Adverse effects are similar in frequency and severity to those reported with weekly chloroquine use. The most frequent minor side effects reported by mefloquine users are nausea, strange dreams, dizziness, mood changes, insomnia, headache, and diarrhea. In the last decade in vitro or in vivo resistance has been reported sporadically from malaria-endemic areas. Mefloquine may still be used for chemosuppression in other areas of Southeast Asia. However, at present these concerns remain theoretic and the concurrent use of these agents is not contraindicated.
Insufficient mefloquine is excreted in breast milk to protect a nursing infant.
Although the package insert recommends that mefloquine not be given to children weighing P. falciparum malaria. There are no pharmacokinetic data upon which to recommend a correct dose for children weighing 5 kg. Mefloquine is taken once weekly , beginning 1 week prior to entering a malaria zone, continuing during the period of exposure, and for 4 weeks after leaving the malarial area. For travellers who will be at immediate high risk of drug-resistant falciparum malaria, consideration may be given to the use of a loading dose of mefloquine. The loading dose strategy permits an assessment of drug tolerance before travel and allows a change to a suitable alternative if required.