It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.
Do not use this medicine if thioguanine or mercaptopurine (Purinethol®) has not been effective in treating your condition in the past.
Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine. If you think you have become pregnant while using this medicine, tell your doctor right away.
Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.
Thioguanine can lower the number of white blood cells in your blood temporarily, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:
If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in urine or stools, or pinpoint red spots on your skin.
Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
Avoid contact sports or other situations where bruising or injury could occur.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.