Hydroxychloroquine (Plaquenil) Dose Calculator
Calculate hydroxychloroquine (Plaquenil) dosage by weight for malaria, lupus, and rheumatoid arthritis. Get max safe dose, mg/kg, and retinopathy risk assessment.
About This Calculator
The Hydroxychloroquine Dose Calculator helps clinicians and patients determine the safe daily dosage of hydroxychloroquine (brand name Plaquenil) based on actual body weight. It is used for treating malaria, systemic lupus erythematosus (SLE), and rheumatoid arthritis. The calculator implements the American Academy of Ophthalmology (AAO) 2016 screening guideline recommendation of a maximum safe dose of 5 mg/kg per day to minimize the risk of retinopathy.
The calculator compares the actual prescribed daily dose (in mg) against the weight-based maximum safe dose. It computes the actual dose per kilogram of body weight and classifies it as either within safe limits or exceeding the recommended threshold. The retinopathy risk assessment is based on published AAO data: at ≤ 5 mg/kg, the 10-year retinopathy risk is 2% and 20-year risk is 20%; at > 5 mg/kg, the 10-year risk rises to 10% and 20-year risk to 40%.
For malaria treatment, hydroxychloroquine is typically dosed at 800 mg initially followed by 400 mg at 6, 24, and 48 hours. Prophylaxis uses 400 mg weekly. For lupus and rheumatoid arthritis, the typical dose is 200-400 mg per day. Long-term users should have annual ophthalmologic screening for retinal toxicity.
Disclaimer: This calculator is for informational purposes only and should not replace professional medical judgment. Always consult a qualified healthcare provider for dosing decisions.
Frequently Asked Questions
What is hydroxychloroquine used for?
Hydroxychloroquine (Plaquenil) is used to treat malaria, systemic lupus erythematosus (SLE), and rheumatoid arthritis. It works by inhibiting immune cell activation and slowing inflammation. It was also investigated for COVID-19 but has not been proven effective and the FDA emergency use authorization has been revoked.
What is the maximum safe dose of hydroxychloroquine?
According to the American Academy of Ophthalmology (AAO) 2016 guidelines, the maximum safe dose of hydroxychloroquine is 5 mg/kg of actual body weight. Doses exceeding 5 mg/kg significantly increase the risk of retinopathy — 10-year risk rises from 2% to 10%, and 20-year risk from 20% to 40%.
How is hydroxychloroquine dosed for malaria?
For malaria prophylaxis, hydroxychloroquine is typically dosed at 400 mg weekly starting 2 weeks before travel and continuing for 4 weeks after. For malaria treatment, an initial dose of 800 mg is given, followed by 400 mg at 6, 24, and 48 hours. The maximum safe dose is 5 mg/kg of body weight.
How is hydroxychloroquine dosed for lupus and rheumatoid arthritis?
For lupus (SLE) and rheumatoid arthritis, the typical starting dose is 400 mg per day, which may be reduced to 200-400 mg per day after a few weeks. The dose should not exceed 5 mg/kg of actual body weight to minimize the risk of retinal toxicity.
What is the risk of retinopathy with hydroxychloroquine?
Retinopathy is the most serious side effect of chronic hydroxychloroquine use. At doses of 5 mg/kg or less, the 10-year risk is 2% and 20-year risk is 20%. At doses above 5 mg/kg, the 10-year risk increases to 10% and 20-year risk to 40%. Regular ophthalmologic screening is recommended for patients on long-term therapy.
Is hydroxychloroquine effective for COVID-19?
No, hydroxychloroquine has not been proven effective for COVID-19 treatment or prevention. The FDA revoked its emergency use authorization after studies showed it does not decrease mortality risk and may increase the risk of fatal heart arrhythmias. The WHO also recommends against its use for COVID-19.
What are the side effects of hydroxychloroquine?
Common side effects include nausea, vomiting, diarrhea, and stomach pain. Serious side effects include retinopathy (potentially irreversible vision loss), dangerous heart arrhythmias especially in long QT syndrome, allergic reactions with swelling that may cause breathing difficulties, and fetus malformations during pregnancy.
Can I share my results?
Yes, the URL saves your inputs automatically so you can share the exact calculation with your healthcare provider by copying the page URL.