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Medicine guide

Phenoxymethylpenicillin

About this information

This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.

Phenoxymethylpenicillin

What it's for

Phenoxymethylpenicillin

How it's used (previously Dosage and administration)

Phenoxymethylpenicillin

Side effects

Phenoxymethylpenicillin

Who it's for

Phenoxymethylpenicillin

Interactions

Phenoxymethylpenicillin is an antibiotic used to treat bacterial infections and help prevent some infections.

Phenoxymethylpenicillin comes as tablets and a liquid that you swallow. Follow the instructions that come with your medicine.

Common side effects of phenoxymethylpenicillin include feeling sick (nausea), diarrhoea and being sick (vomiting). Serious side effects are rare.

Most adults and children can take phenoxymethylpenicillin, but it's not suitable for everyone. Always check before taking it.

Taking phenoxymethylpenicillin with other medicines, such as some antibiotics and anticoagulants, can cause problems. Always check before taking it.

What phenoxymethylpenicillin is for

Phenoxymethylpenicillin is mainly used to treat bacterial infections, including some:

  • ear infections
  • throat infections
  • chest infections
  • skin infections

It's also used to help prevent some infections – for example, in people who:

  • have sickle cell disease
  • have had their spleen removed

How to take phenoxymethylpenicillin

Phenoxymethylpenicillin comes as tablets and as a liquid that you swallow.

How much you need to take and for how long depends on why you're taking it. Most people need to take it 2 to 4 times a day for a few days or weeks to treat an infection.

If you're taking it to help prevent infections you may take it for longer, sometimes for life.

When taking phenoxymethylpenicillin:

  • swallow tablets whole, with a glass of water
  • use the syringe or spoon that comes with the liquid medicine to help you measure the right dose
  • try to space your doses evenly throughout the day
  • take it at least 30 minutes before eating food or at least 2 to 3 hours after food

Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or have any problems taking it.

Important

It's important to keep taking your medicine for as long as has been prescribed, even if you start to feel better.

If you miss a dose of phenoxymethylpenicillin

If you forget to take a dose, take it as soon as you remember, unless it's nearly time for your next dose.

If it's nearly time for your next dose, skip the missed dose and take your next dose at the usual time.

Do not take 2 doses at the same time. Do not take an extra dose to make up for a missed dose.

If you take too much phenoxymethylpenicillin

Taking an extra dose of phenoxymethylpenicillin is unlikely to cause problems, but it's important to get medical advice if you take too much because it can sometimes be dangerous.

Speak to a pharmacist as soon as possible if:

  • you've taken more than your prescribed dose of phenoxymethylpenicillin

If you're unable to speak to a pharmacist, or you took too much on purpose, call NHS 111 for advice.

Find a pharmacy

Information

If you're told to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.

Bring the phenoxymethylpenicillin packet or leaflet inside it, any remaining medicine, and any other medicines you take.

Side effects of phenoxymethylpenicillin

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

Common side effects

Common side effects of phenoxymethylpenicillin include:

  • feeling sick (nausea) and being sick (vomiting)
  • diarrhoea
  • stomach pain or cramps
  • loss of appetite
  • farting

Phenoxymethylpenicillin will not usually affect your ability to drive, ride a bike or use machinery.

Speak to a pharmacist or doctor if:

  • you have any side effects that bother you or do not go away

They may be able to give you advice about how you can reduce the side effects. Keep taking your medicine unless you're advised to stop.

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Serious side effects

Phenoxymethylpenicillin can sometimes cause serious side effects, although most of them are rare.

Possible serious side effects of phenoxymethylpenicillin include:

  • an allergic reaction (anaphylaxis) – causing symptoms such as a swollen mouth, throat or tongue, difficulty breathing or severe dizziness
  • angioedema – causing swelling in areas such as your lips, tongue and face (you have a higher chance of getting angioedema if you have black skin)
  • an itchy or painful rash, blisters or sores in your mouth, eyes or genitals – this could be a sign of Stevens-Johnson syndrome
  • severe diarrhoea containing blood or mucus

Call 999 if:

  • you're taking phenoxymethylpenicillin and think you might be having anaphylaxis, angioedema or a severe skin rash (Stevens-Johnson syndrome)

If you think you are having any other side effect, call NHS 111.

Who can and cannot take phenoxymethylpenicillin

Most adults and children can take phenoxymethylpenicillin, but it's not suitable for some people.

For example, it may not be suitable if:

  • you've ever had an allergic reaction or serious side effect from phenoxymethylpenicillin, penicillin or another antibiotic
  • you have a condition that affects your stomach and regularly causes you to be sick (vomit)
  • you have kidney problems
  • you have allergies or asthma

Before taking phenoxymethylpenicillin, tell your doctor if you have any medical conditions.

Breastfeeding and phenoxymethylpenicillin

You can usually take phenoxymethylpenicillin while breastfeeding, but check with a doctor or pharmacist first.

It's rare for breastfed babies to get any side effects from medicine you are taking, but speak to a healthcare professional or call NHS 111 if you have any concerns about your baby.

Pregnancy and phenoxymethylpenicillin

You can usually take phenoxymethylpenicillin if you're pregnant, but it's best to check with a pharmacist or doctor first.

Taking phenoxymethylpenicillin with other medicines, food and drink

There are some medicines, remedies and supplements that may not mix well with phenoxymethylpenicillin.

This includes:

  • methotrexate, used to treat immune conditions such as rheumatoid arthritis, psoriasis and Crohn's disease
  • some antibiotics, such as tetracyclines, erythromycin and neomycin
  • some anticoagulants, such as warfarin
  • medicines used to treat gout, such as probenecid

Before taking phenoxymethylpenicillin, tell your doctor or pharmacist if you're taking any medicines, herbal remedies, vitamins or supplements.

Food, drink and alcohol with phenoxymethylpenicillin

You can eat and drink normally while taking phenoxymethylpenicillin.

Try to limit how much alcohol you drink while taking it as alcohol can increase the risk of side effects.

It's best to take phenoxymethylpenicillin 30 minutes before eating food or at least 2 to 3 hours after food.

Content supplied by the NHS website

Content supplied by the NHS website, refreshed 16 September 2026. View the original NHS article ↗

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