Antibiotic (Tetracycline) Pregnancy: Contra-indicated in pregnancy and lactation (see contraindications).

Doxycycline

Brand names: Vibramycin, Efracea (low-dose)

Used in: Pneumonia COPD Cellulitis & Skin Infection

Doxycycline is a long-acting tetracycline antibiotic used for respiratory, genitourinary, skin and tick-borne infections, acne and rosacea, and as antimalarial prophylaxis.

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: Acute infections (adults and children 12 to <18 years): 200 mg on the first day (as a single dose or in divided doses), followed by a maintenance dose of 100 mg/day. For more severe infections, 200 mg daily throughout treatment.

Route: Oral

Frequency: Once daily maintenance (loading dose day 1); indication-specific regimens below

Max: Not stated as an absolute ceiling (indication-specific regimens)

Indication-specific regimens: Acne vulgaris 50 mg daily with food/fluid for 6-12 weeks. Sexually transmitted diseases (uncomplicated gonococcal [except anorectal in men]; uncomplicated urethral/endocervical/rectal Chlamydia trachomatis; non-gonococcal urethritis due to Ureaplasma urealyticum) 100 mg twice daily for 7 days. Acute epididymo-orchitis (C. trachomatis or N. gonorrhoeae) 100 mg twice daily for 10 days. Primary and secondary syphilis (non-pregnant, penicillin-allergic) 200 mg twice daily for two weeks. Louse/tick-borne relapsing fever: single 100 mg or 200 mg dose by severity. Chloroquine-resistant falciparum malaria treatment: 200 mg daily for at least 7 days (give with a rapid-acting schizonticide such as quinine). Malaria prophylaxis: 100 mg daily (adults and children over 12), starting 1-2 days before travel, continued during travel and for 4 weeks after leaving the area (consult current national prescribing guidelines / Malaria Reference Laboratory for resistance patterns). Scrub typhus prevention: 200 mg single dose. Travellers' diarrhoea prevention: 200 mg on day 1 (single dose or 100 mg every 12 h) then 100 mg daily. Leptospirosis prevention: 200 mg once weekly during stay plus 200 mg on completing the trip. Rocky Mountain spotted fever: adults 100 mg every 12 hours. Elderly: usual dosages, no special precautions; no dose adjustment in renal impairment.

Paediatric dose

Dose: 4.4 mg/kg

Route: Oral

Frequency: Initial dose 4.4 mg/kg (single or 2 divided doses) on day 1, then maintenance 2.2 mg/kg (single or 2 divided doses); up to 4.4 mg/kg throughout for more severe infections

Max: Children over 45 kg: use the adult dose

Applies to children aged 8 to <12 years weighing 45 kg or less, and only when other drugs are unavailable/ineffective/contraindicated (careful justification required). Children over 45 kg: use the adult dose. CONTRAINDICATED / do NOT use in children under 8 years (risk of permanent tooth discolouration), except severe/life-threatening conditions (e.g. Rocky Mountain spotted fever) with no adequate alternative. Rocky Mountain spotted fever, children <45 kg: 2.2 mg/kg body weight every 12 hours. Paediatric dosing is safety-critical — verify against a current children's formulary.

Dose adjustments

Renal

No dosage adjustment necessary in renal impairment (usual recommended doses do not lead to accumulation)

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.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Hypersensitivity to the active substance, to other tetracyclines, or to any of the excipients
Pregnancy (predominantly effects on teeth and skeletal development)
Nursing mothers (tetracyclines excreted into milk)

Side effects

Gastrointestinal: nausea/vomiting, dyspepsia; (rare) pancreatitis, pseudomembranous/C. difficile colitis, oesophageal ulcer/oesophagitis, dysphagia, diarrhoea
Skin: photosensitivity reaction, rash; serious skin reactions (toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme, exfoliative dermatitis, DRESS)
Hypersensitivity (including anaphylactic shock/reaction, angioedema, urticaria), Jarisch-Herxheimer reaction
Nervous system: headache; benign intracranial hypertension (pseudotumor cerebri), fontanelle bulging
Hepatobiliary: hepatic failure, hepatitis, hepatotoxicity, jaundice; Blood: haemolytic anaemia, neutropenia, thrombocytopenia, eosinophilia; tooth discolouration

Clinical monograph

How it works

It binds reversibly to the bacterial 30S ribosomal subunit, blocking attachment of aminoacyl-tRNA and so inhibiting protein synthesis, producing a bacteriostatic effect.

Prescribing in practice

Contraindicated in pregnancy, breastfeeding and in children under twelve because tetracyclines bind to developing bone and teeth, causing permanent discolouration and enamel hypoplasia.
Photosensitivity is common, so advise sun protection and avoidance of sunbeds during treatment.
Absorption is reduced by calcium, iron, magnesium, zinc, antacids and dairy, so separate these from dosing.

Monitoring

Routine laboratory monitoring is not usually required for short courses, but watch for photosensitivity, gastrointestinal upset and signs of oesophageal irritation.

Counselling the patient

Take with plenty of water while sitting or standing upright and not immediately before lying down to prevent throat and oesophageal irritation.
Use sunscreen and cover up, as your skin may burn more easily.
Complete the full course as prescribed.

Evidence & guidelines

Doxycycline is recommended across NICE antimicrobial guidance for indications including community-acquired pneumonia, chronic obstructive pulmonary disease exacerbations and chlamydia.

Reference: PHE Antibiotic Guidelines; BASHH Chlamydia 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.

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Pathways