Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Aminoquinoline — Malaria Prophylaxis / SLE / Rheumatoid Arthritis

Hydroxychloroquine

Brand names: Plaquenil

Hydroxychloroquine is an antimalarial that is also used as a disease-modifying agent in rheumatoid arthritis and systemic lupus erythematosus (SLE).

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 accumulates in lysosomes and raises intracellular pH, interfering with antigen processing and immune signalling; this immunomodulatory effect underlies its use in autoimmune disease.

Prescribing in practice

  • Long-term use carries a risk of irreversible retinal toxicity — baseline and ongoing annual retinal monitoring is recommended (Royal College of Ophthalmologists), with dose related to body weight.
  • It can prolong the QT interval and has a very long half-life, so effects and interactions persist after stopping.
  • It is generally continued during pregnancy in SLE, where the benefits of disease control are considered to outweigh the risks.

Monitoring

Arrange baseline retinal assessment and annual screening after a defined period of treatment per Royal College of Ophthalmologists guidance, dose according to body weight, and review renal and hepatic function and QT risk where relevant.

Counselling the patient

  • Attend your eye-screening appointments and report any change in vision, such as difficulty reading, missing areas or altered colour vision.
  • Take it as prescribed; the benefit in joint or lupus disease builds gradually over weeks to months.
  • Do not stop it in pregnancy without advice, as continuing usually protects against lupus flares.

Evidence & guidelines

A cornerstone DMARD in SLE that reduces flares and is associated with better outcomes, and an established treatment in rheumatoid arthritis; supported by UK rheumatology and ophthalmology guidance.

Reference: PHE Malaria Prevention Guidelines 2023; BSR Hydroxychloroquine Retinopathy Guidelines; MHRA SPC Plaquenil; RECOVERY Trial 2020; 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