Prescription:

Aralen (Chloroquine) is a drug most commonly used to prevent and treat malaria, an infection that is caught from mosquitoes in certain parts of the world. In some cases, it has been used to treat symptoms of rheumatoid arthritis or systemic lupus erythematosus. As well, it has been used to treat some liver diseases caused by protozoa.
Prevention of malaria: For adults, the dose of chloroquine is usually 500 mg once a week, taken on exactly the same day every week. To prevent malaria, start taking the tablets at least 2 weeks before leaving for an area where malaria is a risk and continue taking the tablets for 8 weeks after your return. If it is not possible to start taking the medication 2 weeks ahead of leaving for a malaria risk area, a double dose (2 doses of 500 mg taken 6 hours apart) is recommended for the first dose. Children's doses are based on body weight.
Treatment of malaria: For adults, treatment usually begins with a 1 g (1000 mg) dose followed by 500 mg after 6 to 8 hours. This is followed by a single dose of 500 mg on each of 2 consecutive days. This makes for a 3-day total dose of 2.5 g. Children's doses are based on body weight.