An antimalarial drug widely used as a DMARD for the treatment of rheumatoid arthritis and systemic lupus erythematosus (SLE). Hydroxychloroquine is considered one of the safest DMARDs with a favorable side effect profile and is recommended in virtually all SLE patients unless contraindicated. It is often used in combination with methotrexate in RA.
Retinal toxicity (bull's-eye maculopathy with long-term use)
Known hypersensitivity to hydroxychloroquine or 4-aminoquinolines1,2
Pre-existing retinal or macular disease
The bottom line
Evidence rating strong. Most-documented uses: disease modification in rheumatoid arthritis, essential therapy in systemic lupus erythematosus, improved survival in sle patients. 10 sources indexed (2020–2025), with 2 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Accumulates in lysosomes and raises intralysosomal pH, inhibiting antigen processing and presentation through MHC class II molecules. This reduces T-cell activation and the downstream inflammatory cascade. Hydroxychloroquine also inhibits Toll-like receptor (TLR7 and TLR9) signaling, reducing type I interferon and pro-inflammatory cytokine production. Additional effects include inhibition of phospholipase A2 and platelet aggregation.
Class
Disease-Modifying Antirheumatic Drug (DMARD)
Absorption
Water-soluble; take with food
Dosing
Dosing & protocol.
Common range
200–400 mg daily (not exceeding 5 mg/kg/day to minimize retinal toxicity) (as prescribed by your physician)
Recommended form
Tablet
Take with food or milk to reduce GI side effects; very long tissue half-life means steady state takes months
Safety
Full safety detail.
Side effects
Nausea and GI upset
Skin rash and hyperpigmentation
Retinal toxicity (bull's-eye maculopathy with long-term use)
Headache
Dizziness
QT prolongation (rare)
Myopathy (rare, with long-term use)
Cardiomyopathy (very rare)
Contraindications
Known hypersensitivity to hydroxychloroquine or 4-aminoquinolines1,2
Pre-existing retinal or macular disease
Significant visual field changes from prior 4-aminoquinoline use
Long QT syndrome or concurrent QT-prolonging medications2
Hydroxychloroquine can prolong the QT interval, especially when other risk factors are present. Low potassium is a major modifiable risk factor for torsades de pointes with QT-prolonging drugs. Potassium supplementation is only appropriate when potassium is low or intake is inadequate; excessive potassium can be dangerous, especially with kidney disease or RAAS-blocking drugs.
Recommendation: Keep potassium in the normal range while taking hydroxychloroquine, particularly if you use diuretics or have vomiting or diarrhea. Do not start potassium tablets or high-dose electrolyte powders unless your clinician is monitoring potassium and kidney function. Seek urgent care for fainting, near-fainting, or sustained new palpitations.
Hydroxychloroquine can prolong QTc, and low magnesium makes torsades de pointes more likely when QT risk factors stack. Magnesium supplementation should be viewed as deficiency prevention or repletion, not as a booster for hydroxychloroquine. High-dose magnesium can cause diarrhea and can accumulate in significant kidney disease.
Recommendation: Maintain normal magnesium status while taking hydroxychloroquine, especially if you use diuretics, proton pump inhibitors, or have chronic diarrhea. Ask your clinician whether magnesium should be checked if you have arrhythmia symptoms or multiple QT-risk medicines. Do not use high-dose magnesium if kidney function is reduced unless it is being monitored.
Setty MJ, Kavi RK, Sulthana P et al.. Psychiatric Adverse Effects From Hydroxychloroquine Use: A Systematic Review. The primary care companion for CNS disorders. 2025
Berman A, Kenet G, Lubetsky A et al.. Hydroxychloroquine and pregnancy outcomes in patients with anti-phospholipid syndrome: a systematic review and meta-analysis. RMD open. 2025
Garcia MC, Tsang K, Lohit S et al.. Hydroxychloroquine-Chloroquine, QT-Prolongation, and Major Adverse Cardiac Events: A Meta-analysis and Scoping Review. The Annals of pharmacotherapy. 2024
Zhang Z, Liu X, Ye P et al.. Efficacy and Safety of Hydroxychloroquine in Patients with IgA Nephropathy: A Meta-Analysis. Archivos espanoles de urologia. 2024
Fernandes CP, Vernier LS, Dallegrave E et al.. The Ototoxicity of Chloroquine and Hydroxychloroquine: A Systematic Review. International archives of otorhinolaryngology. 2022
Sharma AN, Mesinkovska NA, Paravar T. Characterizing the adverse dermatologic effects of hydroxychloroquine: A systematic review. Journal of the American Academy of Dermatology. 2020
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