Hydroxychloroquine and Mefloquine interaction
Hydroxychloroquine and Mefloquine: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Hydroxychloroquine (Plaquenil) label · effective 2026-04-09
Co-administration of PLAQUENIL with other antimalarials known to lower the seizure threshold (e.g., mefloquine) may increase the risk of seizures.
From the Mefloquine (Mefloquine Hydrochloride) label · effective 2025-04-03
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.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.