Malaria, Treatment

Malaria is a life-threatening but genuinely curable parasitic infection caused by 5 species of Plasmodium protozoa transmitted through the bite of an infected Anopheles mosquito. This chapter covers treatment of a diagnosed or strongly suspected infection — species identification, uncomplicated-versus-severe classification, first-line regimens, and radical cure of the relapsing species. For pre-travel chemoprophylaxis, bite-avoidance counselling, and standby emergency self-treatment for travellers who have not yet been diagnosed, see the companion Malaria Prevention chapter.

Two decisions drive everything that follows once malaria is confirmed. The first is severity: uncomplicated malaria is treated with a full course of oral therapy, while severe or complicated malaria — regardless of the infecting species — is a medical emergency requiring immediate parenteral therapy, ideally in an intensive care unit.^[1] The second is species: P. falciparum and the zoonotic P. knowlesi can progress to severe, fatal disease within hours to days in a nonimmune patient and are managed with the same urgency, while P. vivax and P. ovale form dormant liver hypnozoites that require a separate course of primaquine — after glucose-6-phosphate dehydrogenase (G6PD) testing — to achieve radical cure and prevent relapse.^[1]

Why recognition still matters once malaria is on the differential

Fever is the cardinal symptom, typically with chills/rigors, headache, myalgia, fatigue, nausea, vomiting, or diarrhea; classic cyclical fever patterns are unreliable and their absence never excludes the diagnosis.^[1] Once malaria is confirmed by blood smear, the clinical question shifts from "could this be malaria" to "how severe is this episode and which species is it" — both of which determine the entire treatment pathway below.

Species identification changes the treatment plan, not just the label

• Infection with P. falciparum or P. knowlesi in a nonimmune host — the 2 species capable of rapid progression to severe, fatal disease.^[1]
• Age under 5 years, and pregnancy — both associated with a disproportionately higher risk of severe disease and death from falciparum malaria.^[1]
• Nonimmune status: travellers, and people who grew up in or were born in an endemic area but have been away from malaria exposure for 6-12 months or more — partial immunity wanes and no longer reliably prevents severe disease.^[1]
• High parasite density (hyperparasitemia) at diagnosis — itself one of the defining criteria for severe malaria, and a risk factor for post-artesunate delayed hemolysis after treatment (see Monitoring & Follow-up).^[2]
• Delayed treatment initiation, or delayed recognition that a patient's oral therapy is not being tolerated — inability to tolerate oral medication is itself a risk factor for progression to severe disease.^[1]
• Infection acquired in, or travel through, an area with known chloroquine-resistant P. vivax (notably New Guinea/Papua) — standard chloroquine-class treatment can fail outright in these regions.^[1]
• Unknown or untested G6PD status in a patient who will need primaquine for radical cure — a real barrier to completing treatment safely, not just a documentation gap.
• HIV infection, other immunocompromising conditions, or asplenia — plausible contributors to a more severe course; maintain a lower threshold for hospitalization and parenteral therapy in these patients.

Three questions before choosing a regimen

CATMAT frames malaria management around 3 questions, and every treatment decision in this chapter follows from the answers: is this infection caused by P. falciparum (or P. knowlesi, managed the same way)? Is this a severe or complicated infection? Was it acquired in an area of known drug resistance? When in doubt about resistance, treat all P. falciparum as drug-resistant — true for the great majority of cases seen in Canada.^[1]

Confirm species and quantify parasitemia

Thick and thin blood smear microscopy remains the reference standard: the thick smear is more sensitive for detecting parasites, and the thin smear allows species identification and quantification of parasite density (percent parasitemia) — a number that is not just descriptive, since it directly determines whether the episode meets criteria for severe malaria.^[1] A rapid diagnostic test can support same-day triage but does not replace microscopy for species confirmation and parasite density. P. malariae, P. knowlesi, and P. falciparum can be difficult to distinguish on a blood smear; PCR testing or review by an experienced pathologist/reference laboratory should be pursued for species confirmation when this matters clinically, and any mixed infection or infection of unknown species should be managed as P. falciparum.^[4]

Table 7.1 — criteria for severe (complicated) falciparum malaria

In a patient with P. falciparum parasitemia and no other obvious cause of symptoms, any 1 of the following clinical or laboratory features classifies the episode as severe malaria:^[1]

Nonimmune individuals include anyone born or raised in a non-endemic setting, and anyone who has been away from an endemic setting for 6-12 months or more even if they grew up there; semi-immune individuals have long-term residence in an endemic country plus a history of prior malaria episodes.^[1] Patients unable to tolerate oral medication are, separately, at risk of progressing to severe disease and should be treated as such regardless of whether they meet a Table 7.1 criterion.^[1]

Ongoing assessment through treatment

Assess every patient clinically each day until fever resolves and at any time symptoms recur; for P. falciparum and P. knowlesi, repeat blood smears daily until they are negative, ideally documenting a negative smear within 1 week of completing treatment.^[1] Obtain blood cultures on every malaria patient to exclude a co-existing bacterial infection, particularly if there is any evidence of shock.^[1]

• Cure the infection and, for uncomplicated P. falciparum/P. knowlesi, prevent progression to severe disease.^[1]
• For severe malaria, the primary objective is preventing death; for cerebral malaria specifically, preventing permanent neurologic deficit is also a primary objective.^[1]
• For malaria in pregnancy, the primary objective is saving the life of the mother.^[1]
• Achieve radical cure of P. vivax and P. ovale — clearing both the acute blood-stage infection and the dormant liver hypnozoites responsible for relapse.
• Access parenteral therapy (IV artesunate, or IV quinine as the alternative) as quickly as possible for any patient meeting severe-malaria criteria or unable to tolerate oral therapy.
• Complete a full, correctly sequenced course of follow-on oral therapy after any period of IV artesunate — treatment is not finished when parenteral therapy stops.^[1]
• Minimize adverse effects and the risk of recrudescence as secondary objectives once the primary objective above is being met.^[1]

Uncomplicated P. falciparum or P. knowlesi

Treat infection possibly or definitely acquired in a drug-resistant region — the great majority of P. falciparum malaria seen in Canada — with 1 of the following:^[1]

Artemether-lumefantrine (Coartem®), the World Health Organization's global first-line oral combination therapy, remains not licensed or commercially available in Canada as of this chapter's authoring — the same limitation described in the companion Prevention chapter's standby-treatment section.^[1] A patient who arrives already taking artemether-lumefantrine obtained abroad can generally continue and complete it under specialist guidance rather than switching once a course is tolerated and underway, but confirm it was purchased from a jurisdiction with reliable pharmaceutical regulation, given the real risk of counterfeit antimalarials in some endemic regions.^[1]

Hospitalize or observe every case

Consider hospital admission for every nonimmune patient and every child with P. falciparum or P. knowlesi malaria, severe or uncomplicated, to confirm the antimalarial is tolerated and to detect complications or early treatment failure. If admission is not pursued, observe the patient through the first dose in the emergency department, and either provide the remaining doses before discharge or direct the patient to a pharmacy that can fill the full course immediately — do not send a newly diagnosed patient home with only a prescription and an unfilled course.^[1]

Accessing parenteral therapy: the Canadian Malaria Network

The Canadian Malaria Network (CMN) keeps supplies of IV artesunate and IV quinine at designated centres across the country and can be reached 24 hours a day to arrange rapid access and case-management support for any suspected or confirmed severe malaria case — call before treatment is needed, not after.^[3] Appendix 5's own published guidance still directs that, for patients who do not meet severe-malaria criteria but need parenteral therapy purely because they cannot tolerate oral treatment, IV quinine should be used and artesunate reserved for those with severe malaria, on the basis that artesunate supply was limited; that specific supply rationale predates artesunate's August 2025 commercial licensure, so confirm current local stock and CMN guidance rather than assuming the older scarcity-driven triage still applies exactly as written — either way, the CMN remains the correct first call.^[3] If a severe or complicated case is diagnosed and the parenteral drug will not be available within about an hour, start oral quinine (after an antiemetic, or by nasogastric tube if necessary) as a bridge until parenteral therapy arrives — but do not use a quinine loading dose if the patient received quinine or quinidine within the preceding 24 hours, or mefloquine within the preceding 2 weeks.^[1]

