Erythromycin

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

Erythromycin is a macrolide antibiotic used to treat a range of bacterial infections, including respiratory tract infections, skin and soft-tissue infections, pertussis, and certain sexually transmitted infections. It is a long-standing alternative for patients with penicillin allergy and is also used topically and ophthalmically. Clinically it is notable as a potent inhibitor of the CYP3A4 enzyme, giving it a high potential for drug-drug interactions.

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Publication status

Exploratory record, not a reviewed medical publication.

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This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

Erythromycin is a macrolide antibiotic used to treat a range of bacterial infections, including respiratory tract infections, skin and soft-tissue infections, pertussis, and certain sexually transmitted infections. NutriStack rates the supporting evidence as strong. Common adult dosing is Oral base or stearate 250 mg every 6 hours or 500 mg every 12 hours (typical adult range 1 to 2 g per day, up to 4 g per day in severe infections); ethylsuccinate 400 to 800 mg every 6 to 12 hours., though a prescriber sets the actual dose. With long-term use it can deplete vitamin k. This profile indexes 3 sources.

What it's good for

Community-acquired respiratory tract infections (pharyngitis, bronchitis, atypical pneumonia)
Skin and soft-tissue infections
Pertussis (whooping cough) treatment and prophylaxis
Chlamydial infections and nongonococcal urethritis
Alternative for streptococcal infections in penicillin-allergic patients

What to watch for

Nausea, vomiting, abdominal cramping, and diarrhea (dose-related, motilin-mediated)
Anorexia and epigastric discomfort
QT-interval prolongation and risk of torsades de pointes
Known hypersensitivity to erythromycin or other macrolides^1,2
Concomitant use with terfenadine, astemizole, cisapride, or pimozide (risk of QT prolongation and arrhythmia)

The bottom line

Evidence rating strong. Most-documented uses: community-acquired respiratory tract infections (pharyngitis, bronchitis, atypical pneumonia), skin and soft-tissue infections, pertussis (whooping cough) treatment and prophylaxis. 3 sources indexed (1992–2004), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Erythromycin binds reversibly to the 50S ribosomal subunit of susceptible bacteria, specifically to the 23S ribosomal RNA in the peptidyl transferase region. This binding blocks the exit tunnel for the growing polypeptide chain and inhibits the translocation step of protein synthesis, halting bacterial growth. The effect is generally bacteriostatic but can be bactericidal at high concentrations against highly susceptible organisms. Erythromycin also acts as a motilin receptor agonist in the gastrointestinal tract, which accounts for both its prokinetic effects and its dose-related nausea and cramping. As a strong inhibitor of cytochrome P450 3A4, it can markedly raise plasma concentrations of many co-administered drugs metabolized by that pathway.^1,2

Class

Macrolide antibiotic

Absorption

Best on an empty stomach

Dosing

Dosing & protocol.

Common range

Oral base or stearate 250 mg every 6 hours or 500 mg every 12 hours (typical adult range 1 to 2 g per day, up to 4 g per day in severe infections); ethylsuccinate 400 to 800 mg every 6 to 12 hours.

Recommended form

Oral enteric-coated tablets or delayed-release capsules (base), film-coated stearate tablets, or ethylsuccinate tablets/oral suspension; intravenous lactobionate reserved for severe infection.

Erythromycin base and stearate are acid-labile and are best absorbed on an empty stomach, typically 30 to 60 minutes before or 2 hours after meals; enteric-coated and delayed-release forms protect the drug from gastric acid. The ethylsuccinate salt may be taken without regard to food. Taking with food can reduce gastrointestinal upset for some patients but may lower absorption of the base and stearate.

Depletions

What it depletes.

Nutrients this medication can lower over time, and what to replace.

Vitamin K

Mild

Like most broad-spectrum oral antibiotics, erythromycin can suppress vitamin K-producing colonic bacteria. In patients with already marginal vitamin K intake or stores, this may reduce menaquinone (vitamin K2) availability and impair hepatic synthesis of vitamin K-dependent clotting factors. The effect is generally modest and most clinically relevant in patients who are malnourished or concurrently taking warfarin.

