Thioguanine is used to treat acute nonlymphocytic leukemia (a type of blood cancer), sometimes in combination with other cancer medicines.

Thioguanine may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Thioguanine comes as a tablet to take by mouth usually once a day. The length of treatment depends on the types of drugs you are taking, how well your body responds to them, and the type of cancer you have. Take thioguanine at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take thioguanine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor may increase or decrease your dose of thioguanine during your treatment. This depends on how well the medication works for you and on the side effects that you experience. Talk to your doctor about how you are feeling during your treatment. Continue to take thioguanine even if you feel well. Do not stop taking thioguanine without talking to your doctor

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

You must remain under the care of a doctor while taking thioguanine.

You may be given other medications to help prevent certain side effects. Keep using these medicines for as long as your doctor has prescribed.

Thioguanine can increase your risk of bleeding or infection. You will need frequent blood tests, and your next dose may be delayed based on the results.

Thioguanine can also cause liver damage. You may need weekly or monthly blood tests to check your liver function.

Store at cool room temperature away from moisture and heat.

You should not use thioguanine if you are allergic to it, or if you have ever used thioguanine or mercaptopurine and they were not effective in treating your condition.

Tell your doctor if you've ever had liver problems.

Thioguanine may be more effective in younger people than in older people. How well you respond to thioguanine may also depend on whether you've had prior treatments for leukemia.

Thioguanine may harm an unborn baby. Use effective birth control to prevent pregnancy, and tell your doctor if you become pregnant.

You should not breastfeed while taking thioguanine.

Call your doctor for instructions if you miss a dose of thioguanine.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, sweating, feeling light-headed, decreased urination, fever, chills, or other signs of infection.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unless your doctor tells you otherwise, continue your normal diet.

Drink plenty of fluids during your treatment with thioguanine.

Do not receive a "live" vaccine while using thioguanine. Live vaccines include measles, mumps, rubella (MMR), rotavirus, typhoid, yellow fever, varicella (chickenpox), zoster (shingles), and nasal flu (influenza) vaccine.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using thioguanine and call your doctor if you have possible signs of liver damage:

• stomach bloating, rapid weight gain;

• unusual tiredness, trouble breathing while lying down;

• nausea, loss of appetite, upper stomach pain; or

• dark urine or jaundice (yellowing of the skin or eyes).

Thioguanine may cause serious side effects. Call your doctor at once if you have:

• easy bruising, unusual bleeding;

• bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds; or

• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects of thioguanine may include:

• fever, chills, or other signs of infection; or

• high uric acid levels.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Thioguanine can harm your liver, especially if you also use certain medicines for infections, tuberculosis, birth control, hormone replacement, high cholesterol, heart problems, high blood pressure, seizures, pain, or arthritis (including Tylenol, Advil, Motrin, or Aleve).

Tell your doctor about all your other medicines, especially medicines to treat ulcerative colitis such as balsalazide, mesalamine, olsalazine, mesalamine, or sulfasalazine.

Other drugs may affect thioguanine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body's response to thioguanine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.