IV artesunate regimen

Give artesunate 2.4 mg/kg by slow IV bolus injection over 1-2 minutes at 0, 12, and 24 hours.^[2] Reassess clinical status and parasitemia after the initial 3 doses (thin smear collected at least 4 hours after the last dose); if parasitemia remains elevated or oral medication still cannot be tolerated, continue artesunate 2.4 mg/kg once every 24 hours (starting at the 48-hour mark) for up to a total of 7 days.^[2][1] Stop IV artesunate as soon as the patient can reliably tolerate oral medication; for patients who do meet severe-malaria criteria, give at least 24 hours of parenteral therapy before transitioning, even if oral tolerance returns sooner.^[1] No dose adjustment is required for renal or hepatic impairment or for older age; pediatric dosing (age 6 months and older) uses the same 2.4 mg/kg regardless of weight — simpler than, and superseding, the older World Health Organization-derived recommendation of 3 mg/kg specifically for children under 20 kg still referenced in CATMAT's 2019 text, and the dosing now reflected in the current Health Canada-approved product label.^[2]

Follow-on oral therapy after IV artesunate — always required, and the exact combination depends on how many doses were given

IV artesunate alone is never definitive treatment: every patient who receives it needs a complete course of oral follow-on therapy, started roughly 4 hours after the final artesunate dose.^[1] The specific follow-on regimen depends on artesunate exposure:^[1]

Whichever option is chosen, do not select a drug the patient already took as chemoprophylaxis for this trip, and do not use atovaquone-proguanil if creatinine clearance is under 30 mL/min.^[1] If the original infection was P. vivax or P. ovale, this follow-on course still needs to be paired with a separate primaquine radical-cure course — artesunate itself does not touch the dormant liver hypnozoites of either species.^[2]

IV quinine regimen (when artesunate is contraindicated or unavailable)

Quinine dihydrochloride: loading dose 5.8 mg/kg base (7 mg/kg salt) by IV infusion pump over 30 minutes, immediately followed by a maintenance dose of 8.3 mg/kg base (10 mg/kg salt) diluted in 10 mL/kg isotonic fluid by IV infusion over 4 hours. Repeat the maintenance dose every 8 hours until the patient can swallow (at least 24 hours if treating severe malaria), then switch to oral quinine sulfate (plus doxycycline or clindamycin) to complete 7 days total, or to a full course of oral atovaquone-proguanil.^[1] Do not give the loading dose if the patient received quinine or quinidine in the preceding 24 hours, or mefloquine in the preceding 2 weeks; if more than 48 hours of parenteral quinine is required, reduce the maintenance dose by one-third to one-half, and consider QTc monitoring when a loading dose is used.^[1]

Uncomplicated P. vivax, P. ovale, and P. malariae — acute blood-stage treatment

Chloroquine was historically the treatment of choice for non-falciparum malaria outside New Guinea (Papua New Guinea and Indonesian Papua), but chloroquine has not been commercially available in Canada since 2023 — the same currency point established in the companion Prevention chapter. Hydroxychloroquine is the practical Canadian substitute, dosed at standard treatment strength: 800 mg salt (620 mg base) as an initial dose, then 400 mg salt (310 mg base) at 6, 24, and 48 hours (total 2,000 mg salt/1,550 mg base) — see Drug Tables for pediatric weight-based dosing.^[7]

P. malariae is reliably cured by the same standard hydroxychloroquine treatment course; it is not typically life-threatening, but chronic untreated infection has been associated with splenomegaly, hypersplenism, or renal dysfunction, so treatment should not be deferred simply because the patient looks well.^[1]

