Erythromycin

Pronunciation: eh-RITH-roh-MY-sin.

Generic name
erythromycin
Brand names
E-Mycin, Ery-Tab, Erythrocin, ERYC, Erythroped
Drug class
Macrolide antibiotic
Form
Tablet, delayed-release/gastro-resistant tablet, capsule, oral suspension, or powder for intravenous infusion
Route
Oral or intravenous
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: ERYC / Mayne Pharma Erythromycin (6) · Full directory

What erythromycin is and how it works

Erythromycin is a prescription-only macrolide antibiotic used to treat infections caused by bacteria that are sensitive to it. (1)

Take erythromycin exactly as your prescriber directs, for the full course even if you feel better. Your exact dose, formulation, and length of treatment are individually decided based on the infection being treated -- there is no single standard dose for everyone.

Mechanism of action: how erythromycin works

Erythromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding reversibly to the 50S ribosomal subunit of susceptible organisms, blocking translocation of peptidyl tRNA. (1)

What erythromycin is used for

Bacterial infections

Used to treat infections caused by susceptible bacteria, including upper and lower respiratory tract infections, skin and soft-tissue infections, Chlamydia trachomatis infections, pertussis (whooping cough), diphtheria (as an adjunct), syphilis in penicillin-allergic patients, and Legionnaires' disease. Also used to help prevent recurrent rheumatic fever in patients allergic to penicillin. (1)

Before taking erythromycin

Do not take / not appropriate for

  • Do not take erythromycin if you have had a serious allergic reaction to it. (all countries) (1)
  • Do not take erythromycin together with terfenadine, astemizole, pimozide, or cisapride -- this combination can cause life-threatening heart rhythm problems. (all countries) (1)

Tell your clinician about

  • Any personal or family history of an irregular heartbeat, a prolonged QT interval, or other heart rhythm problems.
  • Any low potassium or magnesium levels, or medicines that can lower them (such as some diuretics).
  • Any liver problems, or a past reaction to erythromycin affecting the liver.
  • All other medicines and supplements you take -- erythromycin affects how many other drugs are broken down by the body, including statins (lovastatin, simvastatin), some benzodiazepines, ciclosporin, and tacrolimus.
  • Pregnancy, plans for pregnancy, or breastfeeding.
  • If the medicine is for a young infant, especially in the first weeks of life -- discuss the small increased risk of a stomach-narrowing condition (pyloric stenosis) with the prescriber.
(1)

How to take erythromycin

  • Take at evenly spaced times as directed, usually on an empty stomach (at least 30 minutes, ideally 2 hours, before a meal) for the best absorption, unless your specific product's instructions say otherwise.
  • Complete the full course your prescriber has set, even if symptoms improve early -- stopping early can allow the infection to return or contribute to antibiotic resistance.
  • Do not take a different salt or brand of erythromycin than the one prescribed without checking with your prescriber or pharmacist, since doses are not directly interchangeable between salts.
(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7)

Missed dose

Take the missed dose as soon as you remember, unless it is almost time for the next dose -- in that case, skip the missed dose and continue your regular schedule. Do not take a double dose to make up for a missed one. Ask your pharmacist or prescriber if unsure.

Overdose

Seek urgent medical attention if too much erythromycin has been taken, or if severe abdominal pain, vomiting, diarrhoea, or signs of an irregular heartbeat develop. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Nausea, vomiting, abdominal pain or cramping, and diarrhoea are commonly reported and are often dose-related.

What to notice: Nausea, vomiting, abdominal pain or cramping, and diarrhoea are commonly reported and are often dose-related.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Loss of appetite.

What to notice: Loss of appetite.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Skin rash or allergic-type reactions.

What to notice: Skin rash or allergic-type reactions.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of an abnormal heart rhythm (QT prolongation / torsades de pointes) — emergency

Symptoms: Fainting, a fast or irregular heartbeat, or palpitations.

Action: Seek emergency medical help immediately. This risk is higher with existing heart rhythm problems, low potassium or magnesium levels, or when combined with certain other medicines. (1)

Signs of a liver problem (cholestatic hepatitis) — high caution

Symptoms: Yellowing of the skin or eyes (jaundice), dark urine, itching, nausea, fever, or abdominal pain, typically appearing after 10-14 days of treatment.

