Which malaria prevention tablets can I give a traveller who is taking warfarin?

A. Travellers on anticoagulants should ensure their clotting time is stable prior to departure. It should be noted that patients on warfarin may have underlying cardiac disease and may be on cardiac medication. Interactions with other medication together with the individual’s medical history should be taken into account when deciding on appropriate malaria prevention tablets. Documented interactions between warfarin and antimalarial tablets Chloroquine There is no interaction between warfarin and chloroquine documented in the BNF, although there is a caution in the Summary of Product Characteristics for Nivaquine. Proguanil There has been an isolated report of an enhanced effect of warfarin when taken together with proguanil [1]. Mefloquine Mefloquine is not considered to be a problem for those taking warfarin. The manufacturer states that ‘although no drug interaction is known with anticoagulants, effects of mefloquine on travellers should be checked before departure.’ Please see ...  more