This 30 mg base daily dose is CATMAT's standard recommendation regardless of where the infection was acquired, reflecting a 2019 update from the older, lower dose once used outside Southeast Asia/Oceania — decreased primaquine responsiveness is well documented in P. vivax acquired in that region, and using the higher dose everywhere avoids inadvertent under-dosing.^[1]

• Hospitalize (or, at minimum, closely observe) every patient with confirmed or strongly suspected P. falciparum or P. knowlesi malaria, and manage severe malaria in an ICU whenever possible.^[1]
• Monitor vital signs, level of consciousness, respiratory rate/pattern, and urine output as frequently as the clinical situation demands in severe malaria.^[1]
• Check blood glucose by rapid stick test at least every 4 hours in severe malaria, more often in an unconscious patient — quinine itself can precipitate hypoglycemia by stimulating insulin release, and hypoglycemia can otherwise be silent in a critically ill patient.^[1]
• Treat seizures promptly if they occur; there is no role for prophylactic anticonvulsant medication.^[1]
• Avoid corticosteroids for cerebral or severe malaria — associated with worse outcomes in trial data.^[1]
• Individualize fluid resuscitation to estimated deficit; avoid unnecessarily aggressive fluid boluses, since trial evidence in children with severe febrile illness (including malaria) has suggested possible harm from liberal fluid resuscitation rather than benefit.^[1]
• Correct bleeding/coagulopathy with blood products and vitamin K as needed, and obtain blood cultures on every malaria patient to exclude concurrent bacteremia — empirically cover with broad-spectrum antibiotics if there is any evidence of shock.^[1]
• Exchange transfusion is no longer recommended. Older Canadian guidance (2019) described exchange transfusion as a possible adjunct for hyperparasitemic falciparum malaria; current evidence, reflected in the CDC's 2026 severe-malaria guidance and the World Health Organization's 30 November 2024 malaria guidelines, does not support it — a comparative study found no survival benefit despite faster parasite clearance, and IV artesunate itself now reduces parasite burden quickly enough that exchange transfusion adds risk without demonstrated benefit. Treat this as superseding the older exchange-transfusion recommendation.^[8][9]
• Report every confirmed case to the relevant provincial or territorial public health authority — malaria is a reportable disease in Canada, the same requirement described in the companion Prevention chapter.

Pediatrics

Dose every oral regimen by current body weight, and never exceed the adult dose.^[4] Atovaquone-proguanil and artemether-lumefantrine (where used outside Canada) are only used in children weighing 5 kg or more.^[4] Quinine-based regimens can be logistically difficult in young children given limited non-capsule formulations; when a quinine regimen is used in a child under 8 years old, pair it with clindamycin rather than doxycycline, and do not use tetracycline in this age group.^[4] IV artesunate is approved from age 6 months at the same 2.4 mg/kg dose used in adults, with no weight-based tiering; there is insufficient clinical data below 6 months of age, and pharmacokinetic modelling suggests higher drug exposure in that age group, so use only after specialist consultation when the benefit of treating severe malaria clearly outweighs the uncertainty.^[2] Primaquine radical cure and its G6PD-testing requirement apply at any pediatric age, dosed 0.5 mg base/kg once daily for 14 days (maximum 30 mg/day).^[1]

Pregnancy and breastfeeding

See Choose Initial Treatment for the full trimester-specific regimen selection. In breastfeeding: dihydroartemisinin, an artesunate metabolite, is present in breast milk, and the benefit of breastfeeding should be weighed against this exposure on an individual basis rather than withholding artesunate from a mother who needs it for severe malaria.^[2] Hydroxychloroquine is compatible with breastfeeding. Primaquine is contraindicated during breastfeeding unless both the breastfeeding parent and the infant have documented normal G6PD activity, since the drug can transfer through breast milk.^[1]

