Drug Interactions With Allopurinol
Allopurinol Interactions Explained
The following sections explain in detail the potentially negative interactions that can occur when allopurinol is combined with any of the drugs listed above.
There have been reports indicating that ACE inhibitors may increase the risk of dangerous reactions to allopurinol, although this is not known for certain. Check with your healthcare provider before taking allopurinol with an ACE inhibitor.
Amoxicillin or Ampicillin
Combining allopurinol with amoxicillin or ampicillin may increase the risk of skin rashes (including very dangerous skin reactions). Check with your healthcare provider before taking these medications together.
There have been reports indicating that antacids may decrease the absorption of allopurinol into the body. It is probably a good idea to take antacids and allopurinol at different times of the day, if possible.
If you take allopurinol with azathioprine, your dose of azathioprine must be reduced significantly, in order to prevent serious side effects of azathioprine.
Allopurinol can increase the level of chlorpropamide in your blood, increasing your risk of low blood sugar (hypoglycemia). You may need to monitor your blood sugar more closely when starting or stopping allopurinol (or even when changing your dose).
Allopurinol may increase the toxic effects of cyclophosphamide. Check with your healthcare provider before taking these medications together.
Allopurinol may increase the level of cyclosporine in the blood, increasing the risk of side effects. Your healthcare provider should measure the level of cyclosporine in your blood (using a blood test) when you start or stop allopurinol (or even when you change your allopurinol dose).