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Macrolide Antibiotic — Obstetric Pregnancy: Safe in pregnancy; preferred macrolide for PPROM per NICE NG25

Erythromycin (PPROM / GBS in Pregnancy)

Brand names: Erythrocin, Erymax

Adult dose

Dose: PPROM: 250 mg four times daily for 10 days (or 500 mg three times daily). GBS prophylaxis (penicillin allergy, clindamycin-resistant): 500 mg IV every 6 hours intrapartum
Route: Oral / Intravenous
Frequency: Four times daily (oral); every 6 hours (IV intrapartum)
Max: 4 g/day
ORACLE I trial: oral erythromycin + co-amoxiclav for PPROM — erythromycin alone preferred (co-amoxiclav associated with increased neonatal necrotising enterocolitis). NICE NG25: erythromycin for 10 days in PPROM

Paediatric dose

Dose: Not applicable in this obstetric context N/A/kg
Route: Oral
Frequency: N/A
Max: N/A
Maternal medication

Dose adjustments

Renal

No dose adjustment required

Hepatic

Use with caution — hepatotoxicity risk with prolonged use

Paediatric weight-based calculator

Maternal medication

Clinical pearls

  • ORACLE I trial (NEJM 2001): erythromycin alone for 10 days in PPROM prolongs pregnancy, reduces neonatal infection, and reduces morbidity — co-amoxiclav arm associated with neonatal NEC and should NOT be used in PPROM
  • PPROM management: antenatal corticosteroids (betamethasone) + erythromycin + expectant management until 34 weeks (or earlier if complications) — RCOG Green-top 44
  • GBS intrapartum prophylaxis: benzylpenicillin IV is first-line; erythromycin is a fallback for penicillin allergy when clindamycin sensitivity not confirmed — check local GBS resistance data
  • GI side effects are the major tolerability issue — take with food; clarithromycin has better GI tolerability but erythromycin is preferred in pregnancy due to longer safety data
  • CYP3A4 inhibitor: erythromycin has more drug interactions than azithromycin — review all concurrent medications when prescribing in pregnancy

Contraindications

  • QT prolongation
  • Concurrent pimozide or ergotamine use

Side effects

  • GI upset (very common — nausea, vomiting, abdominal cramps)
  • QT prolongation
  • Hepatotoxicity (prolonged use)
  • Ototoxicity (high doses IV — rare)

Interactions

  • Warfarin (significantly increases INR — monitor)
  • Statins (CYP3A4 inhibition — myopathy risk)
  • QT-prolonging drugs (additive)
  • Ergotamine (ergotism — contraindicated)

Monitoring

  • QTc (if risk factors)
  • LFTs (prolonged use)
  • Fetal wellbeing (PPROM — CTG, biophysical profile)
  • Signs of infection (chorioamnionitis)

Reference: BNFc; BNF 90; NICE NG25 (Preterm Labour and Birth); ORACLE I Trial; RCOG Green-top 44 (PPROM). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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