Hydroxychloroquine Side Effects and Monitoring

Standard Dosing and Side Effects

The American College of Rheumatology recommends a dose of 200 mg twice daily (400 mg/day total) for dermatomyositis and other rheumatologic conditions, with a maximum of 5 mg/kg/day to minimize retinal toxicity risk, as reported by the Mayo Clinic Proceedings 1
Gastrointestinal disturbance, headache, dizziness, blurred vision, and pruritus are common side effects that generally do not require discontinuation, according to the MMWR Recommendations and Reports 2
Vortex keratopathy (corneal deposits) is a side effect, as reported by the Journal of the National Comprehensive Cancer Network : JNCCN 3, 4, 5, 6
QT prolongation is a potential side effect, with baseline ECG recommended, as reported by the Mayo Clinic Proceedings 1
Exacerbation of psoriasis is a potential side effect, according to the MMWR Recommendations and Reports 2
Rare side effects include rash, elevated liver enzymes, and diarrhea, as reported by Military Medical Research 7

Chloroquine retinopathy with potential vision loss is the most serious long-term adverse effect, occurring with prolonged use beyond 2 years, as reported by the Journal of the National Comprehensive Cancer Network : JNCCN 3, 4, 5, 6
Baseline ophthalmologic examination is mandatory before initiating therapy, with annual screening beginning after 5 years for low-risk patients, although the exact recommendation is not cited, periodic ophthalmologic examinations are essential for extended use (>6 years cumulative weekly prophylaxis), as reported by the MMWR Recommendations and Reports 2

The American College of Rheumatology recommends a maximum daily dose of 5 mg/kg based on actual body weight to minimize retinal toxicity risk, with daily doses exceeding this limit increasing the risk of retinopathy 8
The European League Against Rheumatism suggests that hydroxychloroquine is recommended for all patients with systemic lupus erythematosus due to multiple beneficial effects, at a dose of 200 mg once daily or 400 mg once daily or in two divided doses 9, 10

For dermatomyositis, the Mayo Clinic recommends a dose of 200 mg twice daily, which is equivalent to 5 mg/kg 11

The American Academy of Ophthalmology recommends baseline examination and annual screening beginning after 5 years of therapy for low-risk patients, with earlier and more frequent screening for high-risk patients 8
The National Kidney Foundation recommends checking G6PD levels in men of African, Asian, or Middle Eastern origin before starting treatment, and reducing the dose by 25% in patients with eGFR <30 ml/min per 1.73 m² 12

The World Health Organization states that current evidence does not support routine use of hydroxychloroquine for COVID-19 treatment 13
The Centers for Disease Control and Prevention investigated hydroxychloroquine for COVID-19 treatment in 2020, with proposed dosing regimens including a 600 mg loading dose, 300 mg 12 hours later, followed by 300 mg twice daily on days 2-5 14, 15, 16

The Centers for Disease Control and Prevention recommends that hydroxychloroquine is absolutely contraindicated in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, as well as pre-existing retinal or visual field deficits 17

The American Academy of Dermatology notes that hydroxychloroquine can exacerbate psoriasis, with cases of psoriasis flare reported with antimalarial medications 18, 19
The Centers for Disease Control and Prevention warns that photohypersensitivity to sunlight is a potential side effect of hydroxychloroquine 17

The Centers for Disease Control and Prevention recommends monthly hydroxychloroquine plasma level monitoring for chronic Q fever treatment, with a target level of 0.8-1.2 μg/mL 17