Allopurinol

In Aotearoa New Zealand allopurinol is available as 100 mg and 300 mg tablets.

• The dose of allopurinol will be different for different people.
• Your doctor will usually start you on a low dose (usually 50 or 100 mg each day) and increase it very slowly over a few months.
• They will measure your uric acid level with a blood test and increase the allopurinol dose as much as needed until your uric acid level is less than 0.36 mmol/L. 
• It can take 6 to 12 months of taking allopurinol every day to get your level to less than 0.36 mmol/L.
• The usual long-term dose of allopurinol is 100 to 600 mg a day. Some people may need up to 900 mg daily. 
• Always take your allopurinol exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions. Know what dose you should be taking. If you are unsure, talk to your pharmacist.

You can use the following plan to help keep track of your allopurinol as you increase your daily dose.

My dose is:

• Timing: Take allopurinol once a day with a full glass of water. If you think allopurinol is causing stomach upset, try taking it with food. If you're taking more than 300 mg per day, you may wish to divide the dose and take it twice a day. Talk to your doctor about this
• Drink plenty of water: It's important to drink plenty of water while you're taking allopurinol because kidney stones can develop if you don't drink enough fluid.
• Missed dose: If you forget to take your dose of allopurinol, take it as soon as you remember. But if it's nearly time for your next dose, just take the next dose at the right time. Don't take double the dose.
• Keep taking allopurinol every day, even during a gout attack: If you stop taking it, even for a few days, your uric acid levels will rise and crystals will start to form. This can cause a gout attack and joint damage. Allopurinol is a long-term medicine – you'll probably need to take allopurinol for the rest of your life. 

You may have gout attacks when starting allopurinol

You may have gout attacks in the first few months as you're increasing your dose of allopurinol. If this happens, it may feel like your gout is getting worse, but it’s not. As allopurinol reduces the amount of uric acid your body makes, some of the crystals in your joints dissolve. As the crystals dissolve, they can cause a gout attack.

• To manage this, when you start allopurinol, your doctor will prescribe preventative medication such as colchicine, non-steroidal anti-inflammatory drugs (NSAIDs) or prednisone. It's important to take this regularly, for up to 6 months, while you are starting allopurinol. 
• Keep taking allopurinol every day, even during a gout attack.
• As your uric acid level decreases over time you're less likely to get gout flares.
• Keeping your uric acid level below 0.36 mmol/L, will help stop your gout attacks. This may take 6 to 12 months of taking allopurinol every day.

Blood tests

When you first start taking allopurinol, you'll need to have blood tests to monitor your uric acid levels every 4 weeks until the target uric acid level has been reached. Then you'll need blood tests every 3 to 6 months to check your uric acid level and your kidney function. This can be done either at the blood lab, your doctors clinic or at some pharmacies.

Here are some things to know when you're taking allopurinol. Other things may be important as well, so ask your healthcare provider what you should know about.

• Skin rash: You may get a skin rash or itching (about 2 in every 100 people who take allopurinol will have a skin rash). This can happen anytime while taking allopurinol, but especially in the first few months while your dose is being increased. If this happens, stop taking allopurinol and contact your doctor immediately – even if the rash is mild. This can develop into a severe allergic reaction.
• Other medicines: Allopurinol may interact with other some other medicines, herbal supplements and Rongoā Māori, so check with your doctor or pharmacist before starting allopurinol and before starting any new products.
• If I'm having a gout attack, will an extra dose of allopurinol help? No. Allopurinol is not a pain relief medicine. If you have an attack of gout while taking allopurinol, keep taking it at the same dose. Don't stop taking it. Your doctor will advise you to take a pain relief medicine, eg, NSAIDs (ibuprofen, diclofenac, naproxen), or prednisone or colchicine. You can also apply ice-packs and rest the painful joint to reduce pain. See your doctor if the pain and inflammation doesn't get better in 24 hours.
• What if allopurinol doesn't help? After starting allopurinol, your doctor will monitor your pain and check your uric acid levels. If after a few months of taking  allopurinol, your symptoms don't improve and your uric acid levels stay high, your doctor may try you on other medicines (eg, febuxostat, probenecid or benzbromarone).

Like all medicines, allopurinol can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.