Plaquenil (Hydroxychloroquine sulfate) Systemic anti-infective Antimalarial preparation Malaria, systematic lupus erythematosus, rheumatoid arthritis. (Adults) Lupus erythematosus: Initial dose 400 mg 1 or 2 times daily. Rheumatoid arthritis: 200-400 mg/day. Malaria prevention: 400 mg every 7 days 2 weeks before and 8 weeks after trip. Malaria treatment: Initially 800 mg, then 400 mg 6, 24, and 48 hours after 1st dose. Category X Headache, itching, loss of appetite, Diarrhea, Muscle Cramps, eye toxicity. Pregnancy Risk Categories defined: A: Studies in pregnant women failed to show a risk to the fetus in the first trimester - with no evidence of risk in the later trimesters. B: Animals studies indicate no adverse effect to the fetus, but there are no adequate, clinical studies in pregnant women. C: Animal studies have shown an adverse effect on the fetus, but there are no adequate, clinical studies in humans. Despite potential risks, the drug may be useful in pregnant women. D: There is evidence of risk to the human fetus, but the potential benefits of use in pregnant women may be acceptable, despite potential risks. X: Studies in animals or humans show fetal abnormalities, or adverse reaction reports indicate evidence of fetal risk. Warning: the risks involved clearly outweigh any potential benefit from using the drug in pregnant women, regardless of trimester. NR: Not rated (i.e., no information available at this time as to the potential risks or benefits).