Hetquenil 400 Tablet contains Hydroxychloroquine 400 mg, an antimalarial and immunomodulatory agent primarily used in the treatment and prevention of malaria, as well as autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. Hydroxychloroquine acts by interfering with lysosomal activity and autophagy, modulating the immune response and reducing inflammation. It is indicated for the management of acute and chronic malaria caused by Plasmodium species and as a disease-modifying antirheumatic drug (DMARD) to alleviate symptoms and prevent disease progression in autoimmune conditions. The tablet should be administered orally, with dosage tailored according to the specific condition, patient weight, and clinical response, typically under medical supervision. Common adverse effects include gastrointestinal disturbances, headache, dizziness, and skin reactions; however, serious side effects such as retinopathy necessitate regular ophthalmologic monitoring during prolonged therapy. Caution is advised in patients with pre-existing retinal or visual field changes, hepatic or renal impairment, and those on concomitant medications that may prolong the QT interval. Hetquenil 400 is contraindicated in patients with hypersensitivity to hydroxychloroquine or related compounds. Proper use and adherence to prescribed dosage are essential to maximize therapeutic benefits and minimize risks.