Hydroxychloroquine 200 mg is a medication that belongs to the class of drugs known as antimalarials. It is commonly used for the treatment and prevention of malaria, a parasitic infection transmitted by mosquitoes. Additionally, hydroxychloroquine is prescribed for the management of certain autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis.

Hydroxychloroquine works by interfering with the growth and reproduction of parasites within the body. It is believed to affect their ability to utilize certain substances necessary for their survival. In the case of autoimmune diseases, hydroxychloroquine's precise mechanism of action is not fully understood, but it is thought to modulate the immune response and reduce inflammation.