Can I take Allopurinol and Co-amoxiclav together?

It is generally considered safe to take allopurinol and co-amoxiclav together, but caution is advised as taking them together increases the risk of developing a rash.

If you notice any new skin rash, redness, or itching, contact your doctor immediately. If you develop a rash along with a fever or swelling of the face, seek urgent medical help.

Why this happens

The exact reason isn't fully understood, but allopurinol seems to make the immune system more sensitive to penicillin-type antibiotics like co-amoxiclav. This makes an allergic-style skin reaction more likely to happen.

How to know if you're having a drug interaction

You may be experiencing an interaction between allopurinol and co-amoxiclav if:

• You develop skin rashes, itching, or hives.

• You experience fever, chills, or flu-like symptoms.

• You notice unusual bruising or bleeding.

• You feel tired, weak, or generally unwell.

• You have swelling of the face, lips, or throat, which may indicate an allergic reaction.

• Symptoms appear shortly after starting or increasing the dose of either medicine.

What you should do

If you have any of the above symptoms, you should:

• Stop taking the medicines and seek advice from your GP or pharmacist immediately.

• Seek urgent medical help if you develop swelling of the face, lips, or throat, or have difficulty breathing.

• Do not restart the medicines until a healthcare professional confirms it is safe.

• Tell your healthcare professional about all other medicines and supplements you are taking.

• Attend any blood tests or monitoring recommended to check for allergic reactions or other side effects.

Important precautions

Severe skin rash

Stop taking allopurinol immediately and seek urgent medical advice if you develop a skin rash, peeling skin, or sores on your lips or mouth. This can be a sign of a rare but life-threatening allergic reaction.

Penicillin allergy

Do not take co-amoxiclav if you have ever had a severe allergic reaction (such as anaphylaxis or a skin rash) to penicillin or any other 'beta-lactam' antibiotic, as this can be fatal.

Liver problems (jaundice)

Seek medical advice if you develop yellowing of the skin or eyes (jaundice) or dark pee (urine). Co-amoxiclav can cause liver inflammation, which may sometimes occur even after you have finished the course.

Food and drink warnings

Alcohol

Alcohol can increase the levels of uric acid in your blood, which makes allopurinol less effective at preventing gout attacks. It is best to limit or avoid alcohol, especially beer and spirits.

Caffeine

High intake of caffeine may interfere with how allopurinol works to lower uric acid. Try to maintain a consistent, moderate intake rather than consuming very large amounts.

Water/fluids

While not a negative interaction, it is vital to drink plenty of fluids (2 to 3 litres a day) while taking allopurinol to help prevent kidney stones.

Food (general)

To reduce the chance of feeling sick or having stomach upset, it is recommended to take co-amoxiclav at the start of a meal.

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.