Common side effects include muscle problems, loss of appetite, diarrhea, and skin rash.[1] Serious side effects include problems with vision, muscle damage, seizures, and low blood cell levels.[1] It appears to be safe for use during pregnancy.[1][2] Chloroquine is a member of the drug class 4-aminoquinoline.[1] It works against the asexual form of malaria inside the red blood cell.[1]