Oral tetracycline antibiotic (anti-acne / anti-rosacea) Pregnancy: Avoid in second and third trimester — dental staining and bone effects in fetus. Use erythromycin or clindamycin topically instead.

Doxycycline 100mg (Acne / Rosacea)

Brand names: Efracea (40mg MR — rosacea), Vibramycin-D, Doxycycline (generic)

Adult dose

Dose: 100 mg once daily

Route: Oral (with food and a full glass of water — reduce oesophageal irritation)

Frequency: Once daily

Max: 100 mg/day for acne/rosacea

Acne vulgaris: 100 mg OD (not BD — BNF recommends 100 mg OD for acne, not the higher infection doses). Minimum course 3 months; may be required 6–12 months. For rosacea (papulopustular): doxycycline 40 mg MR (Efracea) OD — anti-inflammatory dose, not antibiotic. Swallow upright, do not lie down for 30 min post-dose.

Paediatric dose

Route: Oral

Frequency: Once daily

Max: Not recommended in children <12 years (tooth discolouration and bone effects)

Contraindicated in children under 12 years. In children ≥12 years with severe acne: same adult dose 100 mg OD. Avoid concurrent retinoids (raised ICP risk).

Dose adjustments

Renal

No dose adjustment required — unlike many tetracyclines, doxycycline is largely faecally excreted.

Hepatic

Use with caution in hepatic impairment; avoid prolonged use.

Clinical pearls

BNF acne dose is 100 mg OD — not 100 mg BD (the higher dose is for infections, not acne)
Combine with topical benzoyl peroxide (e.g., PanOxyl) to prevent C. acnes antibiotic resistance — NICE and BAD recommendation
Photosensitivity: advise broad-spectrum SPF30+ daily — significant risk in UK summers and abroad
Oesophageal ulceration prevention: always take with a full glass of water and remain upright for at least 30 min
For rosacea: Efracea 40 mg MR is a sub-antimicrobial dose — anti-inflammatory action without selecting resistance

Contraindications

Children under 12 years (dental staining, bone effects)
Pregnancy (second and third trimester — tooth discolouration)
Breastfeeding
Concurrent retinoids (isotretinoin, acitretin) — raised intracranial pressure risk
Hypersensitivity to tetracyclines

Side effects

GI upset (nausea, vomiting — take with food)
Oesophageal ulceration (take with full glass of water, remain upright)
Photosensitivity (advise sun protection — SPF30+)
Vaginal candidiasis (prolonged use)
Pseudotumour cerebri (raised ICP — especially with retinoids)
Antibiotic resistance (prolonged use — combine with topical benzoyl peroxide to reduce resistance)

Interactions

Isotretinoin / acitretin — contraindicated (pseudotumour cerebri)
Antacids (calcium, magnesium, iron, aluminium) — chelation reduces absorption — separate by 2h
Oral contraceptives — theoretical reduced efficacy (no strong evidence, advise barrier contraception)
Warfarin — may enhance anticoagulant effect — monitor INR

Monitoring

Clinical acne response (after 3 months)
Symptoms of raised ICP (headache, visual changes)
Photosensitivity reactions

Reference: BNFc; BNF; NICE CG184 Acne Vulgaris; BAD Acne Guidelines 2021; BAD Rosacea Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways