Phenoxymethylpenicillin is a type of penicillin.
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.
But 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
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
Carry on taking this medicine until you have completed the course, even if you feel better.
If you stop your treatment early, the infection could come back.
When to take it
Try to space the doses evenly throughout the day. If you take phenoxymethylpenicillin 4 times a day, this could be first thing in the morning, around midday, late afternoon and at bedtime.
If you're taking it twice a day, leave 12 hours between each dose. This could be early morning and early evening, at 8am and 8pm.
It's best not to take phenoxymethylpenicillin at mealtimes. Take it 30 minutes before a meal or at least 2 hours after you have eaten.
How to take it
Swallow phenoxymethylpenicillin tablets whole. Do not chew or break them.
The medicine also comes as a liquid for people who find it difficult to swallow tablets.
If you or your child are taking phenoxymethylpenicillin as a liquid, it'll usually be made up for you by your pharmacist.
The medicine will come with a plastic syringe or spoon to help you measure out the right dose.
If you don't have one, 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 remember your medicines.
What if I take too much?
Accidentally taking an extra dose of phenoxymethylpenicillin is unlikely to harm you or your child.
Speak to your pharmacist or doctor if you're worried, or if you take more than 1 extra dose.
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're 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 sick (nausea)
- being sick (vomiting) or diarrhoea
- stomach pain
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:
- 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
Serious allergic reaction
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
Mild allergic reactions can usually be successfully treated by taking antihistamines.
In rare cases, phenoxymethylpenicillin can cause a serious allergic reaction (anaphylaxis).
Call 999 or go to A&E 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.
These aren't all the side effects of phenoxymethylpenicillin.
For a full list, see the leaflet inside your medicines packet.
You can report any suspected side effect to the UK safety scheme.
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.
- being sick (vomiting) or diarrhoea - drink lots of fluids, such as water or squash, to avoid dehydration. Take small, frequent sips if you're being sick. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea and vomiting without speaking to a pharmacist or doctor.
- stomach pain - 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're in a lot of pain, speak to your pharmacist or doctor.
It's usually safe to take phenoxymethylpenicillin during pregnancy and while breastfeeding.
For safety, tell your doctor if you're trying to get pregnant, already pregnant, or 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:
- a blood thinner called warfarin
- gout medicines called probenecid and sulphinpyrazone
- typhoid vaccine (as capsules)
- other antibiotics
Mixing phenoxymethylpenicillin with herbal remedies and supplements
There are no known problems with taking herbal remedies and supplements with phenoxymethylpenicillin.
For safety, tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.
How does phenoxymethylpenicillin work?
What if I'm allergic to penicillin?
When will I feel better?
What if I don't get better?
How long will I take it for?
Is it safe to take phenoxymethylpenicillin long term?
How does phenoxymethylpenicillin compare with other antibiotics?
Will it affect my contraception?
Will it give me thrush?
Will it affect my fertility?
Can I drive or ride a bike while taking it?
Can I drink alcohol with it?
Is there any food or drink I need to avoid?
Page last reviewed: 06/12/2018
Next review due: 06/12/2021