Mefloquine and Quinine interaction
Mefloquine and Quinine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Quinine (QUININE SULFATE) label · effective 2025-10-31
Known hypersensitivity to quinine, mefloquine, or quinidine ( 4 )
…Thrombocytopenia • Idiopathic thrombocytopenia purpura (ITP) and Thrombotic thrombocytopenic purpura (TTP) • Hemolytic uremic syndrome (HUS) • Blackwater fever (acute intravascular hemolysis, hemoglobinuria, and hemoglobinemia) • Known hypersensitivity to mefloquine or quinidine: cross-sensitivity to quinine has been documented [see WARNINGS AND PRECAUTIONS ( 5.6 )].
Concomitant administration of quinine sulfate with the antimalarial drugs, mefloquine or halofantrine, may result in electrocardiographic abnormalities, including QT prolongation, and increase the risk for torsades de pointes or other serious ventricular arrhythmias.
Concurrent use of quinine sulfate and mefloquine may also increase the risk of seizures [see DRUG INTERACTIONS ( 7.2 )] .
Mefloquine In 7 healthy subjects who received mefloquine (750 mg) at 24 hours before an oral 600 mg dose of quinine sulfate, the AUC of mefloquine was increased by 22% compared to mefloquine alone.
From the Mefloquine (Mefloquine Hydrochloride) label · effective 2025-04-03
CONTRAINDICATIONS Use of mefloquine hydrochloride tablets is contraindicated in patients with a known hypersensitivity to mefloquine or related compounds (e.g., quinine and quinidine) or to any of the excipients contained in the formulation.
Concomitant administration of mefloquine and quinine or chloroquine may increase the risk of convulsions.
Other Antimalarial Drugs Concomitant administration of mefloquine and other related antimalarial compounds (e.g., quinine, quinidine and chloroquine) may produce electrocardiographic abnormalities and increase the risk of convulsions (see WARNINGS ).
Other Drugs that Prolong the QTc Interval Coadministration of other drugs known to alter cardiac conduction (e.g., anti-arrhythmic or beta-adrenergic blocking agents, calcium channel blockers, antihistamines or H 1 -blocking agents, tricyclic antidepressants and phenothiazines) might also contribute to a prolongation of the QTc interval.
Concomitant administration of mefloquine and quinine or quinidine may produce electrocardiographic abnormalities.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.