Chloroquine is a medication used to prevent and to treat malaria in areas where malaria is known to be sensitive to its effects. Certain types of malaria, resistant strains, and complicated cases typically require different or additional medication. It is also occasionally used for amebiasis that is occurring outside of the intestines, rheumatoid arthritis, and lupus erythematosus. It is taken by mouth. Common side effects include muscle problems, loss of appetite, diarrhea, and skin rash. Serious side effects include problems with vision, muscle damage, seizures, and low blood cell levels. It appears to be safe for use during pregnancy but has not been well studied in this group of people. Chloroquine is a member of the drug class 4-aminoquinoline. It works against the asexual form of malaria inside the red blood cell. Chloroquine was discovered in 1934. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. It is available as a generic medication. The wholesale cost is about is about 0.04 USD. In the United States it costs about 5.30 USD per dose.