Replace Vitamin KMonitor Prothrombin time / INR (especially in patients on warfarin)Onset Possible within 1 to 2 weeks of therapy, primarily in patients with low dietary vitamin K intake or compromised stores

Full Erythromycin depletion and interaction guide →

Safety

Full safety detail.

Side effects

Nausea, vomiting, abdominal cramping, and diarrhea (dose-related, motilin-mediated)
Anorexia and epigastric discomfort
QT-interval prolongation and risk of torsades de pointes
Reversible hepatotoxicity and cholestatic jaundice (especially estolate)
Reversible dose-related hearing loss with high IV doses or in renal/hepatic impairment
Allergic reactions including rash, urticaria, and anaphylaxis (rare)
Clostridioides difficile-associated diarrhea and superinfection
Infantile hypertrophic pyloric stenosis in neonates exposed in early life

Contraindications

Known hypersensitivity to erythromycin or other macrolides^1,2
Concomitant use with terfenadine, astemizole, cisapride, or pimozide (risk of QT prolongation and arrhythmia)
Concomitant use with ergotamine or dihydroergotamine (ergot toxicity)
Concomitant use with lovastatin or simvastatin (risk of myopathy and rhabdomyolysis)
Pre-existing significant QT prolongation or history of torsades de pointes
Concomitant use with colchicine in patients with renal or hepatic impairment¹

Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Reviews & position papers

1Erythromycin: clinical pharmacology and drug interactionsPeriti P, Mazzei T, Mini E, Novelli A · Clinical Pharmacokinetics · 1992
Erythromycin acts at the 50S ribosomal subunit to block protein synthesis and inhibits hepatic CYP3A4, raising concentrations of many co-administered substrates.

Observational studies

2Oral erythromycin and the risk of sudden death from cardiac causesRay WA, Murray KT, Meredith S, et al. · New England Journal of Medicine · 2004
Current use of oral erythromycin was associated with an increased rate of sudden cardiac death, amplified when combined with CYP3A4 inhibitors.
3Association between erythromycin use in early infancy and pyloric stenosisHonein MA, Paulozzi LJ, Himelright IM, et al. · Lancet · 1999
Exposure to oral erythromycin in the first weeks of life was associated with a substantially increased risk of infantile hypertrophic pyloric stenosis.

FAQ

Common questions.

Quick answers about Erythromycin, drawn from the data on this page.

What is Erythromycin?

What is Erythromycin used for?

Commonly cited benefits of Erythromycin include: Community-acquired respiratory tract infections (pharyngitis, bronchitis, atypical pneumonia); Skin and soft-tissue infections; Pertussis (whooping cough) treatment and prophylaxis; Chlamydial infections and nongonococcal urethritis; Alternative for streptococcal infections in penicillin-allergic patients. NutriStack rates the overall evidence as strong.

What is a typical dose of Erythromycin?

A typical adult dose of Erythromycin is Oral base or stearate 250 mg every 6 hours or 500 mg every 12 hours (typical adult range 1 to 2 g per day, up to 4 g per day in severe infections); ethylsuccinate 400 to 800 mg every 6 to 12 hours.. The commonly recommended form is Oral enteric-coated tablets or delayed-release capsules (base), film-coated stearate tablets, or ethylsuccinate tablets/oral suspension; intravenous lactobionate reserved for severe infection.. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Erythromycin?

Reported side effects include nausea, vomiting, abdominal cramping, and diarrhea (dose-related, motilin-mediated), anorexia and epigastric discomfort, qt-interval prolongation and risk of torsades de pointes, reversible hepatotoxicity and cholestatic jaundice (especially estolate), reversible dose-related hearing loss with high iv doses or in renal/hepatic impairment, allergic reactions including rash, urticaria, and anaphylaxis (rare). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Erythromycin?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

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