Hydroxychloroquine, sold under the brand name Plaquenil among others, is a medication used to prevent and treat malaria in areas where malaria remains sensitive to chloroquine. Other uses include treatment of rheumatoid arthritis, lupus, and porphyria cutanea tarda. It is taken by mouth, often in the form of hydroxychloroquine sulfate. Hydroxychloroquine was approved for medical use in the United States in 1955. hydroxychloroquine structure It is on the World Health Organization’s List of Essential Medicines. In 2019, it was the 122nd most commonly prescribed medication in the United States, hydroxychloroquine uses with more than 5 million prescriptions. hydroxychloroquine suppliers.