Hydroxychloroquine is an antimalarial drug used to treat uncomplicated cases of malaria and for chemoprophylaxis in certain regions. Hydroxychloroquine also belongs to the group of so-called "disease modifying anti-rheumatic drugs" (DMARDs), which is why it is also used to treat rheumatoid arthritis and lupus erythematosus. It is taken by mouth, often in the form of hydroxychloroquine sulfate.
Hydroxychloroquine has also been studied for its suitability in the prevention and treatment of 2019 coronavirus disease (COVID-19). However, it proved ineffective for this indication in clinical trials.
After World War I, governments worldwide sought alternatives to quinine extracted from the cinchona tree, which until then was the only known antimalarial agent. In 1934, German researchers at Bayer discovered chloroquine, a synthetic analogue with the same mechanism of action. In 1947, in the search for other structural analogues with improved properties, the substance hydroxychloroquine was finally produced. It was approved for medical use in the United States in 1955 and is on the World Health Organization's list of essential medicines.