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  1. About erythromycin
  2. Key facts
  3. Who can and cannot take erythromycin
  4. How and when to take it
  5. Side effects
  6. How to cope with side effects
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions

1. About erythromycin

Erythromycin is an antibiotic.

It's widely used to treat chest infections, such as pneumonia, skin problems, such as acne and rosacea, dental abscesses, and sexually transmitted infections.

Erythromycin is used in children, often to treat ear infections or chest infections.

The medicine is available on prescription as tablets, capsules, or a liquid that you drink.

It's also available as a skin solution to treat skin infections like acne. It can be given by injection, but this is usually only done in hospital.

2. Key facts

  • Take erythromycin 2 or 4 times a day as prescribed by your doctor.
  • For most infections, you should feel better within a few days.
  • For skin conditions like acne and rosacea, it may take a couple of months before you see an improvement.
  • The most common side effects of erythromycin are feeling or being sick (nausea or vomiting), stomach cramps and diarrhoea.
  • Drinking alcohol with erythromycin may slightly reduce or delay the medicine's benefits.
  • Erythromcyin is also called by the brand names Erythrocin, Erythrolar, Erymax, Tiloryth, Rommix, Erythroped A and Erythroped.

3. Who can and cannot take erythromycin

Erythromycin can be taken by adults, including pregnant and breastfeeding women.

Erythromycin can be taken by children.

Erythromycin isn't suitable for certain people. To make sure erythromycin is safe for you, tell your doctor if you have:

  • had an allergic reaction to erythromycin or other antibiotics in the past
  • a rare, inherited blood disorder called porphyria
  • liver or kidney problems
  • had diarrhoea when you've taken antibiotics before
  • fast, pounding or irregular heartbeats
  • a sexually transmitted infection called syphilis and you're pregnant - erythromycin alone may not be able to prevent your baby getting the infection
  • a muscle-weakening illness called myasthenia gravis - erythromycin can make your symptoms worse
  • low potassium or magnesium levels, or have been diagnosed with this in the past

4. How and when to take it

The usual dose of erythromycin is 250mg to 1,000mg taken 4 times a day. Sometimes it's taken twice a day. The dose may be lower for children.

Try to space the doses evenly throughout the day - for example, first thing in the morning, at about midday, late in the afternoon and at bedtime.

Generally, it's better to take erythromycin with food so it doesn't upset your stomach.


Carry on taking this medicine until the course is completed, even if you feel better. If you stop your treatment early, your infection could come back.

How to take it

Swallow erythromycin tablets or capsules whole with a drink of water. Do not chew or break them.

There's a liquid erythromycin for children and people who find it difficult to swallow tablets.

If you or your child are taking erythromycin as a liquid, it'll usually be made up for you by your pharmacist. The medicine will come with a syringe or spoon to help you take the right amount. If you don't have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give the right amount.

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it's nearly time for your next dose. In this case, just leave out the missed dose and take your next dose as normal.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Try to take the correct number of doses each day, leaving at least 4 hours between doses.

Taking an extra dose of erythromycin by accident is unlikely to harm you or your child. It may, however, increase the chance of temporary side effects, such as hearing loss, feeling or being sick and diarrhoea.

Talk to your pharmacist or doctor if you're worried, or if you or your child accidentally take more than 1 extra dose.

5. Side effects

Like all medicines, erythromycin can cause side effects, although not everyone gets them.

Information for parents and carers

If your baby is vomiting or very irritable after feeding, stop giving them erythromycin and contact your doctor, midwife or health visitor for advice.

Common side effects

These common side effects of erythromycin happen in more than 1 in 100 people.

Keep taking the medicine, but talk to your doctor or pharmacist if these side effects bother you or don't go away:

  • feeling sick (nausea)
  • being sick (vomiting) and diarrhoea
  • stomach cramps
  • loss of appetite
  • bloating and indigestion

Serious side effects

Serious side effects are rare and happen in less than 1 in 1,000 people.

Call a doctor straight away if you get:

  • chest pains or your heart is beating abnormally
  • skin rash
  • severe stomach pain - this can be a sign of pancreas problems
  • yellowing of the skin or the whites of the eyes, or pale poo with dark pee - these can be signs of liver or gallbladder problems
  • seizures
  • hallucinations (seeing or hearing things that aren't there)
  • ringing in the ears, temporary hearing loss, or feeling unsteady on your feet
  • a temperature of 38C and above

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to erythromycin.

