Tetracycline antibiotic Pregnancy: Should not be administered to pregnant women — tetracyclines readily cross the placental barrier and are selectively absorbed by developing bones and teeth, and may cause dental dyschromia and enamel hypoplasia. Breast-feeding: should not be administered to breast-feeding women (tetracyclines are distributed into milk; risk of enamel hypoplasia or dental dyschromia in the infant). Fertility: no data available.

Lymecycline

Brand names: Tetralysal 300

Lymecycline is an oral tetracycline antibiotic used mainly for moderate inflammatory acne vulgaris and sometimes rosacea.

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: 408 mg (one capsule) once daily for chronic treatment of acne; for other infections 408 mg (one capsule) twice a day

Route: Oral

Frequency: Once daily (acne) or twice daily (other infections)

Max: Where higher doses are required, 3–4 capsules (1224 mg – 1632 mg) may be given over 24 hours

Source product: Lymecycline 408 mg Capsules, hard. For acne, treatment should be continued for at least eight (8) weeks. In the management of sexually transmitted disease, both partners should be treated. Capsules should always be taken with a glass of water (to avoid oesophageal irritation and ulceration). Elderly: no specific dosage adjustment required. Hepatic impairment: use with caution — potential for accumulation with increased toxicity. Paediatric: safety and efficacy in children under 12 years have not been established and no data are available; for children over the age of 12 years the adult dosage may be given (no per-kg dose is stated). Contraindicated in children less than 8 years due to risk of permanent dental staining and enamel hypoplasia, and the product should not be used below 12 years for the same reason. Avoid direct sunlight and ultraviolet light during treatment (photosensitivity); discontinue if erythematous cutaneous manifestations occur.

Dose adjustments

Renal

Contraindicated in patients with overt renal insufficiency; caution if renal function is impaired.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or any other tetracycline, or to any of the excipients
Overt renal insufficiency
Children less than 8 years of age (risk of permanent dental staining and enamel hypoplasia)
Concurrent treatment with oral retinoids

Side effects

Nausea, abdominal pain and diarrhoea (common)
Headache (common); dizziness and intracranial hypertension (not known)
Hepatobiliary: jaundice, hepatitis, raised transaminases/alkaline phosphatase/bilirubin (not known)
Skin: erythematous rash, photosensitivity, pruritus, Stevens-Johnson syndrome (not known)
Immune: anaphylactic reaction, hypersensitivity, urticaria, angioneurotic oedema (not known); also neutropenia and thrombocytopenia

Interactions

Iron preparations, antacids (magnesium/aluminium and calcium hydroxides, oxides, salts), cholestyramine, bismuth chelates, sucralfate and quinapril may decrease cycline absorption — do not take within 2 hours before or after lymecycline
Enzyme inducers (barbiturates, carbamazepine, phenytoin) may accelerate tetracycline decomposition via hepatic enzyme induction, decreasing its half-life
Lithium — combination may cause an increase in serum lithium levels
Oral retinoids and vitamin A above 10 000 IU/day — avoid; increased risk of benign intracranial hypertension
Anticoagulants — effects may be increased, with increased risk of haemorrhage
Diuretics — concomitant use should be avoided
Absorption is not significantly impaired by moderate amounts of milk (unlike earlier tetracyclines)

Clinical monograph

How it works

It inhibits bacterial protein synthesis by binding the 30S ribosomal subunit and also has anti-inflammatory effects relevant to acne, including activity against Cutibacterium acnes.

Prescribing in practice

Contraindicated in pregnancy, breastfeeding and in children under twelve because tetracyclines cause permanent dental discolouration and affect bone development; avoid in this group.
It should not be taken at the same time as antacids, or iron, calcium, magnesium or zinc salts, which impair absorption through chelation.
An adequate trial of several weeks is needed before judging response in acne, and benefit-risk should be reviewed for prolonged courses.

Monitoring

Monitor for clinical response and for adverse effects such as photosensitivity, gastrointestinal upset and, rarely, intracranial hypertension.

Counselling the patient

Do not take if you are or could be pregnant, or if breastfeeding.
Separate the capsule from indigestion remedies and iron, calcium or zinc supplements.
Use sun protection, and seek urgent advice for severe headache with visual disturbance.

Evidence & guidelines

Oral tetracyclines including lymecycline are recommended in NICE guidance as an option for moderate-to-severe acne vulgaris, generally combined with a topical agent.

Reference: NICE NG198; BAD acne guidance; 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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