Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Antimalarial — Lupus / Dermatoses

Hydroxychloroquine

Brand names: Plaquenil

Hydroxychloroquine is an antimalarial used as a disease-modifying treatment in lupus, rheumatoid arthritis and some skin conditions.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Malaria in Adult and Pediatric Patients ( 2.2 ): ● Prophylaxis: Begin weekly doses 2 weeks prior to travel to the endemic area, continue weekly doses while in the endemic area, and continue the weekly doses for 4 weeks after leaving the endemic area: - Adults: 400 mg once a week - Pediatric patients ≥ 31 kg: 6.5 mg/kg up to 400 mg, once a week ● Treatment of Uncomplicated Malaria: See Full Prescribing Information (FPI) for complete dosing information. Rheumatoid Arthritis in Adults ( 2.3 ): Initial dosage: 400 mg to 600 mg daily Chronic dosage: 200 mg once daily or 400 mg once daily (or in two divided doses) Systemic Lupus Erythematosus in Adults ( 2.4 ): 200 mg once daily or 400 mg once …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-10-09. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It modulates immune and inflammatory responses (including lysosomal and antigen-presentation pathways); the precise mechanism in autoimmune disease is not fully defined.

Prescribing in practice

  • Retinal toxicity is the key long-term risk — baseline and, after a few years, regular ophthalmology screening is recommended, with dose related to body weight.
  • It is among the better-tolerated DMARDs and is generally considered compatible with pregnancy in autoimmune disease (specialist guidance).
  • Use caution with significant QT prolongation or other QT-prolonging drugs and in G6PD deficiency.

Monitoring

Baseline and periodic retinal screening per guidance; weight-based dosing; review skin/joint response.

Counselling the patient

  • Report any change in vision.
  • It can take weeks to months to work.
  • Do not exceed the prescribed dose; overdose is dangerous, especially for children.

Evidence & guidelines

A cornerstone treatment in SLE and an option in rheumatoid arthritis, with retinal-screening monitoring (Royal College of Ophthalmologists guidance).

Reference: MHRA Drug Safety Update (2018) Hydroxychloroquine dose; RCOphth Hydroxychloroquine Guidelines 2020; BAD CLE Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways