This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.
Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
When these two medicines are taken together, your body may not process thiopurines properly.
What might happen:
The blood levels of your thiopurine may increase and cause toxic effects such as fever, chills, easy bruising or bleeding, black or tarry stools, blood in urine, or mouth or lip sores.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. They may already be aware of this drug interaction and may be monitoring you for it. If you develop any of the symptoms above, contact your doctor. It may be necessary to adjust the dose of your medicine. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Hitchings GH. Summary of informal discussion on the role of purine antagonists. Cancer Res 1963 Sep;23:1218-25.
2.Levine AS, Sharp HL, Mitchell J, Krivit W, Nesbit ME. Combination therapy with 6-mercaptopurine (NSC-755) and allopurinol (NSC-1390) during induction and maintenance of remission of acute leukemia in children. Cancer Chemother Rep 1969 Feb;53(1):53-7.
3.Nies AS, Oates JA. Clinicopathologic conference: hypertension and the lupus syndrome-- revisited. Am J Med 1971 Dec;51(6):812-4.
4.Berns A, Rubenfeld S, Rymzo WT Jr, Calabro JJ. Hazard of combining allopurinol and thiopurine. N Engl J Med 1972 Mar 30;286(13):730-1.
5.Zazgornik J, Kopsa H, Schmidt P, Pils P, Kuschan K, Deutsch E. Increased danger of bone marrow damage in simultaneous azathioprine- allopurinol therapy. Int J Clin Pharmacol Ther Toxicol 1981 Mar;19(3):96-7.
6.Brooks RJ, Dorr RT, Durie BG. Interaction of allopurinol with 6-mercaptopurine and azathioprine. Biomed Pharmacother 1982;36(4):217-22.
7.Krowka MJ, Breuer RI, Kehoe TJ. Azathioprine-associated pulmonary dysfunction. Chest 1983 Apr;83(4):696-8.
8.Zimm S, Ettinger LJ, Holcenberg JS, Kamen BA, Vietti TJ, Belasco J, Cogliano-Shutta N, Balis F, Lavi LE, Collins JM, et al. Phase I and clinical pharmacological study of mercaptopurine administered as a prolonged intravenous infusion. Cancer Res 1985 Apr;45(4):1869-73.
9.Cox GJ, Robertson DB. Toxic erythema of palms and soles associated with high-dose mercaptopurine chemotherapy. Arch Dermatol 1986 Dec; 122(12):1413-4.
10.Boyd IW. Allopurinol-azathioprine interaction. J Intern Med 1991 Apr; 229(4):386.
11.Zimm S, Collins JM, O'Neill D, Chabner BA, Poplack DG. Inhibition of first-pass metabolism in cancer chemotherapy: interaction of 6-mercaptopurine and allopurinol. Clin Pharmacol Ther 1983 Dec; 34(6):810-7.
12.Anonymous. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 4-1972. N Engl J Med 1972 Jan 27; 286(4):205-12.
13.Anonymous. Hypertension and the lupus syndrome. Am J Med 1970 Oct; 49(4):519-28.
14.Purinethol (mercaptopurine) US prescribing information. Gate Pharmaceuticals May, 2011.