G6PD deficiency

Test G6PD activity before giving primaquine for any indication — never assume normal activity, and never give primaquine empirically while awaiting a result.^[1] Because G6PD deficiency is X-linked, a female patient can be heterozygous with intermediate enzyme activity that a qualitative screen alone may not reliably classify — pursue quantitative testing when a qualitative result is borderline, or when there is any uncertainty, before making a final decision.^[1] The World Health Organization's 30 November 2024 malaria guidelines newly endorse point-of-care qualitative and semiquantitative G6PD tests, not only laboratory-based quantitative testing, to help guide this decision as rapid testing becomes more widely available — confirm which method your local laboratory or point-of-care program actually uses before relying on a result.^[9] Do not give primaquine to any patient with confirmed or unresolved G6PD deficiency — treat the acute infection with blood-stage therapy alone, counsel on relapse symptoms, and arrange specialist follow-up. Tafenoquine, a single-dose alternative to 14-day primaquine used in the United States and Australia, carries the same G6PD hemolysis risk (and, given its long half-life, requires quantitative rather than qualitative G6PD testing specifically) but is not licensed or marketed in Canada.^[7]

Renal and hepatic impairment

Atovaquone-proguanil is contraindicated in severe renal impairment (creatinine clearance under 30 mL/min) — select an alternative regimen. No dose adjustment is required for IV artesunate in renal or hepatic impairment.^[2] Reduce the parenteral quinine maintenance dose by one-third to one-half if more than 48 hours of therapy is required, reflecting reduced clearance with prolonged use rather than baseline organ impairment specifically.^[1]

Older adults

No IV artesunate dose adjustment is required based on age alone, though clinical data in patients 65 years and older remain limited — apply the usual heightened vigilance for comorbidity and polypharmacy interactions rather than a different dose.^[2]

HIV, other immunocompromise, and asplenia

These patients are plausibly at risk of a more severe clinical course; maintain a lower threshold for hospitalization, closer monitoring, and earlier consideration of parenteral therapy, even when formal Table 7.1 criteria are not yet met.

Assess every hospitalized patient clinically each day, with repeat thick and thin blood smears daily for P. falciparum/P. knowlesi until negative results are documented, ideally within 1 week of completing treatment; for non-falciparum species, assess daily until fever resolves and at any time symptoms recur.^[1] Monitor blood glucose by rapid stick test at least every 4 hours during severe malaria treatment, more often if the patient is unconscious — quinine itself can precipitate hypoglycemia.^[1]

For P. vivax specifically, track the timing of any recurrent parasitemia — under 30 days suggests chloroquine/hydroxychloroquine-resistant P. vivax, and over 30 days suggests primaquine-resistant P. vivax — since the distinction changes what happens next (see Treatment Failure & Next Steps).^[1] Report every confirmed case to the relevant provincial or territorial public health authority. If artesunate or quinine was accessed through the Canadian Malaria Network, complete the attending physician's Form A (at the time of access to/request for the drug) and Form B (at discharge or end of malaria therapy), and notify the supplying organization of any drug-related adverse event — this surveillance data is what keeps these strategically distributed drugs available across the country.^[3]

1. Clinical deterioration or rising parasitemia during oral treatment: this itself meets the "unable to tolerate/progressing" threshold — escalate immediately to parenteral therapy through the Canadian Malaria Network rather than waiting for a formal severe-malaria criterion to appear.
2. Recurrent parasitemia after apparent P. falciparum/P. knowlesi cure: distinguish recrudescence (inadequate initial regimen or resistance) from a new infection; involve infectious disease/tropical medicine, since the original regimen may need reconsideration rather than simple repetition.
3. Recurrent parasitemia after P. vivax treatment: within 30 days of completing treatment, suspect chloroquine/hydroxychloroquine-resistant P. vivax and treat with atovaquone-proguanil plus primaquine (or a 7-day quinine course) instead of repeating hydroxychloroquine alone; after 30 days, suspect primaquine-resistant P. vivax (a radical-cure failure) and seek expert guidance on a repeat or alternative anti-relapse strategy.^[1]
4. A falling hemoglobin identified on the Day 7/14/21/28 post-artesunate monitoring schedule: obtain reticulocyte count, haptoglobin, lactate dehydrogenase, and a direct antiglobulin test; involve hematology, and arrange transfusion if clinically indicated — most cases are self-limited, but some genuinely require it.^[2]
5. G6PD status remains unknown and the patient needs radical cure: do not give primaquine empirically. Arrange testing urgently, and counsel the patient on relapse symptoms to watch for in the meantime.
6. Any diagnostic uncertainty, or difficulty accessing parenteral therapy: escalate directly to the Canadian Malaria Network and/or an infectious disease/tropical medicine specialist rather than troubleshooting alone.^[3]

