Hydroxychloroquine and chloroquine are FDA-approved to treat or prevent malaria. Hydroxychloroquine is also FDA-approved to treat certain auto-immune diseases (lupus, rheumatoid arthritis). It belongs to a class of medications known as disease-modifying antirheumatic drugs (DMARDs). It can reduce skin problems in lupus and prevent swelling/pain in arthritis.
Hydroxychloroquine is not recommended for coronavirus infection, also known as COVID-19, unless you are enrolled in a study.