Mefloquine is not recommended for severe malaria infections, particularly infections from "P. falciparum", which should be treated with intravenous antimalarials. Mefloquine does not eliminate parasites in the liver phase of the disease, and people with "P. vivax" malaria should be treated with a second drug that is effective for the liver phase, such as primaquine. Mefloquine is widely used for the treatment of malaria in pregnancy. Limited data suggests that it is safe for this purpose. Resistance to mefloquine is now common around the west border in Cambodia and other parts of Southeast Asia. The mechanism of resistance is by increase
Mefloquine with an increased risk of birth defects or miscarriages. The drug may be used during breastfeeding, though it appears in breast milk in low concentrations. The World Health Organization gives approval for the use of mefloquine in the second and third trimesters of pregnancy and use in the first trimester does not mandate termination of pregnancy. Mefloquine is metabolized primarily through the liver. Its elimination in persons with impaired liver function may be prolonged, resulting in higher plasma levels and an increased risk of adverse reactions. The mean elimination plasma half-life of mefloquine is between two and four weeks. Total