Immediate action required: Call 999 or go to A&E now if:
  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

6. How to cope with side effects

What to do about:

  • feeling sick (nausea) - stick to simple meals and do not eat rich or spicy food while you're taking this medicine. It might help to take your erythromycin with a meal or snack.
  • being sick (vomiting) and diarrhoea - drink lots of fluids, such as water or squash and take small, frequent sips if you feel sick to avoid dehydration. Signs of dehydration include peeing less than usual or having strong-smelling pee. Do not take any other medicines without speaking to a pharmacist or doctor.
  • stomach cramps - try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you are in a lot of pain, speak to your pharmacist or doctor.
  • loss of appetite - eat when you would usually expect to be hungry. If it helps, eat smaller meals more often than usual. Snack when you're hungry.
  • bloating and indigestion - try not to eat foods that cause wind (like lentils, peas, beans and onions). Eat smaller meals, eat and drink slowly, and exercise regularly. Pharmacy medicines like simethicone can also help.

7. Pregnancy and breastfeeding

It's usually safe to take erythromycin during pregnancy and while breastfeeding.

For more information about how erythromycin can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.


For safety, tell your doctor if you're trying to get pregnant, are already pregnant or if you're breastfeeding.

8. Cautions with other medicines

There are some medicines that don't mix well with erythromycin.

Tell your doctor if you're taking these medicines before you start erythromycin:

  • antihistamine medicines, such as astemizole, terfenadine or mizolastine
  • an anti-sickness medicine called domperidone
  • medicines for mental health problems called pimozide and amisulpride
  • migraine medicines called ergotamine and dihrydroergotamine
  • a cholesterol-lowering medicine called simvastatin
  • a bladder weakness medicine called tolterodine
  • rivaroxaban (a blood thinner) - erythromycin can increase the risk of bleeding

Mixing erythromycin with herbal remedies and supplements

There are no known problems with taking herbal remedies or supplements alongside erythromycin.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions

How does erythromycin work?

Erythromycin is from a group of medicines called macrolide antibiotics. Macrolide antibiotics work by killing the bacteria causing the infection.

When will I feel better?

For most infections, you should feel better within a few days.

For skin problems such as acne and rosacea, expect to take the medicine for at least 2 months before you see much improvement.

It's very important that you keep taking erythromycin until your course is finished. Do this even if you feel better. It will help to stop the infection coming back.

Can I drink alcohol with it?

There's no specific warning to stop drinking alcohol while taking erythromycin, but there's some evidence that alcohol may slow down or delay the medicine working. You might want to stop drinking alcohol or limit how much you drink while you're taking erythromycin.

Will it give me thrush?

Some people get a fungal infection called thrush after taking a course of antibiotics like erythromycin. It happens because antibiotics kill the normal harmless bacteria that help to protect you against thrush.

Ask your pharmacist or doctor for advice if this happens to you.

Will it stop my contraception working?

Erythromycin doesn't stop contraceptive pills working, including the combined pill and emergency contraception.

However, if erythromycin makes you sick or have severe diarrhoea (6 to 8 watery poos in 24 hours) for more than 24 hours, your contraceptive pill may not protect you from pregnancy. Look on the pill packet to find out what to do.

Read more about what to do if you're on the pill and you're sick or have diarrhoea.

Will it reduce my fertility?

There's no firm evidence to suggest that taking erythromycin will reduce fertility in women.

However, there's been research suggesting that erythromycin may reduce male fertility by reducing and slowing down sperm. The evidence is weak, though, and this link isn't proven. Talk to your doctor if you're concerned.

What if I don't get better?

Tell your doctor if you don't start feeling better after taking erythromycin for 3 days. Also tell them if, at any time, you start to feel worse.

If you're taking erythromycin for a skin infection, it may take several weeks to see an improvement.

Is there any food or drink I need to avoid?

Do not eat grapefruit or drink grapefruit juice while you're taking erythromycin.

Grapefruit can increase the amount of erythromycin in your body and mean you're more likely to have side effects.