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First-Generation Macrolide — Penicillin Allergy Alternative / Gastroparesis Prokinetic

Erythromycin

Brand names: Erythrocin, Erythroped, Tiloryth

Erythromycin is a macrolide antibiotic used for respiratory, skin and soft tissue and genital infections, particularly as an alternative in penicillin allergy, and exploited at low doses for its gastrointestinal prokinetic effect.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It binds the 50S bacterial ribosomal subunit and inhibits protein synthesis by blocking translocation; its motilin-receptor agonism underlies its prokinetic action.

Prescribing in practice

  • Erythromycin prolongs the QT interval and inhibits CYP3A, so it can cause serious arrhythmias, especially with other QT-prolonging or interacting drugs such as some statins, which should be reviewed.
  • It frequently causes dose-related gastrointestinal upset including nausea, cramps and diarrhoea.
  • Use in early infancy has been associated with infantile hypertrophic pyloric stenosis.

Monitoring

Routine monitoring is not generally required, but assess for interactions and consider cardiac risk in susceptible patients.

Counselling the patient

  • Take as directed and complete the course even once feeling better.
  • Report palpitations or fainting promptly.
  • Tell your prescriber about all other medicines, as erythromycin interacts with many.

Evidence & guidelines

Erythromycin is a long-established macrolide retained in UK antimicrobial guidance as a penicillin-allergy alternative.

Reference: PHE Antibiotic Guidelines; NICE Pertussis Guidance; MHRA QT Prolongation Guidance; 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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