Hydroxychloroquine is a quinolone medicine used for treating and preventing malaria. It is also used as a disease-modifying anti-rheumatic drug (DMARD) to treat autoimmune diseases. It comes in the form of oral tablets that you can only buy through a prescription. It is also available under the brand name Plaquenil among others. It is also available in a generic version, but in some cases, you may not find it in every dosage strength or form as its brand-name alternatives. It is also used as combination therapy along with other drugs.