Chlamydial infection
Second line
Treats urogenital chlamydia in pregnancy as an azithromycin alternative. AEMPS considers erythromycin ethylsuccinate safe in gestation.
Macrolide antibiotic
ATC code: J01FA01 (Erythromycin)
Brand names
EryPed, Ery-Tab, Erythrocin
Erythromycin binds the 50S bacterial ribosomal subunit and blocks protein chain elongation. It is bacteriostatic against gram-positive cocci, atypical pathogens (Mycoplasma, Chlamydia, Legionella), and Bordetella pertussis. The drug is a moderate CYP3A4 inhibitor and raises concentrations of statins, cyclosporine, carbamazepine, and warfarin. Erythromycin prolongs the QT interval by blocking the hERG channel; torsades de pointes has been reported, especially with intravenous administration, hypokalaemia, and concomitant QT-prolonging drugs.
Second line
Treats urogenital chlamydia in pregnancy as an azithromycin alternative. AEMPS considers erythromycin ethylsuccinate safe in gestation.
Second line
Macrolide for atypical-pathogen community-acquired pneumonia (Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella). SEIMC prefers azithromycin or clarithromycin for tolerability; erythromycin remains an alternative.
9 pairs found. Sorted from critical to minor.
Mechanism
Erythromycin inhibits CYP3A4 – bromocriptine rises 4-5 fold. Coronary vasospasm and MI reported.
Symptoms
Nausea, vomiting, MI.
Management
Combination contraindicated. Alternative – azithromycin.
Mechanism
Erythromycin inhibits CYP3A4 (disopyramide metabolism) and itself prolongs QT. Dual torsades risk.
Symptoms
QTc above 500 ms, syncope, torsades de pointes within 3-7 days.
Management
Combination contraindicated. Alternative – azithromycin (no CYP3A4 inhibition or QT effect).
Mechanism
Erythromycin is a CYP3A4 inhibitor. Ergotamine rises 5–10 fold, fatal ergotism. Ergomar Section 4.
Symptoms
Digital ischaemia, MI within 1–5 days.
Management
Combination contraindicated.
Mechanism
CYP3A4 inhibition – lovastatin rises 5-fold. Rhabdomyolysis.
Symptoms
Myalgia, weakness, dark urine, rising CK within 5-10 days.
Management
Combination contraindicated.
Mechanism
Erythromycin is a moderate-to-strong CYP3A4 inhibitor. Pimozide concentration rises 3–5 fold, with additive QT prolongation (erythromycin itself is a QT prolonger). Orap Section 4 contraindication.
Symptoms
QT prolongation, syncope, torsades de pointes within 3–10 days.
Management
Combination contraindicated. Alternative: azithromycin or another class. If erythromycin is needed, hold pimozide for the course.
Mechanism
Erythromycin inhibits CYP3A4. Simvastatin is a sensitive substrate; its concentration rises 6-fold. High rate of rhabdomyolysis with fatal cases reported. Zocor Section 4.3 – strict contraindication.
Symptoms
Muscle pain, weakness, dark urine within 7 days. Labs show sharp rise in creatine kinase and creatinine.
Management
Combination contraindicated. Hold simvastatin during erythromycin therapy. Alternative: pravastatin or rosuvastatin – neither is metabolised via CYP3A4.
Mechanism
Erythromycin inhibits CYP3A4. Atorvastatin rises 2-3 fold. recommends dose cap.
Symptoms
Myalgia, weakness, dark urine, rising CK within 5-10 days.
Management
Cap atorvastatin at 20 mg/day. Alternative – azithromycin.
Mechanism
Erythromycin inhibits CYP3A4. Tacrolimus rises 2-3 fold – nephrotoxicity, neurotoxicity.
Symptoms
Rising creatinine, tremor, headache.
Management
Reduce tacrolimus by 50%, check blood level on day 3. Alternative – azithromycin.
Mechanism
Erythromycin inhibits CYP3A4 and CYP1A2. Theophylline rises 35-50%.
Symptoms
Nausea, tremor, tachycardia.
Management
Reduce theophylline by 25-50% with blood level check on days 3-5.
Sources
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FDA Category B. Erythromycin is the AEMPS and SEIMC first-line macrolide in pregnancy due to long-standing experience. The estolate ester is contraindicated because of maternal cholestatic hepatitis risk.
Compatible. Hale L1. Transfers into milk (RID about 2%); infant diarrhoea and candidiasis possible. AEMPS notes a rare association with infant pyloric stenosis after exposure during the first 2 weeks of life.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Erythromycin is evaluated for the following indications with varying evidence strength: Community-acquired pneumonia (evidence tier A), Chlamydial infection (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of Erythromycin (≥ 1 in 100): Nausea, vomiting, diarrhoea, abdominal cramps, Taste disturbance, Elevated transaminases, Ototoxicity with high IV doses. See the Safety section for uncommon and serious reactions.
FDA category B. FDA Category B. Erythromycin is the AEMPS and SEIMC first-line macrolide in pregnancy due to long-standing experience. The estolate ester is contraindicated because of maternal cholestatic hepatitis risk.
Compatible. Hale L1. Transfers into milk (RID about 2%); infant diarrhoea and candidiasis possible. AEMPS notes a rare association with infant pyloric stenosis after exposure during the first 2 weeks of life.
Erythromycin is contraindicated in: Hypersensitivity to macrolides; Severe hepatic impairment; Co-administration with astemizole, terfenadine, cisapride, pimozide, ergotamine, dihydroergotamine, lovastatin, simvastatin (QT prolongation and toxicity); Erythromycin estolate in pregnancy. Full list in the Safety section.