Hydroxychloroquine (Plaquenil) is a disease-modifying antirheumatic drug (DMARD) originally developed as an antimalarial but now used in rheumatoid arthritis to help control inflammation and reduce flares. It is generally less potent than methotrexate, but it has a favorable safety profile, making it useful in mild disease or as part of combination therapy with other DMARDs. Benefits may take several weeks to months to appear, and side effects are usually mild (e.g., stomach upset, skin rash). The most important long-term risk is retinal toxicity, so patients require regular eye exams to monitor vision.