Chloroquine (brand names include: Aralen, Avloclor, Cadiquin, Chlorquin, Delagil, Emquin, Lagaquin, Malaquin, Malarex, Malarivon, Nivaquine, Resochin) is a drug of the aminoquinoline class. Chloroquine is best known as a drug effective for the prevention as well as treatment of malaria. It is also used for the treatment of extraintestinal amebiasis. Chloroquine is an anti-malaria medicine that works by interfering with the growth of parasites in the red blood cells of the human body. Parasites that cause malaria typically enter the body through the bite of a mosquito. Malaria is common in areas such as Africa, South America, and Southern Asia. Chloroquine is used to treat and to prevent malaria. Chloroquine is also used to treat amebiasis (infection caused by amoebae). Chloroquine may also be used for purposes not listed in this medication guide. To prevent malaria: Start taking the medicine 2 weeks before entering an area where malaria is common. Chloroquine is usually taken once per week on the same day each week. Continue taking the medicine regularly during your stay and for at least 8 weeks after you leave the area. If you stop using chloroquine early for any reason, talk to your doctor about other forms of malaria prevention. To treat malaria: Chloroquine is usually given for 3 days, starting with one high dose followed by a smaller dose during the next 2 days in a row. To treat amebiasis: Chloroquine is given in a high starting dose for 2 days followed by a smaller dose for 2 to 3 weeks. You may be given other medications to help prevent further infection.