Phenoxymethylpenicillin is a type of penicillin.

It’s an antibiotic used to treat bacterial infections, including ear, chest, throat and skin infections.

It can also be used to prevent infections if you have sickle cell disease, or if you’ve had chorea (a movement disorder), rheumatic fever or your spleen removed.

The medicine is only available on prescription. It comes as tablets or as a liquid that you drink.

  • You’ll usually take phenoxymethylpenicillin 4 times a day to treat an infection.
  • In most cases you’ll start to feel better in a few days.
  • The most common side effects of phenoxymethylpenicillin are feeling sick and diarrhoea.
  • Some people may have an allergic reaction to antibiotics, especially phenoxymethylpenicillin and other penicillins.
  • You can drink alcohol while taking it.
  • Phenoxymethylpenicillin is also known as penicillin V.

Most adults and children can take phenoxymethylpenicillin, including pregnant and breastfeeding women.

However, phenoxymethylpenicillin isn’t suitable for some people. To make sure this medicine is safe for you, tell your doctor if you have:

  • had an allergic reaction to phenoxymethylpenicillin or any other antibiotics or medicines in the past
  • kidney problems
  • any allergies
  • asthma

The amount of phenoxymethylpenicillin you need depends on your age and how bad the infection is – and whether you’re taking it to treat or prevent an infection.

How much will I take?

For adults and children over 12 years, you’ll usually take:

  • 500mg 4 times a day – for treating infections
  • 500mg twice a day – for preventing infections

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

If you’re taking phenoxymethylpenicillin to prevent infections, your doctor will usually ask you to have blood tests. This is to make sure you are not getting any unexpected side effects.

Common side effects

These common side effects happen in 1 in 10 people. Keep taking the medicine, but tell your doctor or pharmacist if they bother you or don’t go away:

  • feeling or being sick (vomiting)
  • diarrhoea
  • stomach pain

Serious side effects

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

Tell a doctor straight away if you get:

  • redness and peeling of the skin over large areas of your body
  • stomach pain, fever and a lot of watery diarrhoea with blood and mucus in it

Allergic reactions

Around 1 in 10 people have an allergic reaction to phenoxymethylpenicillin.

In most cases, the allergic reaction is mild. Symptoms may include:

  • a raised, itchy skin rash
  • coughing
  • wheezing

Mild allergic reactions can usually be successfully treated by taking antihistamines.

In rare cases, phenoxymethylpenicillin can cause a serious allergic reaction (anaphylaxis).

What to do about:

  • feeling sick – stick to simple meals and don’t eat rich or spicy food while you’re taking this medicine
  • being sick (vomiting) – take small sips of water or other fluids so you don’t become dehydrated
  • diarrhoea – drink plenty of water or other fluids if you have diarrhoea. It may also help to take an oral rehydration drink to prevent dehydration. You can buy sachets of powder from a pharmacy which you mix with water. Don’t take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor
  • stomach pain – try to rest and relax. Putting a hot water bottle on your stomach may help. If you’re in a lot of pain, speak to your pharmacist or doctor

It’s usually safe to take phenoxymethylpenicillin during pregnancy and while breastfeeding.

There are many medicines that don’t mix well with phenoxymethylpenicillin.

Tell your doctor if you’re taking these medicines before you start taking phenoxymethylpenicillin:

Mixing phenoxymethylpenicillin with herbal remedies and supplements

There are no known problems with taking herbal remedies and supplements with phenoxymethylpenicillin.

How does phenoxymethylpenicillin work?