Plaquenil (hydroxychloroquine) is used to treat or prevent malaria, a disease caused by parasites that enter the body through the bite of a mosquito. Hydroxychloroquine is not effective against all strains of malaria, or against malaria in areas where the infection has been resistant to a similar drug called chloroquine.
Plaquenil is also used to treat symptoms of rheumatoid arthritis and discoid or systemic lupus erythematosus.
