The primary anti-malaria drugs for U.S. travelers:
-Lariam, also called mefloquine, is the most prescribed, taken by 25 million people during 17 years of sales. One tablet a week is required, starting one to three weeks before the trip, and continuing for four weeks after returning home.
It costs $7 to $11 a pill.
Serious side effects are rare but include psychiatric symptoms ranging from anxiety and dreams to depression and hallucinations. People with depression, a history of psychiatric disorders or seizures aren't supposed to take it.
During pregnancy, it's OK to use starting in the fifth month.
It's not recommended in parts of Thailand, Cambodia and Myanmar.
-Malarone, available since 2000, is a daily pill begun a day or two before the trip and continuing for one week after returning home.
It costs $4 to $5 a pill.
Side effects generally are mild, such as nausea or headache.
It's not for people with serious kidney damage or for pregnant women.
-Doxycycline is a daily pill begun a day or two before the trip, and continuing for a month after returning home.
Generic versions cost 40 cents a pill.
Side effects include stomach upset and heartburn - users should take it with meals and not before bed - as well as sun sensitivity and, for women, increased risk of yeast infections.
It's not for pregnant women or young children.