Anti-inflammatory / Antimicrobial Pregnancy: In leprosy, benefits are generally considered to outweigh potential risk; some leprologists recommend folic acid 5 mg daily supplementation during pregnancy. Excreted in breast milk (a report of haemolytic anaemia in a breast-fed infant). (Note: derived from oral tablet SPC.)

Dapsone

Brand names: Aczone (topical), Dapsone (oral — systemic indications)

Topical dapsone is a gel formulation of the sulfone antibacterial applied to the skin for inflammatory acne vulgaris.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 100 mg (leprosy); 50 mg initially (dermatitis herpetiformis)

Route: Oral

Frequency: Daily (regimen varies by indication)

NOTE: bundle contains the UK ORAL tablet SPC (Dapsone 100 mg Tablets), not a topical (e.g. gel) product — no topical posology is available in the source; clinician to source dedicated topical dapsone labelling if a topical formulation is intended. Oral tablet data below, for adults and children over 12 years. Multibacillary leprosy (3-drug regimen): 100 mg daily for at least two years. Paucibacillary leprosy (2-drug regimen): 100 mg daily for at least 6 months. Malaria prophylaxis: 100 mg weekly with 12.5 mg pyrimethamine. Dermatitis herpetiformis: initially 50 mg daily, gradually increasing to 300 mg daily if required, then reduce to a minimum (usually 25-50 mg daily). Pneumocystis carinii (jirovecii) pneumonia: with trimethoprim, 50-100 mg daily; or 100 mg twice weekly, or 200 mg once weekly. Elderly: reduce dose where there is hepatic impairment. Paediatric (children 6-12 years, leprosy): 50 mg daily; children under 6 years: not established, no data.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to dapsone, sulfonamides, sulfones, or to any of the excipients
Severe anaemia
Porphyria
Severe glucose-6-phosphate dehydrogenase (G6PD) deficiency

Side effects

Haemolysis and methaemoglobinaemia (dose-related, most frequent); haemolytic anaemia
Agranulocytosis (rare)
Dapsone syndrome (rash, fever, eosinophilia; can progress to exfoliative dermatitis, hepatitis, psychosis; deaths recorded)
Peripheral and peripheral motor neuropathy
Hepatitis, jaundice, changes in liver function tests

Interactions

Oral typhoid vaccine: do not take until at least three days after finishing a course of dapsone
Probenecid: reduces dapsone excretion and increases dapsone plasma concentrations
Rifampicin / rifabutin: increases plasma clearance of dapsone
Saquinavir: should not be used in combination (risk of irregular heartbeat)
Trimethoprim: increased dapsone and trimethoprim concentrations reported on concurrent administration

Clinical monograph

How it works

Applied locally it exerts anti-inflammatory and antimicrobial effects, attenuating the neutrophilic inflammation that characterises inflammatory acne lesions.

Prescribing in practice

A transient yellow-orange skin or hair discolouration can occur where the gel contacts benzoyl peroxide, so the two should not be applied at the same time.
Systemic absorption is low, so the haematological risks seen with oral dapsone are not generally expected with topical use.
Confine application to the affected skin and avoid the eyes, lips and mucous membranes.

Monitoring

Routine blood monitoring is not required for topical use; assess the treated skin for irritation and therapeutic response at review.

Counselling the patient

Apply a thin film to clean, dry affected skin and wash your hands afterwards.
Do not use benzoyl peroxide products at the same time of day, as together they may temporarily stain skin or hair orange.
Mild dryness, redness or stinging may occur initially and usually settles.

Evidence & guidelines

Topical dapsone gel has demonstrated efficacy for inflammatory acne in randomised controlled trials underpinning its licence.

Reference: BAD Dermatitis Herpetiformis Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways