Hydroxychloroquine is used for treating malaria, autoimmune conditions, such as chronic discoid lupus erythematosus, systemic lupus erythematosus, and rheumatoid arthritis. It comes under a class of drugs called disease-modifying antirheumatic drugs. It is taken orally to treat the conditions.
Hydroxychloroquine - Uses, Dosage, Side Effects, Drug Warnings, and Precautions
Hydroxychloroquine is an antimalarial and immunomodulatory drug used to treat malaria.

Hydroxychloroquine in Lupus Nephritis: Dosage, Effectiveness, and Side Effects
Hydroxychloroquine is approved for the treatment of lupus. In lupus, the immune system attacks healthy cells.