The U.S. Food and Drug Administration (FDA) has approved antimalarial agents for treatment of one skin condition, lupus erythematosus. A chronic, inflammatory autoimmune disorder, lupus erythematosus often causes a "butterfly" rash over the cheeks and bridge of the nose made worse by sun exposure. Antimalarial agents are sometimes used to treat this condition in patients who do not respond to other measures, including sunscreens and topical corticosteroids. Antimalarial agents have been shown to improve skin problems, joint problems and ulcers associated with the condition.

Physicians also sometimes prescribe antimalarial medications, such as hydroxychloroquine or chloroquine phosphate, to treat other conditions that affect the skin. These disorders include:

• Solar urticaria. Hives that appear on parts of the body within a few minutes of exposure to the sun.
  
  
• Morphea. A rare, localized form of scleroderma marked by oval-shaped patches that are red or purple and that often develop a whitish center.
  
  
• Sjögren syndrome. A disorder of the immune system that causes symptoms such as dry eyes, dry mouth, and skin rash or dry skin (xerosis). Hydroxychloroquine is sometimes prescribed to treat this condition.
  
  
• Sarcoidosis. Disease in which inflammation occurs in the skin, lymph nodes, lungs, liver, eyes or other tissues.
  
  
• Dermatomyositis. A rare disease marked by muscle weakness and a skin rash. Antimalarial medications are sometimes prescribed to treat cases of persistent rash.
  
  
• Porphyria cutanea tarda. Characterized by sensitivity to the sun, this condition results from underactivity of the enzyme uroporphyrinogen decarboxylase (UROD). Individuals with this condition develop blistering, scarring, changes in pigmentation and increased hair growth when their skin is exposed to the sun.

Aside from their use in treating various skin-related conditions, antimalarial agents are chiefly used to treat or prevent malaria. This disease occurs when humans are infected by a single-celled parasite (Plasmodium) through a mosquito bite. There are only four species of the Plasmodium parasite that can cause malaria. They live in mosquitoes in tropical and subtropical areas of Africa, Asia, and Central and South America. Patients with malaria experience fever and chills that comes in recurrent attacks. Left untreated, the disease can be deadly.