Hydroxychloroquine sulfate tablets are used for the treatment of rheumatoid arthritis, juvenile chronic arthritis, discoid and systemic lupus erythematosus, and skin conditions that are triggered and exacerbated by the sun. Patients may experience the following side effects, including retinal changes, which can occur as retinal pigmentation changes and visual field defects, as well as corneal edema and clouding, and skin symptoms such as rash, itching, pigmentation changes, hair graying, and hair loss. It may also cause maculopapular rash, including the very rare erythema multiforme, toxic epidermolysis bullosa, photosensitivity and exfoliative dermatitis, and gastrointestinal disorders such as nausea, diarrhea and anorexia. It may also cause central nervous system side effects, including dizziness, vertigo, tinnitus, hearing loss, headache, hypersensitivity and emotional instability, psychosis, and suicidal behavior. It may also cause sensory-motor nerve disorders, as well as cardiomyopathy, bone marrow suppression, abnormal liver function tests, hypokalemia, etc. Therefore, you need to pay attention to the observation when using the drug and seek medical attention promptly if you have any uncomfortable symptoms.