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Macrolide antibiotic

Erythromycin

Brand names: Erythrocin, Erymax

Erythromycin is a macrolide antibacterial used for respiratory, skin and soft-tissue infections and as an alternative in penicillin-allergic patients, and it also has prokinetic gastrointestinal effects.

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 bacterial 50S ribosomal subunit and inhibits protein synthesis; its prokinetic action results from agonism at motilin receptors in the gut.

Prescribing in practice

  • It prolongs the QT interval and is a potent CYP3A4 and P-glycoprotein inhibitor, so it carries a high risk of serious interactions and arrhythmias; review concomitant drugs carefully.
  • Gastrointestinal upset (nausea, vomiting, cramps) is very common and can limit tolerability.
  • Use in early infancy has been associated with infantile hypertrophic pyloric stenosis.

Monitoring

Monitor for gastrointestinal effects, hepatic function with prolonged use, and QT prolongation or interactions in at-risk patients.

Counselling the patient

  • Tell your team about all other medicines, as erythromycin interacts with many drugs.
  • Report palpitations, fainting or an irregular heartbeat.
  • Take as directed and complete the prescribed course.

Evidence & guidelines

The MHRA has highlighted the risk of QT prolongation and drug interactions with macrolides including erythromycin.

Reference: NICE CKS; UKHSA; MHRA Drug Safety Update; 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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