• Treating a P. falciparum diagnosis as low-urgency because parasitemia looks low or the patient looks well at diagnosis — hospitalize/observe regardless, since falciparum can progress to severe disease within hours.^[1]
• Using chloroquine, which has not been commercially available in Canada since 2023 — use hydroxychloroquine at standard treatment dose instead.
• Completing acute blood-stage treatment for P. vivax/P. ovale without addressing radical cure — without primaquine, relapse from dormant hypnozoites remains likely.
• Giving primaquine without documented G6PD testing, or giving primaquine in pregnancy.^[1]
• Confusing the Canadian primaquine tablet strength (26.3 mg salt/15 mg base) with the required 30 mg base daily treatment dose — a genuinely recurring dispensing error; the correct adult dose is 2 tablets daily, not 1.^[1]
• Selecting a follow-on or non-severe treatment drug that the patient already used as chemoprophylaxis for the same trip.^[1]
• Using atovaquone-proguanil when creatinine clearance is under 30 mL/min.
• Using doxycycline or tetracycline in a pregnant patient — use clindamycin as the quinine partner drug instead.^[1]
• Assuming post-IV-artesunate care ends at discharge because the patient looks well — post-artesunate delayed hemolysis is, by definition, delayed, and the Day 7/14/21/28 hemoglobin monitoring schedule needs to be completed regardless of how the patient looks.^[2]
• Using corticosteroids or prophylactic anticonvulsants for cerebral/severe malaria — neither is supported by evidence, and steroids are associated with worse outcomes.^[1]
• Continuing to rely on exchange transfusion as a routine adjunct for hyperparasitemic falciparum malaria — current evidence does not support it.^[8]
• Delaying treatment while awaiting confirmatory laboratory results when severe malaria is strongly suspected clinically and a smear will be delayed more than about 2 hours — start empiric therapy for presumed P. falciparum.^[1]
• Not calling the Canadian Malaria Network early enough — it exists specifically to prevent delays in accessing parenteral therapy, not only to be contacted after a problem develops.^[3]

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.

Antifolate / Naphthoquinone Combination — First-Line Oral Treatment

First-line for uncomplicated P. falciparum/P. knowlesi and for IV-artesunate follow-on. Do not use if taken as chemoprophylaxis this trip, or if creatinine clearance is under 30 mL/min.

Cinchona Alkaloid — Oral and Parenteral Quinine

Always combined with doxycycline or clindamycin for treatment (never used alone). Do not use a loading dose after recent quinine/quinidine (24 hours) or mefloquine (2 weeks).

Quinine Partner Drugs

Given with quinine for falciparum/knowlesi treatment, and as IV-artesunate follow-on therapy.

Artemisinin Derivative — Severe Malaria (Parenteral)

Health Canada-approved (2025) via Phebra Canada Inc.; not stocked in a retail pharmacy — accessed through the Canadian Malaria Network. No dose adjustment for renal/hepatic impairment or older age.

4-Aminoquinoline Substitute — Non-Falciparum Acute Treatment

Practical Canadian substitute for chloroquine, which has not been commercially available in Canada since 2023. Not sufficient alone for P. vivax/P. ovale — pair with primaquine radical cure (below) after G6PD testing.

8-Aminoquinolines — Radical Cure of P. vivax/P. ovale

Clears dormant liver hypnozoites that no blood-stage-only regimen affects. Mandatory G6PD testing before any use; contraindicated in pregnancy.

Reserve or Not Recommended for Malaria Treatment

Listed because these agents are sometimes reached for by analogy to prevention/prophylaxis use — in treatment specifically, current guidance does not support them as first- or second-line options.