Action: Contact your prescriber promptly. This risk has historically been most strongly linked to the estolate salt of erythromycin. (1)

Severe or persistent diarrhoea during or after treatment (possible C. difficile-associated colitis) — high caution

Symptoms: Watery or bloody diarrhoea, abdominal cramping, or fever, which can appear during treatment or up to several weeks after stopping.

Action: Contact your prescriber promptly; this needs medical evaluation and should not be treated with anti-diarrhoeal medicines on your own. (1)

Feeding difficulty or vomiting in a young infant taking erythromycin (possible pyloric stenosis) — high caution

Symptoms: Forceful (projectile) vomiting, persistent feeding difficulty, or poor weight gain in an infant, especially in the first weeks of life.

Action: Contact the infant's clinician promptly for evaluation. A small increased risk of this stomach-narrowing condition has been reported with erythromycin exposure in young infants. (1) (2)

Signs of a serious allergic reaction — emergency

Symptoms: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread rash or hives.

Action: Seek emergency medical help immediately. (1)

Interactions

  • Combining erythromycin with terfenadine, astemizole, pimozide, or cisapride is contraindicated because of a risk of life-threatening heart rhythm problems. (1)
  • Erythromycin can raise blood levels of statins such as lovastatin and simvastatin, increasing the risk of muscle breakdown (rhabdomyolysis); a prescriber may need to adjust or pause statin therapy. (1)
  • Can increase levels of certain benzodiazepines, ciclosporin, tacrolimus, and other medicines broken down by the same liver pathway (CYP3A4) -- tell your prescriber about all medicines you take. (1)
  • Other medicines that prolong the QT interval, or that lower potassium/magnesium (such as some diuretics), can add to the heart-rhythm risk. (1) (4)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Animal studies have not shown clear risk, but there are no well-controlled human trials. Discuss the benefits and risks with your prescriber. Note that erythromycin base/stearate may not reliably reach the fetus at levels adequate to prevent congenital syphilis, so an alternative treatment approach may be needed in that specific situation. (1) (2) (3) (4) (5) (6) (7)

Breastfeeding

Erythromycin passes into breast milk. Discuss the benefits and risks with your prescriber. (1) (2) (3) (4) (5) (6) (7)

Children

Used in children with weight-based dosing for susceptible infections; a small increased risk of pyloric stenosis has been reported with systemic exposure in the first weeks of life. (1) (2) (3) (4) (5) (6) (7)

Elderly

No specific dose adjustment based on age alone is described in the source reviewed, but hearing changes and drug interactions may warrant closer monitoring. (1) (2) (3) (4) (5) (6) (7)

Hepatic_impairment

Use with caution -- erythromycin is processed by the liver and has been linked to liver injury, particularly with prolonged therapy or the estolate salt; tell your prescriber about any liver problems. (1) (2) (3) (4) (5) (6) (7)

Renal_impairment

Reversible hearing loss has been reported more often with high doses or existing kidney problems; tell your prescriber about any kidney issues. (1) (2) (3) (4) (5) (6) (7)

Monitoring

Before starting

  • Review of other medicines for interaction risk, especially QT-prolonging drugs and CYP3A4-metabolised medicines
  • Baseline liver function if there is a history of liver problems
  • ECG/electrolyte review if there is a personal history of heart rhythm problems

During treatment

  • Watch for gastrointestinal symptoms, which are common and often dose-related.
  • Watch for signs of liver problems, especially with treatment courses longer than about 2 weeks.
  • Watch for signs of an abnormal heart rhythm, especially if other risk factors are present.
  • In young infants, watch for feeding difficulty or vomiting.
(1)

Storage

Store below 30°C (86°F) in a tightly closed container, protected from light, unless your specific product's label states otherwise.

Study the drug class: Macrolides

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information; verify against the current full label and the specific salt/formulation before prescribing.

United States

Indication: Susceptible bacterial infections

Dose summary: Individualised by infection and severity. Adults: commonly 250 mg PO four times daily or 500 mg every 12 hours, up to 4 g/day for severe infections. Children: commonly 30-50 mg/kg/day in divided doses, up to 4 g/day. Best absorbed on an empty stomach. Streptococcal infections require a minimum 10-day course.

Renal context: Not established in the source reviewed for this dossier; reversible ototoxicity has been reported more often with renal impairment or high doses -- monitor accordingly. (1)

Mechanism of action

Hepatic guidance

Hepatic dysfunction, including hepatocellular and/or cholestatic hepatitis with or without jaundice, has been reported, historically most strongly with the estolate salt; risk factors include pregnancy, prolonged therapy (>14 days), prior erythromycin-associated hepatotoxicity, and pre-existing liver disease.

