Hydroxychloroquine Dose and Screening Calculator: mg/kg, Safe Tablets per Week and When to Screen

Last updated: November 2026

Hydroxychloroquine retinopathy is permanent but largely preventable: the risk depends mainly on daily dose per kilogram of real (actual) body weight and on how long the drug has been taken. Enter the dose and weight to check the dose, see how many tablets a week stay within the limit, and find when screening should start.

What the limits are based on

• Hydroxychloroquine: no more than 5 mg/kg real body weight per day (AAO 2016; RCOphth 2020 uses the same figure). Doses above this, longer duration, kidney disease and tamoxifen raise the risk.
• Chloroquine: no more than 2.3 mg/kg real body weight per day; screening starts after 1 year because it is more toxic.
• Screening: AAO: baseline examination, then annual screening after 5 years of use (earlier with risk factors). RCOphth: annual screening after 5 years, or after 1 year if there are additional risk factors (dose over 5 mg/kg/day, eGFR under 60, tamoxifen).
• Tests: SD-OCT and automated visual fields (10-2 white-on-white; add 24-2 or 30-2 in Asian patients, whose damage is often pericentral), with fundus autofluorescence and multifocal ERG when results are doubtful. See hydroxychloroquine screening.

For learning and quick checks only. Confirm any result that changes treatment against your own measurements, the device manufacturer's guidance and current local protocols.

Related: Hydroxychloroquine Retinopathy Screening: Dose, Timing and Tests, Ocular Side Effects of Systemic Drugs (ADRs): Modern and Classic, Screening Schedules: DR Follow-up, ROP in India and Hydroxychloroquine, OCT Macula Reference Card: Normal Thickness, DME and Hole Staging. See all eye calculators and tools.

Key sources

• Marmor MF, Kellner U, Lai TYY, Melles RB, Mieler WF. Recommendations on screening for chloroquine and hydroxychloroquine retinopathy (2016 revision). Ophthalmology. 2016;123:1386-1394
• Yusuf IH, Foot B, Lotery AJ. The Royal College of Ophthalmologists recommendations on monitoring for hydroxychloroquine and chloroquine users in the United Kingdom (2020 revision). Eye. 2021;35:1532-1537
• Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmol. 2014;132:1453-1460