Sounds like 'eryth-ro-my-cin'

Easy-to-read medicine information about erythromycin – what it is, how to take erythromycin safely and possible side effects.

Type of medicine Also called
  • Antibiotic (to treat infections)
  • Macrolide antibiotic
  • E-Mycin®
  • ERA ®

What is erythromycin?

  • Erythromycin is an antibiotic that is used to treat infections such as chest infections or skin infections.
  • It works by killing or stopping the growth of bacteria (bugs) that cause infection.


  • The usual dose of erythromycin is one tablet (400mg) four times a day.
  • For children, the dose varies with age and weight.
  • Depending on the type of infection your doctor may prescribe a different dose.
  • Your doctor will advise you on how long to take erythromycin for (usually 5 to 10 days).

How to take erythromycin

  • Swallow the tablet with a glass of water.
  • You can take erythromycin with or without food. If you get stomach upset try taking it with food.
  • Take erythromycin at the same times each day. Try to space the doses evenly apart during waking hours, for example: 8am, 1pm, 5pm and 10pm.
  • Keep taking erythromycin until you finish all the tablets. Do not stop taking it, even if you feel better after a few days.
  • If you forget to take erythromycin, take it as soon as you remember.
  • But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Possible side effects

Like all medicines, erythromycin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Nausea (feeling sick) or vomiting
  • Take erythromycin with or after food.
  • Diarrhoea (loose, watery stools)
  • These may go away with time.
  • Tell your doctor if troublesome.
  • Vaginal itching, soreness or discharge (thrush)
  • Tell your doctor or pharmacist.
  • Signs of problems with you liver such as yellowing of the skin or eyes, dark urine, pain in the abdomen. 
  • Tell your doctor immediately or ring HealthLine.


Erythromycin may interact with a few medications or herbal supplements, so check with your doctor or pharmacist before starting erythromycin or before starting any new medicines. Also check with a pharmacist before taking over-the-counter medicines such as theophylline (eg, Neulin)

Learn more

Medsafe Consumer Information Sheet E-Mycin

New Zealand Formulary Patient Information: Erythromycin

Credits: Sandra Ponen, Pharmacist. Reviewed By: Dr J Bycroft. Health Navigator NZ Last reviewed: 12 Jun 2014