Overdose note

Overdose management is supportive; monitor for gastrointestinal symptoms and cardiac arrhythmia. No specific antidote is described in the source reviewed. (1)

Frequently asked questions

Is erythromycin available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, it is approved and available in all of these regions, under various brand names and salts. (1) (3) (4) (5) (6) (7)

Can erythromycin affect my heart rhythm?

Yes. Erythromycin can prolong the QT interval and has been linked to serious heart rhythm problems, including torsades de pointes, especially in people with existing heart rhythm issues, low potassium or magnesium, or when combined with certain other medicines. Tell your prescriber about any heart rhythm history before starting. (1) (4)

Why does erythromycin affect other medicines I take?

Erythromycin blocks a liver enzyme (CYP3A4) that many other drugs rely on to be broken down, which can raise their blood levels significantly. This is why it is contraindicated with certain medicines and needs caution with others, including some statins, benzodiazepines, ciclosporin, and tacrolimus. (1)

What is the mechanism of action of erythromycin?

Erythromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding reversibly to the 50S ribosomal subunit of susceptible organisms, blocking translocation of peptidyl tRNA. (1)

What is the generic name of Erythromycin?

The generic name is erythromycin. It is sold under brand names including E-Mycin, Ery-Tab, Erythrocin, ERYC, Erythroped. (1)

What class of drug is erythromycin?

Erythromycin is classed as: Macrolide antibiotic. (1)

References

  1. ERYTHROMYCIN tablet, film coated -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-29 · source 1
  2. Very early exposure to erythromycin and infantile hypertrophic pyloric stenosis; Systemic but not topical erythromycin use increases IHPS riskPeer-reviewed literature (PubMed/JAMA Pediatrics/AAP Grand Rounds) corroborating the FDA label's IHPS warning · United States · accessed 2026-07-29 · source 2
  3. Erythromycin Tablets BP 250mg -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-29 · source 3
  4. Erythromycin: CMDh scientific conclusions and grounds for variation of the marketing authorisation(s) -- PSUSA/00001257/201903European Medicines Agency (EMA) / CMDh -- Periodic Safety Update Single Assessment (PSUSA) referral outcome · European Union · accessed 2026-07-29 · source 4
  5. ERYC (erythromycin) Product MonographHealth Canada product monograph · Canada · accessed 2026-07-29 · source 5
  6. ERYC erythromycin 250mg capsule -- ARTG registrationTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 6
  7. E-Mycin / ERA Filmtabs / Erythrocin IV New Zealand Data SheetsMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-29 · source 7

Brand names by country

Single-ingredient erythromycin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Ery20 mg/mL · bryant ranch prepack
  • ERY-TAB333 mg, 500 mg, 250 mg · arbor pharmaceuticals, inc.

United Kingdom

  • Erythromycin Tablets BP / Erythroped (3)MHRA licensed emc smpc confirmed · 250 mg tablet, 125 mg/5 mL and 250 mg/5 mL suspension · Strides Pharma UK Ltd / Pinewood Healthcare / others

Canada

  • EES-200
  • ERYC DELAYED-RELEASE
  • ERYTHRO-S
  • ERYTHROCIN I.V.
  • ERYBID
  • ERYTHRO-ES
  • ERYTHRO-BASE
  • ONGUENT OPHTALMIQUE D'ERYTHROMYCINE
  • PCE
  • NOVO-RYTHRO ESTOLATE

Australia

  • ERYC / Mayne Pharma Erythromycin (6)TGA ARTG registered confirmed · 250 mg capsule · Mayne Pharma / Aspen

New Zealand

  • E-Mycin / ERA Filmtabs / Erythrocin IV (7)Medsafe approved confirmed · 200 mg/5 mL and 400 mg/5 mL suspension, 400 mg tablet, 250 mg and 500 mg tablet (stearate), 1 g injection (lactobionate) · Multiple
View brands in additional countries.

European Union

Erythromycin (nationally authorised across EU member states; no single centralised EPAR) (4)

This page provides general reference information about erythromycin and is not a substitute for advice from the prescriber managing your treatment. All dosing and treatment decisions should be made with your prescriber.

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