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Erythromycin (Erythrocin): Uses, MOA, and Safety

Quick summary Erythromycin is a macrolide antibiotic used for certain bacterial infections. It works by interfering with bacterial protein synthesis. This article summarizes common uses, important warnings, interactions, and safety points to verify with...

Educational content Use this article as a starting point for understanding the topic.
Check with a professional Ask a doctor or pharmacist before changing any medicine.
Safety first Side effects, interactions and risks depend on each person.
Medical disclaimer

This content is for educational purposes only and does not replace medical advice, diagnosis or treatment from a qualified healthcare professional.

Quick summary

Erythromycin is a macrolide antibiotic used for certain bacterial infections. It works by interfering with bacterial protein synthesis. This article summarizes common uses, important warnings, interactions, and safety points to verify with the official product leaflet or a healthcare professional.

Medical disclaimer: This content is for general information only. It does not replace medical advice, diagnosis, or the official prescribing information. Always confirm the exact use, dose, and precautions for your specific product with a doctor, pharmacist, or the FDA medication guide.

What is erythromycin?

Erythromycin (Eritromicina) is a drug used for the treatment of certain infections. It is available in several salt or formulation forms, including erythromycin estolate, ethylsuccinate, gluceptate, lactobionate, phosphate, stearate, sulfate, and thiocyanate.

In the United States, brand names listed for erythromycin include Erythrocin, EryPed, Ery-Tab, and E-Mycin.

How erythromycin works

Erythromycin interferes with bacterial protein synthesis at the 50S ribosomal subunit. This helps stop susceptible bacteria from growing.

Therapeutic uses and indications

The original content lists erythromycin as being used for a range of bacterial infections and related situations. These include:

  • Streptococcal infections, including respiratory, skin, and soft tissue infections, and as an alternative in strep throat.
  • Viridans streptococci: prophylaxis of bacterial endocarditis before certain dental or upper airway procedures in patients with acquired valvular disease or congenital heart disease.
  • Staphylococcus aureus: mild to moderate skin and soft tissue infections.
  • Streptococcus pneumoniae: otitis media, pharyngitis, and mild to moderate pneumonia.
  • Mycoplasma pneumoniae: respiratory infection.
  • Ureaplasma urealyticum: urethritis in adult males.
  • Campylobacter jejuni: enterocolitis and severe or prolonged diarrhoea.
  • Haemophilus influenzae: upper respiratory infection, with sulfonamide.
  • Chlamydia trachomatis: newborn conjunctivitis, infant pneumonia, urogenital infection in pregnancy, and urethral, endocervical, and rectal infection when tetracyclines are contraindicated.
  • Treponema pallidum: primary syphilis in people allergic to penicillin.
  • Corynebacterium diphtheriae: as an antitoxin adjuvant and to prevent carriers.
  • Entamoeba histolytica: intestinal amebiasis.
  • Listeria monocytogenes.
  • Neisseria gonorrhoeae: in women with a history of penicillin sensitivity, and as an alternative to penicillin in PID.
  • Bordetella pertussis: elimination from the nasopharynx and prophylaxis in exposed contacts.
  • It may be effective in legionnaire’s disease.

Because antibiotic choice depends on the infection and local resistance patterns, the exact role of erythromycin should be confirmed by a clinician or the product label.

Dosage information

The original content includes the following dosing ranges. These are presented here for reference only and should not be used as personal treatment instructions.

Use Dose information in source
Adults, oral or IV 1 or 2 g/day in 3-4 doses, can be increased up to 4 g/day
Prevention of viridans streptococcal endocarditis 1 g before surgery and 500 mg every 6 hours, in 8 doses
Primary syphilis 30-40 g fractionated for 10-15 days
Amoebic dysentery 250 mg every 6 hours for 10-14 days
Legionnaire’s disease 1-4 g/day, fractionated, for 14-21 days
Children 30-50 mg/kg/day in 3-4 doses
Children, amoebic dysentery 30-50 mg/kg/day fractionated for 14-21 days
Streptococcal infection with rheumatic heart disease history Minimum 10 days

For any erythromycin product, the exact dose can vary by age, infection, formulation, and medical history. Check the official leaflet or ask a pharmacist to interpret the label.

