BMA Concise Guide to Medicine & Drugs


Brand names Erymax, Erythrocin, Erythroped, Primacine, Stiemycin, Tiloryth

Used in the following combined preparations Aknemycin Plus, Isotrexin, Zineryt


Drug group Antibiotic

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic Yes


One of the safest and most widely used antibiotics, erythromycin is effective against many bacteria. It is commonly used as an alternative in people allergic to penicillin and related antibiotics.

Erythromycin is used to treat throat, middle ear, and chest infections (including some rare types of pneumonia such as Legionnaires’ disease). It is also used for sexually transmitted diseases such as chlamydial infections, and in some forms of gastroenteritis. Erythromycin may also be included as part of the treatment for diphtheria and is sometimes given to treat, and reduce the likelihood of infecting others with, pertussis (whooping cough).

When taken by mouth, erythromycin may sometimes cause nausea and vomiting. Other possible adverse effects include rash as well as a rare risk of liver disorders. Oral administration or topical application of the drug is sometimes helpful in treating acne.


Your drug prescription is tailored for you. Do not alter dosage without consulting your doctor.

How taken/used Tablets, capsules, liquid, injection, topical solution.

Frequency and timing of doses Every 6–12 hours before or with meals.

Dosage range 1–4g daily.

Onset of effect 1–4 hours.

Duration of action 6–12 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Take the full course. Even if you feel better, the original infection may still be present and symptoms may recur if treatment is stopped too soon.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


Nausea and vomiting are common adverse effects of erythromycin and most likely with large doses taken by mouth. Diarrhoea is also common. Deafness is a rare adverse effect that may occur with high doses. If you develop impaired hearing, consult your doctor without delay. Symptoms such as rash, itching, skin blisters or ulcers, jaundice, or fever may also occur. If you develop any of these symptoms, stop taking the drug and consult your doctor immediately.


General note Erythromycin interacts with a number of other drugs, particularly:

Mizolastine Erythromycin increases the risk of adverse effects on the heart with this drug.

Warfarin Erythromycin increases the risk of bleeding with warfarin.

Ergotamine Erythromycin increases the risk of side effects with this drug.

Carbamazepine, digoxin, and some immunosuppressants Erythromycin may increase blood levels of these drugs.

Theophylline/aminophylline Erythromycin increases the risk of adverse effects with these drugs.

Simvastatin and other “statins” Erythromycin should not be taken with simvastatin; increased risk of muscle aches and pains with other statins.


Be sure to tell your doctor if:

· You have a long-term liver problem.

· You have had a previous allergic reaction to erythromycin.

· You have porphyria.

· You are taking other medicines.

Pregnancy No evidence of risk to the developing fetus. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk, but at normal doses adverse effects on the baby are unlikely. Discuss with your doctor.

Infants and children Reduced dose necessary.

Over 60 No special problems.

Driving and hazardous work No known problems.

Alcohol No known problems.


Oral courses of longer than 14 days may increase the risk of liver damage.