HYQ 400 Tablet contains Hydroxychloroquine sulfate 400 mg, an antimalarial and immunomodulatory agent primarily used for the treatment and prevention of malaria, as well as autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. Hydroxychloroquine acts by increasing the pH within intracellular vacuoles, interfering with lysosomal activity and autophagy, and modulating immune system activity, thereby reducing inflammation and autoimmune responses. It is indicated for acute and chronic malaria caused by Plasmodium species, and for managing symptoms of autoimmune disorders by decreasing joint pain, swelling, and skin manifestations. HYQ 400 Tablet should be administered under medical supervision, with dosage tailored to the specific condition and patient response. Common side effects include gastrointestinal disturbances, headache, dizziness, and skin rashes, while rare but serious adverse effects may involve retinopathy, cardiomyopathy, and hematologic abnormalities, necessitating regular ophthalmologic and clinical monitoring during prolonged therapy. Caution is advised in patients with pre-existing retinal or cardiac conditions, and it is contraindicated in those with hypersensitivity to hydroxychloroquine or related compounds. HYQ 400 Tablet should be used with caution during pregnancy and lactation, only if the potential benefits outweigh risks. Proper adherence to prescribed dosage and monitoring protocols is essential to maximize therapeutic efficacy and minimize toxicity.