Allopurinol is a drug used to treat and prevent gout and kidney stones; it works by reducing the level of urate (uric acid) in the blood.

Gout is caused by high urate levels in the blood. The body naturally produces uric acid, which is passed out in urine, but if too much of it is produced, it will form urate crystals in your joints. This can slowly happen for several years without symptoms, and it causes gout attacks and kidney stones.

Allopurinol can help lower urate levels, prevent new crystals from forming, and, with time, dissolve the already-formed crystals. It is also used for reducing uric acid levels after chemotherapy.

Dosage

Allopurinol should be taken by mouth after a meal, usually once daily. Your doctor will prescribe the dosage based on your condition and response to treatment; however, if your daily dose is more than 300 mg, you have to take it in divided doses during the day.

It is best to take at least 8 glasses of water daily when taking this drug, and your doctor may also prescribe ascorbic acid or vitamin C to decrease the acidity of your urine. 

When treating gout with this drug, it may take several weeks to notice the effect, so during this time, your doctor may also prescribe some pain reliever because allopurinol is not a pain medication. 

Side Effects of Allopurinol

Some people may notice signs of allergic reaction to this drug, such as difficulty breathing, swelling of the throat or face, and hives. The mild side effects may include stomach upset, diarrhoea, nausea, skin rash, fever, muscle aches and yellowing of the eyes and skin. 

Allopurinol may also cause more severe side effects, including:

• Liver problems.
• Numbness/ tingling of the arms and legs.
• Easy bruising and bleeding.
• Kidney problems
• Sore throat.
• Loss of appetite.
• Unusual tiredness.
• Weight loss.
• Vision chganes/eye pain.

Precautions

Before taking this medication, tell your doctor if you have had any of the following:

• Liver disease.
• Kidney disease.
• Diabetes.
• Receiving chemotherapy.
• Congestive heart failure.
• High blood pressure.
• Allergies to allorupinol.
• Unusual diet such as fasting.

This drug can make you drowsy; do not drive or do anything that requires alertness after taking it. Allopurinol may cause harm to an unborn baby; do not take it if you are pregnant, and tell your doctor if you plan to become pregnant. It also has undesirable effects on an infant child, so if you are breastfeeding, discuss the risks and benefits of the drug with your doctor before taking it.