Oral tetracycline antibiotic Pregnancy: Avoid in second and third trimester. Use amoxicillin or erythromycin for CAP/COPD exacerbation in pregnancy.

Doxycycline (COPD Exacerbation / CAP)

Brand names: Vibramycin-D, Doxycycline (generic)

Adult dose

Dose: 200 mg loading dose on day 1, then 100 mg once daily for 5 days (total 5-day course)

Route: Oral (with food and water — reduce oesophageal irritation)

Frequency: 200 mg day 1, then 100 mg OD days 2–5

Max: 200 mg/day loading; 100 mg/day maintenance

COPD acute exacerbation: 5-day course (NICE NG115). Community-acquired pneumonia (CAP): 200 mg day 1 then 100 mg OD for 5–7 days. Indications: penicillin allergy, atypical pathogens (Mycoplasma, Chlamydophila pneumoniae, Legionella — combined with beta-lactam for Legionella). Swallow upright with full glass of water. Avoid dairy or antacids within 2h.

Paediatric dose

Route: Oral

Frequency: As per adult schedule

Max: Not recommended <12 years (dental/bone effects)

Contraindicated under 12 years. Adolescents ≥12 years: adult dosing.

Dose adjustments

Renal

No dose adjustment required — faecally excreted (unlike most tetracyclines).

Hepatic

Use with caution in hepatic impairment.

Clinical pearls

First-line alternative to amoxicillin in penicillin-allergic patients with COPD exacerbation or CAP (NICE NG120 and NG115)
Covers atypical organisms: Mycoplasma pneumoniae, Chlamydophila pneumoniae — important in CAP and useful in younger patients with 'walking pneumonia'
Oesophageal ulceration prevention: always take with a full glass of water (at least 200 mL) and remain upright for 30 min
Photosensitivity: advise SPF30+ sunscreen throughout course and for 2 weeks after
Renal-safe tetracycline: unlike oxytetracycline/tetracycline, doxycycline is safe in renal impairment — faecally excreted

Contraindications

Children under 12 years
Pregnancy (second and third trimester)
Breastfeeding
Concurrent isotretinoin or systemic retinoids
Hypersensitivity to tetracyclines

Side effects

GI upset (nausea, vomiting — take with food)
Oesophageal ulceration (take with full glass of water, remain upright 30 min)
Photosensitivity
Vaginal candidiasis
Pseudotumour cerebri (with concurrent retinoids)

Interactions

Antacids (Ca, Mg, Al, iron) — chelation reduces absorption; separate by 2h
Warfarin — possible enhanced anticoagulation; monitor INR
Retinoids — contraindicated (raised ICP)

Monitoring

Clinical response at 48–72 hours
Photosensitivity reactions
Signs of oesophageal irritation

Reference: BNFc; BNF; NICE NG120 Pneumonia; NICE NG115 COPD; NICE CKS Chest Infection. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways