What are thiopurines?

Donna Hill Howes, RN
Family Practitioner

Thiopurines are drugs that suppress the immune system. They include mercaptopurine (Purixan) and azathioprine (Azasan, Imuran). These drugs are taken by mouth.

Thiopurines are often used to treat moderate or severe Crohn's disease. Because they take 2 to 4 months to reach full effect, they are usually given with a corticosteroid or TNF inhibitor, which work more quickly. They are also recommended to prevent relapse for people in remission after corticosteroid treatment of moderate or severe disease. But it is not clear if they prevent relapse for people in remission after surgery.

Thiopurines are mostly used to treat ulcerative colitis (UC) that has not improved with other drugs. They are recommended for mild or moderate active UC that affects a large portion of the colon and has not improved with aminosalicylates or corticosteroids. They are also recommended for people whose UC is in remission, but have had flare-ups while taking an aminosalicylate. They are also given for severe UC that is in remission after surgery or cyclosporine therapy. 

Thiopurines are not usually used to treat active Crohn's disease or UC in children. When they are used for active Crohn's, the child is also given a corticosteroid. Thiopurines are more often used to maintain remission in children with Crohn's or UC who are considered more likely to relapse or who cannot take aminosalicylates. 

This answer was adapted from Sharecare's award-winning AskMD app. Start a consultation now to find out what's causing your symptoms, learn how to manage a condition, or find a doctor.

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