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Erythrocin, Erythroped

Erythromycin is an antibiotic. It can be taken by people who are allergic to penicillin.

Space your doses out evenly over the day and complete the full course of this antibiotic, even if you feel your infection has cleared up.

The most common side-effects are feeling sick (nausea) and tummy (abdominal) discomfort. These are usually mild and may be reduced by taking your doses after a meal or snack.

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About erythromycin

Type of medicine

A macrolide antibiotic

Used for

Infections (in adults and children), and for skin problems such as acne and rosacea

Also called

Erythrocin® (as erythromycin stearate), Erythroped® (as erythromycin ethyl succinate)

Available as

Tablets and oral liquid medicine

Erythromycin is prescribed to treat short-term (acute) bacterial infections, such as chest (respiratory) infections, urine infections, skin infections, and mouth infections. It can be taken by adults and children. It works by killing the germs (bacteria) causing the infection. It is also prescribed for some longer-term skin conditions such as acne and rosacea.

Erythromycin is also available as an ingredient in some skin preparations used to treat acne - see the separate medicine leaflet called Erythromycin (with zinc) skin solution for acne for more information about this.

Before taking erythromycin

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking erythromycin it is important that your doctor or pharmacist knows:

  • If you are pregnant or breastfeeding.

  • If you have any problems with your liver or kidneys.

  • If you know you have an unusual heart rhythm or you have any other heart or blood vessel problems.

  • If you have been told you have low levels of potassium or magnesium in your blood.

  • If you have a muscle disorder called myasthenia gravis.

  • If you have a rare inherited blood disorder called porphyria.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to take erythromycin

  • Before you start taking this antibiotic, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about it and a full list of side-effects which you may experience from taking it.

  • Take erythromycin exactly as your doctor tells you to. It is usually prescribed four times daily, although one or two doses daily may be sufficient for some conditions. Your doctor or pharmacist will tell you which dose is right for you (or for your child). Your dose will also be on the label of the pack to remind you. Space the doses out evenly during the day.

  • Swallow erythromycin tablets whole, with a drink of water. Do not chew them. You may take erythromycin before or after food.

  • When erythromycin is prescribed for a child, the dose depends upon the child's weight. Make sure you read the label carefully so that you measure out the correct amount of medicine.

  • Even if you feel your infection has cleared up, keep taking this antibiotic until the course is finished unless your doctor tells you otherwise. This is to prevent the infection from coming back. A course of treatment for a short-term (acute) infection often lasts around 5-14 days. It may last for longer than this if you are taking erythromycin for chronic prostatitis, acne or rosacea - in these cases it is quite normal for your treatment to continue for several weeks or months.

  • If you still feel unwell after finishing your course of treatment, make another appointment to see your doctor for further advice.

  • If you forget to take a dose, take one as soon as you remember. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a forgotten one.

Getting the most from your treatment

  • If you buy any medicines, check with a pharmacist that they are safe to take with erythromycin. If you regularly take an indigestion remedy, make sure your doctor knows about this, as some brands of erythromycin should not be taken at the same time as antacids. Check the label on your pack of erythromycin for more information about this.

  • Some people develop thrush (redness and itchiness in the mouth or vagina) after taking a course of antibiotics. If this happens to you, speak with your doctor or pharmacist for advice.

  • If you are using combined oral hormonal contraception (the 'pill'), additional contraceptive precautions such as condoms are not required during a course of this antibiotic unless you are sick (vomit) or have diarrhoea. If you need further advice about this, speak with your doctor or pharmacist.

  • This antibiotic may stop the oral typhoid vaccine from working. If you are having any vaccinations, make sure the person treating you knows that you are taking this medicine.

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Can erythromycin cause problems?

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. The table below lists some of the most common ones associated with erythromycin. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve over the first few days of taking a new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common erythromycin side-effects

What can I do if I experience this?

Feeling sick (nausea) or being sick (vomiting), tummy (abdominal) discomfort

Stick to simple meals - avoid rich or spicy food. Taking your doses after food may help


Drink plenty of water to replace lost fluids. If the diarrhoea continues or is severe, speak with your doctor

On rare occasions treatment with erythromycin could cause an allergic reaction such as an itchy rash, swelling of the face or mouth and breathing difficulties. If you experience any of these symptoms, stop taking erythromycin and contact your doctor for advice.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

How to store erythromycin

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

  • If you have been given liquid medicine, it will have been made up by the pharmacy and it lasts for a limited number of days only. Check the expiry date on the bottle and do not use it after this date. Store it in the fridge.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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