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Macrolide Antibiotic — Obstetric

Erythromycin (PPROM / GBS in Pregnancy)

Brand names: Erythrocin, Erymax

Erythromycin is a macrolide antibiotic used in obstetrics for preterm prelabour rupture of membranes (PPROM) and as an option in group B streptococcus (GBS) prophylaxis when penicillin is unsuitable.

Dosing — not shown for this use

The product information we hold does not support a dose for this page's specific use, route or population, so none is shown. Follow your local or national guideline, and confirm against the product SmPC.

The licensed dosing — for the medicine's licensed uses, which may differ from this page's — is on Erythromycin.

Clinical monograph

How it works

Inhibits bacterial protein synthesis by binding the 50S ribosomal subunit, giving bacteriostatic activity against many Gram-positive and atypical organisms.

Prescribing in practice

  • Co-amoxiclav should be avoided in PPROM because of the increased risk of neonatal necrotising enterocolitis, so erythromycin is the preferred agent in this setting.
  • Erythromycin prolongs the QT interval and inhibits CYP3A4, so review concurrent QT-prolonging and interacting drugs before prescribing.
  • Gastrointestinal upset is common and may limit tolerability.

Monitoring

Routine laboratory monitoring is not usually required; monitor for gastrointestinal intolerance and review the maternal and neonatal infection picture.

Counselling the patient

  • Nausea, abdominal cramps and diarrhoea are common side effects.
  • Take the course as directed and complete it even if symptoms settle.
  • Report palpitations or fainting, and mention all other medicines being taken.

Evidence & guidelines

NICE guidance on preterm labour recommends erythromycin in PPROM and advises against co-amoxiclav because of the necrotising enterocolitis signal seen in the ORACLE trial.

Reference: NICE NG25 (Preterm Labour and Birth); ORACLE I Trial; RCOG Green-top 44 (PPROM); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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