Contraindications

The source lists the following contraindications:

  • Hypersensitivity to macrolides
  • History of jaundice

Warnings and precautions

The original content highlights the need to monitor liver function because of the risk of dysfunction. It also notes caution during pregnancy and lactation.

Liver failure

Use with caution and monitor liver function.

Drug interactions

Erythromycin has several important interaction concerns in the source material:

  • Plasma concentration increased by terfenadine
  • Avoid association with ergot alkaloids
  • Increased effect of triazolam
  • Monitor with lovastatin
  • Increases levels of theophylline and derivatives and bromocriptine
  • Antagonism with lincomycin and clindamycin
  • Caution with cyclosporine, digoxin, carbamazepine, hexobarbital, phenytoin, antacids, and penicillins
  • May extend prothrombin time with warfarin and other oral anticoagulants

If you take any prescription medicine, over-the-counter product, or supplement, confirm possible interactions with a pharmacist or prescriber before using erythromycin.

Pregnancy and breastfeeding

Pregnancy: The source states that erythromycin crosses the placental barrier, although there is no evidence of action in the fetus. Possible risks should still be considered.

Breastfeeding: The source states that erythromycin passes into breast milk. Although there is no conclusive evidence of an effect on the infant, possible risks should be considered.

Adverse reactions and side effects

The original content lists the following adverse reactions:

  • Abdominal pain
  • Nausea
  • Vomiting
  • Diarrhoea
  • Anorexia
  • Overgrowth of non-susceptible microorganisms
  • Hives
  • Skin rash
  • Anaphylactic phenomena
  • Reversible hearing loss

Any new or severe symptom should be reviewed promptly by a healthcare professional.

What to verify on the official leaflet

If you are reading a product label or medication guide, it is helpful to confirm:

  • The exact formulation and brand name
  • The approved indication for that product
  • The dose and schedule for the specific age group
  • Interaction warnings for your other medicines
  • Any liver-related precautions or monitoring advice

Safety reminder: Antibiotics should be used only when appropriate for a confirmed or strongly suspected bacterial infection. If you have questions about erythromycin, the safest next step is to review the official medication guide or speak with a qualified healthcare professional.

FAQ

▸ What is erythromycin used for?

The source lists erythromycin as being used for certain bacterial infections, including respiratory, skin, soft tissue, and some specific infections such as pertussis, chlamydial infections, and others.

▸ How does erythromycin work?

It interferes with bacterial protein synthesis at the 50S ribosomal subunit.

▸ What are common side effects listed in the source?

The source lists abdominal pain, nausea, vomiting, diarrhoea, anorexia, rash, hives, and reversible hearing loss, among others.

▸ Does erythromycin have important drug interactions?

Yes. The source lists interactions with terfenadine, ergot alkaloids, triazolam, lovastatin, theophylline, bromocriptine, warfarin, and several others.

▸ Should pregnancy or breastfeeding be discussed before use?

Yes. The source notes that erythromycin crosses the placenta and passes into breast milk, so risks should be considered with a clinician.

▸ Where can I check the official FDA information?

The FDA medication guide and product labeling are the best places to confirm the approved use, warnings, and dosing for a specific erythromycin product.

The following resources were included in the original content and may help with ingredient identification and official information:

Editorial note Active Ingredients Online Editorial Team This article is prepared as educational medicine information for general readers. It is written to support understanding of active ingredients, medicine uses, possible side effects, precautions and safety-related questions.
Published: June 15, 2019 Updated: August 17, 2026 Educational content

Medical disclaimer

This content is for educational purposes only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. Always ask a doctor, pharmacist or qualified healthcare professional before starting, stopping or changing any medicine.

Sources and verification

The following sources or official references are listed to support verification of the medicine information discussed in this article.

Final note

Medicine information can change and may vary depending on country, product formulation, patient history and professional guidance. Always check official medicine information and ask a healthcare professional for personal medical questions.

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