Hydroxychloroquine as immune system modulator 1 continued to search for equally effective treatments without adverse effects. 1,2 Chloroquine was the first artificially synthesized quinine analogue used as an antimalarial drug. However, it also showed an adverse safety profile. Toxic effects included cutaneous and intestinal complications, cardiac damage, retinopathy, and myelopathy. More advanced forms of antimalarial drugs, mepacrine and hydroxychloroquine (HCQ), were not used until the 20th century. 3 During World War II, millions of soldiers took chloroquine and HCQ as part of a program testing the synthetic derivatives of 4 -aminoquinolines for the prevention of inflammatory cutaneous lesions and arthritis. This led to research confirming the effectiveness of antimalarial drugs in the treatment of systemic lupus erythematosus (SLE).In 1955, HCQ was approved for use in the United States. This synthetic form of quinine lacked Introduction Antimalarial drugs are currently being rediscovered and increasingly appreciated for their properties. Historically, they have been known for about 400 years, and the first antimalarial drug was quinine, an alkaloid produced from the bark of the Cinchona tree in South America. Quinine was originally used as a drug that inhibited proper cell functioning by forming a complex with DNA of the malaria -causing parasite Plasmodium falciparum. It also had additional antipyretic and analgesic effects, which was particularly important in medicine at that time. The use of quinine for an indication other than malaria was first described by Payne in 1894, when he reported successful treatment of cutaneous lupus manifestations. As an antiprotozoal drug, quinine carried the risk of complications, especially neurotoxic ones, such as vision and hearing disorders. Therefore, investigators