Take this medicine only as directed by your doctor. Do not take more or less of it, and do not take it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Taking too much may increase the chance of side effects, while taking too little may not improve your condition.

Thioguanine is sometimes given together with certain other medicines. If you are using a combination of medicines, make sure that you take each one at the right time and do not mix them. Ask your health care professional to help you plan a way to take your medicine at the right times.

While you are using thioguanine, your doctor may want you to drink extra fluids so that you will pass more urine. This will help prevent kidney problems and keep your kidneys working well.

Thioguanine sometimes causes nausea and vomiting. However, it is very important that you continue to take this medicine, even if you begin to feel ill. Do not stop taking this medicine without first checking with your doctor. Ask your health care professional for ways to lessen these effects.

If you vomit shortly after taking a dose of thioguanine, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.

Dosing

The dose of thioguanine will be different for different patients. The dose that is used may depend on a number of things, including what the medicine is being used for, the patient's weight, and whether or not other medicines are also being taken. If you are taking thioguanine at home, follow your doctor's orders or the directions on the label. If you have any questions about the proper dose of thioguanine, ask your doctor.

Missed dose

If you miss a dose of this medicine, do not take the missed dose at all and do not double the next one. Instead, go back to your regular dosing schedule and check with your doctor.

Storage

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For thioguanine, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to thioguanine.

Pregnancy Tell your doctor if you are pregnant or if you intend to have children. There is a chance that this medicine may cause birth defects if either the male or female is taking it at the time of conception or if it is taken during pregnancy. In addition, many cancer medicines may cause sterility which could be permanent. Although this has not been reported with this medicine, the possibility should be kept in mind.

Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are taking thioguanine. Tell your doctor right away if you think you have become pregnant while taking thioguanine.

Breast-feeding Tell your doctor if you are breast-feeding or if you intend to breast-feed during treatment with this medicine. Because thioguanine may cause serious side effects, breast-feeding is generally not recommended while you are receiving it.

Children Although there is no specific information about the use of thioguanine in children, it is not expected to cause different side effects or problems in children than it does in adults.

Older adults Many medicines have not been tested in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information about the use of thioguanine in the elderly.

Other medicines Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking thioguanine, it is especially important that your health care professional know if you are taking any of the following:

• Antithyroid agents (medicine for overactive thyroid) or
• Azathioprine (e.g., Imuran) or
• Chloramphenicol (e.g., Chloromycetin) or
• Colchicine or
• Flucytosine (e.g., Ancobon) or
• Interferon (e.g., Intron A, Roferon-A) or
• Plicamycin (e.g., Mithracin) or
• Zidovudine (e.g., Retrovir) or
• If you have ever been treated with x-rays or cancer medicines Thioguanine may increase the effects of these medicines or radiation therapy on the blood

• Probenecid (e.g., Benemid) or
• Sulfinpyrazone (e.g., Anturane) Thioguanine may increase the concentration of uric acid in the blood, which these medicines are used to lower

• Chickenpox (including recent exposure) or
• Herpes zoster (shingles) Risk of severe disease affecting other parts of the body

• Gout (history of) or
• Kidney stones (history of) Thioguanine may increase levels of uric acid in the body, which can cause gout or kidney stones

• Infection Thioguanine can reduce immunity to infection

• Kidney disease or
• Liver disease Effects may be increased because of slower removal of thioguanine from the body