Mefloquine is recommended for areas where malaria is chloroquine-resistant. Its functioning was still mysterious in 1994, and a wide range of conditions and side-effects (physiological and psychological) are given as pretexts for avoiding or discontinuing it's use. Many malaria-treatment drugs are also contra-indicated when taking Mefloquine. Treatment with increased dosages of Mefloquine is not recommended without close medical supervision. Treating malaria while on Mefloquine is possible with sulfa drugs (e.g. Fansidar), but these may be difficult or impossible to obtain in country. Considering Mefloquine? Consider the following. I am not a physician, parasitologist or pharmacologist. I did, however take mefloquine (brand-name "Lariam") as a malaria prophylaxis, and had to abandon it's use due to side-effects.

an antimalarial drug (trade name Larium and Maphaquine) that is effective in cases that do not respond to chloroquine; said to produce harmful neuropsychiatric effects on some people

A drug used against malaria.