Experiences with
Allopurinol

Allopurinol is a medicine used to lower levels of uric acid in your blood.

If you produce too much uric acid or your kidneys do not filter enough out, it can build up and cause tiny, sharp crystals. These crystals can form around your joints, which cause the swollen and painful symptoms of gout. Crystals can also collect inside the kidneys and damage them.

It may also be prescribed if you're having some types of cancer treatment. Some treatments can cause a build-up of uric acid.

Allopurinol comes as tablets and is only available on prescription.

Who can take allopurinol

Allopurinol can be taken by adults and sometimes children.

Who may not be able to take allopurinol

Allopurinol is not suitable for some people. To make sure it's safe for you, tell your pharmacist or doctor before taking it if you:

have ever had an allergic reaction to allopurinol or any other medicine
are of Han Chinese, Thai or Korean origin
have problems with your liver or kidneys
currently have an attack of gout
have thyroid problems

Dosage

Allopurinol comes as 100mg to 300mg tablets that you take every day. Follow your doctor's advice on how many tablets to take, and how many times a day.

You'll usually start on a low dose of allopurinol, but if your uric acid level does not come down far enough, your doctor may increase your dose (up to 900mg daily in severe cases).

If you have kidney or liver disease, your doctor may prescribe a lower dose and will monitor you more closely.

You'll have regular blood tests to monitor your uric acid levels.

How to take it

Swallow your allopurinol tablet with water, ideally after food.

You'll usually take it once a day, but if you're on a high dose, your doctor may advise you to split the dose and take it twice a day.

If your doctor has recommended you take allopurinol with lots of fluid, try to drink 2 to 3 litres of fluids every day.

You can take allopurinol at any time of the day. However, try to take your doses at the same time of day each day.

How long to take it for

If allopurinol works for you, you may need to take it for the rest of your life to treat gout and kidney stones.

If you stop allopurinol treatment suddenly, there is a high risk that gout may get worse or you'll get serious side effects.

Only stop taking allopurinol if a doctor tells you to. A doctor will help you to reduce your dose slowly so you do not get serious side effects.

If you forget to take it

If you take allopurinol once a day, take the missed dose as soon as you remember, unless it's almost time to take the next dose. In this case, skip the missed dose and take your next dose at the usual time.

If you take allopurinol twice or more a day and do not remember until your next dose is due, skip the missed dose and take your next dose at the usual time.

Never take 2 doses to make up for a missed dose.

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

If you take too much

You take more than your prescribed dose of allopurinol and you have any of these symptoms:

feeling or being sick (nausea or vomiting)
diarrhoea
feeling dizzy or tired
headaches
stomach pain

Go to 111.nhs.uk or call 111 . If you need advice for a child under the age of 5, call 111.

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the allopurinol packet or leaflet inside it, plus any remaining medicine, with you.

Common side effects

There are things you can do to cope with these common side effects of allopurinol:

It's unusual to have serious side effects after taking allopurinol. Tell a doctor or contact 111 straight away if:

the whites of your eyes or your skin turn yellow, although this is less obvious on black or brown skin – these can be signs of a liver problem
you get a high temperature, sore throat and swollen glands or feel generally unwell – this could mean there are problems with your white blood cells
you have bruising for no obvious reason or bleeding gums (which takes a long time to stop) when brushing your teeth
you are unusually thirsty, going to the toilet to pee a lot, unusually tired, losing weight without trying, or have blurred vision – these could be signs of diabetes

Skin rashes

Stevens-Johnson syndrome is a rare side effect of allopurinol. It causes flu-like symptoms, followed by a red or purple rash that spreads and forms blisters. The affected skin eventually dies and peels off.

It's more likely to happen in the first 8 weeks of taking allopurinol, or when the dose is increased too quickly. It can also happen if allopurinol is stopped suddenly for a few days and then restarted at the same dose as before. It's better to reduce the dose and then increase it slowly.

Stevens-Johnson syndrome is more common in:

children
people who developed a rash with an epilepsy medicine in the past
people who are allergic to an antibiotic called trimethoprim
people also taking a medicine called sodium valproate

To help prevent the chance of you getting a rash that could be confused with Stevens-Johnson syndrome, it's best not to try new medicines or food during the first 3 months of treatment with allopurinol.

It's also best to not start taking allopurinol within 2 weeks of a viral infection, vaccination, or rash caused by something else.

you get a skin rash with flushing, blisters or ulcers – these can be signs of Stevens-Johnson syndrome

Find your nearest A&E

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

These are not all the side effects of allopurinol. For a full list, see the leaflet inside your medicines packet.

Allopurinol and pregnancy

Allopurinol is not usually recommended during pregnancy. There is not enough evidence to say that it's safe.

Talk to a doctor if you're thinking about trying for a baby. There may be other medicines that are more suitable for you to take during pregnancy.

Allopurinol and breastfeeding

If your doctor or health visitor says your baby is healthy, you can take allopurinol while you're breastfeeding.

There is not much information about using allopurinol while breastfeeding, but it is likely that allopurinol passes into breast milk in small amounts

If you notice that your baby is not feeding as well as usual, is being sick (vomiting), has diarrhoea or a rash, or if you have any other concerns about your baby, then talk to your doctor, pharmacist, midwife or health visitor.

Allopurinol and fertility

There is no evidence to suggest that taking allopurinol reduces fertility in either men or women. However, talk to a doctor if you want to try for a baby while taking allopurinol.

Cautions with other medicines

Some medicines and allopurinol can affect each other and increase the chances of you having side effects.

Tell a doctor or pharmacist if you're taking any of these medicines before you start taking allopurinol:

aspirin or medicines used to help prevent blood clots (anticoagulants), such as warfarin
any antibiotics
medicines used to reduce your immune response (for arthritis or after you've had an organ transplant)
tablets that make you pee more (diuretics) such as furosemide or ACE inhibitors to treat high blood pressure (hypertension) such as enalapril or ramipril

If you take aluminium hydroxide (found in some antacids such as Maalox and Mucogel), leave a 3-hour gap between the aluminium hydroxide and your allopurinol dose.

Taking allopurinol with painkillers

You can take allopurinol with paracetamol and anti-inflammatory medicines such as ibuprofen, naproxen, or indomethacin.

Your doctor may prescribe an NSAID (such as diclofenac or naproxen) or a medicine called colchicine to help prevent or to deal with attacks of gout – especially in the early stages of allopurinol treatment.

Mixing allopurinol with herbal remedies and supplements

There's not enough information to say whether complementary medicines, herbal remedies and supplements are safe to take with allopurinol. They are not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.