Quinine
Antimalarials
Antimalarials
Cinchona alkaloid for malaria when ACTs cannot be used, mainly with clindamycin in early pregnancy; causes cinchonism and hypoglycaemia.
Quick facts
- Group
- Antimalarials
- Target
- Heme detoxification in the parasite's digestive vacuole (presumed, like chloroquine)
- Used for
- Uncomplicated P · Severe malaria · Babesiosis
- Key effects
- Cinchonism · Vomiting · Restlessness and confusion
- Monitor
- Blood glucose regularly · ECG · Hearing and vision
- ATC
- P01BC01
No doses: the clinician sets them by the current guideline.
Mechanism of action
An alkaloid from the bark of the South American cinchona tree, the L-isomer of quinidine. Its mechanism is not fully clear but is thought to resemble chloroquine's: it blocks the parasite's detoxification of heme in the food vacuole. It kills mature blood stages (large rings and trophozoites) and the gametocytes of P. vivax, P. ovale and P. malariae, but not P. falciparum gametocytes. It acts more slowly than artesunate and is combined with doxycycline or clindamycin.
- Enters the parasitised red cell
- Blocks heme detoxification in the food vacuole
- Mature blood-stage parasites die
- Paired with clindamycin or doxycycline to finish the cure
Indications
- Uncomplicated P. falciparum malaria in the first trimester of pregnancy, with clindamycin (Colombia's guideline) Malaria →
- Alternative oral treatment when an effective ACT is not available, combined with doxycycline or clindamycin Malaria →
- Severe malaria or pre-referral IM treatment only when artesunate is not available Malaria →
- Babesiosis (occasional use, with other drugs) Babesiosis →
Adverse effects
Common
- Cinchonism: ringing in the ears, reduced high-tone hearing, headache, nausea, dizziness, blurred vision
- Vomiting, abdominal pain and diarrhoea
- Restlessness and confusion
- Pain at IM injection sites; vein irritation with IV infusion
Contraindications
- Hypersensitivity to quinine or quinidine
- Not for night-time leg cramps (serious bleeding, kidney damage and arrhythmias outweigh any benefit)
- Caution: QT prolongation or heart disease, G6PD deficiency, myasthenia gravis, optic neuritis, tinnitus, kidney or liver disease
Key interactions
- Rifampicin and nevirapine
- Lower quinine levels; with rifampicin, recrudescence was markedly more frequent
- Cimetidine and ketoconazole
- Raise quinine levels
- Digoxin
- Quinine raises digoxin levels
- Mefloquine, amiodarone, flecainide and other QT-prolonging drugs
- Additive QT and arrhythmia risk; quinine soon after mefloquine is hazardous
- Neuromuscular blockers
- Effect enhanced
What is monitored
- Blood glucose regularly, more often in pregnancy, children and unconscious patients
- ECG (QT) and blood pressure during IV use
- Hearing and vision (cinchonism)
- Kidney and liver function, platelet count and signs of bleeding
Administration and safety
- IV quinine is given only as a slow, controlled infusion, never as a bolus.
- IM injections can cause pain, sterile abscess and necrosis; never given subcutaneously.
- Oral capsules are swallowed whole with food; the full course is completed with the partner antibiotic.
- Look-alike name: quinidine, a more cardiotoxic isomer; confirm the drug.
Pregnancy and breastfeeding
No evidence that it causes miscarriage or malformations at treatment doses; it is the option for the first trimester in Colombia's guideline, with close glucose monitoring.
Nursing care
- Check glucose before and during treatment; in unconscious patients hypoglycaemia may show only as worsening coma or convulsions.
- Monitor heart rate, blood pressure and ECG during infusion.
- Ask about ringing in the ears, hearing loss and blurred vision; report visual loss at once.
- Teaching: finish the 7-day course with the partner drug; report bleeding, bruising, dark urine or palpitations.
Pharmacokinetics
- Absorption
- Rapid after oral, IM or IV dosing
- Distribution
- Wide, including cerebrospinal fluid, breast milk and placenta; protein binding rises during malaria
- Metabolism
- Extensive in the liver, mainly CYP3A4; it is also a CYP2D6 inhibitor
- Elimination
- Up to a fifth unchanged in urine; accumulates in severe illness and kidney or liver failure
- Half-life
- Variable; longer in severe malaria and in older people
Test yourself
Think of the answer, then tap the question to see it.
What is cinchonism?
The typical cluster of quinine effects: ringing in the ears, reduced hearing, headache, nausea, dizziness and visual disturbance.
Which metabolic adverse effect of quinine is most dangerous, and in whom?
Hyperinsulinaemic hypoglycaemia, especially in pregnant women, young children and the elderly; glucose is checked regularly.
When does Colombia's guideline prefer quinine?
Uncomplicated P. falciparum malaria in the first trimester of pregnancy, combined with clindamycin for 7 days.
Why is quinine not used for night-time leg cramps?
It has not been shown to work and can cause severe bleeding, kidney damage, arrhythmias and allergic reactions.
Connections
← Back to the class: Antimalarials
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Quinine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); Adopción Parcial de Guía de Práctica Clínica Diagnóstico y tratamiento de la malaria, OMS 2022. Guía para Colombia, GPC #67-2022 (Ministerio de Salud y Protección Social (Colombia), 2022); Treatment of Uncomplicated Malaria (Centers for Disease Control and Prevention (CDC), 2026).
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Representative model, for educational purposes only.