Tetracycline Antibiotic — Anti-inflammatory (Ocular Rosacea / MGD) Pregnancy: Avoid from second trimester — permanent dental staining of fetal teeth; maternal hepatotoxicity risk

Doxycycline (Systemic — Ocular Rosacea / Blepharitis)

Brand names: Vibramycin, Efracea (low-dose licensed for rosacea)

Adult dose

Dose: 40 mg modified release once daily (Efracea — licensed for rosacea); 100 mg once daily for 6–8 weeks then 50 mg maintenance (off-label for blepharitis/MGD)

Route: Oral

Frequency: Once daily

Max: 100 mg/day (off-label ocular use); 40 mg (licensed Efracea for rosacea)

Used systemically for ocular rosacea, meibomian gland dysfunction (MGD), and chronic blepharitis. Anti-inflammatory rather than antibacterial mechanism at low doses — inhibits matrix metalloproteinases (MMPs), reduces eyelid margin inflammation. Take with food and full glass of water; remain upright for 30 minutes.

Paediatric dose

Route:

Avoid in children under 12 years — tetracyclines cause permanent tooth discolouration and inhibit bone growth in children under 8 years; under 12 is cautious approach in UK

Dose adjustments

Renal

No dose adjustment required — doxycycline is excreted via gut even in renal failure (unlike tetracycline — use doxycycline in renal impairment if tetracycline class is needed)

Hepatic

Reduce dose or increase interval in severe hepatic impairment

Clinical pearls

Anti-inflammatory mechanism at low doses: sub-antimicrobial doxycycline (40 mg — Efracea) acts primarily via MMP inhibition rather than direct antibacterial activity — reduces meibomian gland inflammation, improves meibum quality, and decreases tear film evaporation in MGD without selection pressure for antibiotic resistance
Ocular rosacea-blepharitis link: rosacea affects eyelids in 50–70% of cases (sebaceous gland involvement — meibomian glands are modified sebaceous glands); systemic doxycycline is first-line systemic treatment for ocular rosacea/severe MGD
Oesophageal ulceration prevention: patients MUST be counselled to take doxycycline with a full glass of water and remain upright for 30 minutes — multiple cases of oesophageal ulceration and stricture have been reported from patients taking tablets immediately before bedtime without adequate fluid
Photosensitivity: patients must use SPF 30+ sunscreen daily — particularly relevant for outdoor workers; phototoxic reaction (not true allergy) can be severe
Retinoid combination: MHRA explicitly contraindicated doxycycline (and all tetracyclines) with systemic retinoids (isotretinoin for acne, acitretin for psoriasis) — combined risk of benign intracranial hypertension (BIH/IIH) with papilloedema and visual field loss

Contraindications

Children under 8 years — dental staining and bone growth inhibition
Pregnancy (second and third trimester) — dental toxicity to fetus
Hypersensitivity to tetracyclines

Side effects

GI effects — nausea, oesophageal ulceration if taken supine or without food; take with large glass of water and remain upright
Photosensitivity — phototoxic rash; advise high-SPF sunscreen
Oesophageal stricture (rare — if tablets taken without adequate fluid)
Vestibular disturbances — dizziness, vertigo (minocycline more than doxycycline)
Intracranial hypertension (pseudotumour cerebri — rare; with concurrent systemic retinoids)

Interactions

Antacids, calcium, iron, dairy products — chelate doxycycline; reduce absorption by up to 80%; separate by 2–3 hours
Warfarin — doxycycline inhibits vitamin K-producing gut flora; increased INR; monitor
Systemic retinoids (isotretinoin, acitretin) — CONTRAINDICATED combination; additive risk of benign intracranial hypertension (pseudotumour cerebri)

Monitoring

IOP and fundus if headache develops (BIH risk with prolonged use)
LFTs if prolonged use
Symptom response — eyelid inflammation and dry eye at 8–12 weeks
GI tolerability

Reference: BNFc; BNF 90; DEWS II Blepharitis Guidelines; NICE Rosacea Guidance; MHRA Tetracycline + Retinoid Warning; SPC Efracea / Vibramycin. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways