Thioguanine Side Effects

Medically reviewed by Drugs.com. Last updated on Jul 11, 2024.

Applies to thioguanine: oral tablet.

Precautions

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.

Serious side effects of thioguanine

Along with its needed effects, thioguanine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking thioguanine:

Get emergency help immediately if any of the following symptoms of overdose occur while taking thioguanine:

Symptoms of overdose

• blurred vision
• cloudy urine
• confusion
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• dry mouth
• general feeling of discomfort or illness
• increased sweating
• unusual tiredness or weakness
• vomiting

Other side effects of thioguanine

Some side effects of thioguanine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to thioguanine: oral tablet.

Hematologic adverse events

• Very common (10% or more): Bone marrow failure, splenomegaly, thrombocytopenia
• Frequency not reported: Agranulocytosis^[Ref]

Gastrointestinal

• Very common (10% or more): Varices esophageal
• Common (1% to 10%): Stomatitis, nausea, vomiting, diarrhea, anorexia
• Rare (less than 0.1%): Necrotizing colitis, perforation^[Ref]

Hepatic

• Very common (10% or more): Veno-occlusive liver disease, hyperbilirubinemia, hepatomegaly, portal hypertension, hepatic enzymes increased, blood alkaline phosphatase increased, gamma glutamyltransferase increased, jaundice, portal fibrosis, nodular regenerative hyperplasia, peliosis hepatitis
• Common (1% to 10%): Veno-occlusive liver disease
• Rare (less than 0.1%): Hepatic necrosis

Renal

• Common (1% to 10%): Hyperuricemia, hyperuricosuria, urate nephropathy^[Ref]

Dermatologic

• Frequency not reported: Photosensitivity^[Ref]

Immunologic

• Frequency not reported: Transient treatment-related megaloblastic marrow changes^[Ref]

Metabolic

• Very common (10% or more): Weight increased (due to fluid retention and ascites)
• Common (1% to 10%): Hyperuricemia^[Ref]

Genitourinary

• Common (1% to 10%): Urate nephropathy^[Ref]

See also:

Further information

Thioguanine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer