smoked a cigarette.

Psychiatric comorbidity

A patient with depression, anxiety, schizophrenia, bipolar disorder, or another psychiatric illness smokes at substantially higher rates and benefits at least as much from cessation treatment as the general population — do not withhold effective pharmacotherapy from this group. The historical concern that varenicline and bupropion cause neuropsychiatric adverse events, which led to Health Canada's original 2009 boxed warning, was substantially revised after the large EAGLES trial found no significant excess of neuropsychiatric adverse events attributable to either drug compared with nicotine patch or placebo, including in patients with stable psychiatric illness; the warning was subsequently downgraded to a standard warning/precaution.^[3] In practice, varenicline and bupropion remain appropriate options for a patient with stable psychiatric illness, provided the patient is monitored — as with any patient starting these agents — for new or worsening mood or behavioural changes, with closer monitoring for anyone with an active or unstable psychiatric condition. Quitting smoking itself can transiently unmask or worsen depressive symptoms in some patients independent of any medication used, so distinguishing a medication effect from a quit-related mood change requires careful clinical assessment rather than automatic drug discontinuation.

Cardiovascular disease

Continuing to smoke is more dangerous than any cessation pharmacotherapy option in a patient with cardiovascular disease. NRT is generally considered safe in stable cardiovascular disease and should be offered before and after discharge for a patient hospitalized with acute coronary syndrome; use caution and closer supervision when initiating within 2 weeks of a myocardial infarction or in a patient with unstable angina or a serious arrhythmia. A nicotine patch may be preferable to short-acting NRT forms in this population given its more consistent, steady nicotine delivery. Varenicline is also a reasonable option following an acute coronary syndrome event to support cessation.^[4]

Older adults

No specific dose adjustment is required for NRT in older adults. Bupropion and nortriptyline may need a lower starting dose given reduced clearance and increased sensitivity to central nervous system effects; obtain a baseline ECG before starting nortriptyline in a patient over 50.

Renal and hepatic impairment

Varenicline requires a reduced maximum dose and slower titration in severe renal impairment and is not recommended in end-stage renal disease; no adjustment is needed for mild-moderate renal impairment or for hepatic impairment. Bupropion requires caution and a reduced dose/frequency in renal impairment, and is not recommended in severe hepatic impairment (or limited to 150 mg every other day if used). No dose adjustment is required for NRT in renal or hepatic impairment.

Prescribe NRT in blocks of 2-4 weeks to allow reassessment of adherence, effectiveness, and tolerability at each renewal.

Schedule follow-up within the first week after the quit date — particularly for a patient using NRT, to check for adequate symptom control and adverse effects — then weekly as needed, monthly for the first 3 months, and at 6 and 12 months; more counselling contact is associated with better outcomes.

Use a more intensive follow-up schedule (weekly initially, then every 2 weeks for the first 3 months, then at 6, 9, 12, 18, and 24 months) for a higher-risk patient: heavy nicotine dependence, multiple prior failed attempts, significant psychosocial stress, comorbid substance use or psychiatric illness, use of an interacting medication, or a medically urgent reason to quit.

Monitor every patient starting varenicline or bupropion for new or worsening mood, behaviour, or suicidal ideation, particularly in the first few weeks and after any dose change.

Reassess for drug interactions after a successful quit: stopping smoking removes CYP1A2 induction, which can raise blood levels of drugs such as theophylline, clozapine, olanzapine, some tricyclic antidepressants, and warfarin — arrange appropriate monitoring (e.g., INR, clozapine level) and anticipate a possible dose reduction in these medications after a quit date, not only at treatment initiation.

Ask about and monitor weight change, and reinforce that pharmacotherapy is associated with less post-cessation weight gain than quitting unaided.

1. Confirm correct technique and adherence first — for NRT, check chewing/parking technique with gum, correct lozenge/spray use, patch rotation, and whether acidic beverages are being taken too close to dosing (this reduces buccal nicotine absorption).
2. If cravings persist on a nicotine patch alone, add a short-acting NRT product (gum, lozenge, inhaler, or mouth spray) as breakthrough medication rather than increasing the patch dose alone.
3. If a full, adherent trial of one first-line monotherapy is inadequate, switch to a different first-line option or move to combination NRT if not already used.
4. If a patient is still smoking 4 weeks after starting varenicline, reassess the overall treatment plan rather than continuing it unchanged.
5. For a heavy or highly dependent smoker with an inadequate response to standard-dose NRT, consider off-label higher-dose NRT (up to 35-40 mg/day using additional patches or an added short-acting product) under health-care provider supervision.
6. If first-line options have genuinely failed, are not tolerated, or are unaffordable, move to a second-line agent (nortriptyline or clonidine).
7. After any relapse: normalize it as an expected part of a chronic relapsing condition, identify the specific trigger or barrier involved, and offer to restart or switch pharmacotherapy and re-engage counselling at the same visit — do not wait for a future visit or for the patient to seem more ready to quit.

• Treating a relapse as a treatment failure rather than an expected part of a chronic, relapsing condition — most people need more than one quit attempt.
• Withholding varenicline or bupropion from a patient with stable psychiatric illness based on the outdated original boxed-warning-era caution — current evidence does not support this restriction, and this population benefits at least as much from cessation.
• Starting bupropion without asking directly about a seizure history or a current/past eating disorder.
• Choosing a starting NRT dose without accounting for baseline cigarette consumption and time-to-first-cigarette.
• Under-dosing NRT out of excess caution, leaving the patient in withdrawal and prompting continued smoking or early relapse.
• Stopping NRT, varenicline, or bupropion after a single slip (one cigarette) rather than continuing the planned course and re-engaging counselling.
• Offering counselling alone or pharmacotherapy alone when combined treatment outperforms either alone.
• Recommending e-cigarettes as a routine, unconditional first-line option — current Canadian guidance conditionally recommends against this except for a patient who has not succeeded with approved therapies.
• Asking only about cigarette smoking and missing concurrent use of vaping products, smokeless tobacco, or nicotine pouches.
• Missing a needed dose adjustment when a patient on an interacting drug (theophylline, clozapine, warfarin) successfully quits smoking, since drug levels can rise once CYP1A2 induction from tobacco smoke resolves.
• Assuming NRT is unsafe in cardiovascular disease — for most patients, continuing to smoke is a greater cardiovascular risk than using NRT.

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.

Nicotine replacement therapy (NRT)

Select the starting dose by baseline cigarette consumption and, for gum/lozenge, by how soon the first cigarette of the day is smoked. Combination therapy (patch plus an as-needed short-acting product) outperforms any single NRT form alone and is a genuine first-line option, not only a fallback for monotherapy failure.

Combination NRT — a patch for steady baseline coverage plus an as-needed short-acting product (gum, lozenge, inhaler, or mouth spray) for breakthrough cravings — should be used at the individual product doses above, selected the same way as when each is used alone. This combination is a genuine first-line strategy, not a step reserved only for monotherapy failure.

Nicotinic receptor partial agonists

Both agents partially activate the same alpha4-beta2 nicotinic receptor targeted by nicotine, reducing craving and withdrawal while blunting the reward of smoking if the patient lapses. Do not combine the two with each other.

Antidepressant

Reduces craving and withdrawal through a non-nicotinic mechanism (weak dopamine/norepinephrine reuptake inhibition). Its defining risk is dose-related seizures.

Second-line / alternative agents

Neither agent has a formal Health Canada indication for smoking cessation. Consider after first-line options have failed, are not tolerated, or are unaffordable.

Other nicotine products

Not a first-choice recommendation, but relevant to ask about since patients increasingly use these products, sometimes instead of or alongside cigarettes.

Investigational / not routinely recommended

Acupuncture, laser therapy, and hypnotherapy each lack sufficient evidence to recommend for smoking cessation. Clove cigarettes (kreteks) still deliver tobacco, nicotine, and similar toxins to conventional cigarettes and are not a safer alternative. No electronic nicotine delivery system (e-cigarette/vape) product is currently authorized in Canada specifically for smoking cessation — see Non-pharmacologic Treatment for the full, balanced discussion of their role as a harm-reduction option.