What to Know About Oral Erythromycin

An antibiotic for inflammatory acne and much more

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Oral erythromycin is a prescription antibiotic from the group called macrolide antibiotics, which stop the growth of bacteria. Erythromycin is used to treat both acute (short-term) and chronic (long-term) bacterial infections.

In tablet, capsule, and granule form, oral erythromycin is sold under the brand names:

  • ERY-C
  • Ery-Tab
  • EryPed
  • E-Mycin
  • Erythrocin
  • PCE

Generic erythromycin is available, as well. In addition to oral forms, this drug is sold as a topical gel and liquid, an eye ointment, and an intravenous solution.

A woman holds a white pill in one hand and a glass of water in the other.

Siriporn Kaenseeya / EyeEm / Getty Images


In pill form, erythromycin is approved by the U.S. Food and Drug Adminstration (FDA) to treat:

It's used off-label (without FDA approval) for:

Before Taking

Erythromycin isn't a safe drug for everyone. Before taking it, tell your doctor if you:

  • Have ever had an allergic reaction to erythromycin or similar medications
  • Have been diagnosed with an irregular heartbeat or a heart problem called a prolonged QT interval
  • Have low levels of magnesium or potassium in your blood
  • Have been diagnosed with liver disease
  • Are pregnant, plan to become pregnant, or are breastfeeding
  • Are planning to have surgery, including dental surgery

Talk to your doctor about all medications, supplements, and vitamins that you currently take. While some drugs pose minor interaction risks, others may outright contraindicate use or prompt careful consideration as to whether the pros of treatment outweigh the cons in your case.

These factors may influence your doctor's decision about what antibiotic is right for you.

Precautions and Contraindications

Erythromycin use has contributed to the growing problem of bacterial resistance, which is caused by the overuse of antibiotics. To combat this serious problem, erythromycin should only be prescribed for infections that are known to respond well to this drug.

You shouldn't take erythromycin if you've ever had an allergic reaction to it or any of its ingredients. Your doctor will likely not give you erythromycin if you're currently taking any of these medications:

Pregnancy Warning

If you're pregnant, you shouldn't take a form of erythromycin called erythromycin estolate, which can cause pregnancy-related liver toxicity.

Other Macrolide Antibiotics

Other oral antibiotics in the same class as erythromycin include:


Available dosages for erythromycin include:

  • Oral granules: 5 milliliters (mL), 200 milligrams (mg), 400 mg
  • Oral tablets: 250 mg, 333 mg, 400 mg, 500 mg
  • Oral capsules: 250 mg

Adult dosages for infection vary depending on the infectious agent, with the typical range between 250 mg and 500 mg three or four times per day.

A typical dose for acne is 250 mg or 500 mg twice a day to start, then dropping down to once a day for maintenance.

All listed dosages are according to the drug manufacturer. Check your prescription and talk to your doctor to make sure you are taking the right dose for you.

High Rates of Resistance

Due to high rates of bacterial resistance that have developed, erythromycin is rarely used as an acne treatment.


Pediatric dosages for erythromycin are calculated based on weight.

How to Take and Store

Oral erythrmycin should be taken:

  • By mouth
  • With or without food
  • With a full glass of water
  • Between two and four times per day

Follow your doctor's instructions carefully. Do not crush or chew tablets or capsules, as it may impact the way the drug is released into your system.

You should store erythromycin at room temperature in its original container with the lid tightly closed. It's recommended that you don't store it in the bathroom, where it could be exposed to excess heat and moisture. Keep this and all medications away from children.

Side Effects

As with all medications, you should be aware of possible side effects that may occur with erythromycin.


The most common side effects of erythromycin include:

  • Nausea
  • Stomach pain
  • Vomiting
  • Diarrhea
  • Loss of appetite

Taking this medication with food may help alleviate gastrointestinal side effects. Tell your doctor if these symptoms are persistent or severe.


Less-common side effects may be more serious. Contact your doctor right away or get emergency medical help for any of the following:

  • Rash or hives
  • Itching
  • Wheezing or difficulty breathing or swallowing
  • Yellowed skin or eyes
  • Dark urine
  • Pale stools
  • Unusual fatigue
  • Pain in the upper right part of the stomach
  • Seizures
  • Fast, pounding, or irregular heartbeat
  • Severe diarrhea, possibly bloody, that may occur without fever and stomach cramps

Warnings and Interactions

Erythromycin carries a risk of cardiotoxicity, especially when it comes to lengthening a measure of the heartbeat called the QT interval and a potentially deadly heart rhythm called torsades de pointes. Your doctor should carefully monitor your heart while you're taking this medication. If you're at high risk of these problems, you may need regular testing to monitor levels of:

  • Potassium
  • Magnesium
  • Calcium

Drugs that can have major negative interactions with erythromycin include:

  • Theophylline: brand names are Elixophyllin, Quibron-T, Theo-24, Theochron, Theolair, Uniphyl
  • Verapamil: Calan, Covera HS, Veralan
  • Digoxin: Cardoxin, Digitek, Lanoxicaps, Lanoxin
  • Triazolam: Hacion
  • Tacrolimus: Astagraft XL, Envarsus XR, Prograf, Protopic
  • Colchicine: Colcrys, Gloperba

Common drugs that may have moderate negative interactions with erythromycin include:

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Article Sources
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