Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Purinethol (Mercaptopurine).

Anemia: Purinethol (Mercaptopurine) may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Birth control: Effective birth control should be practiced if either partner is using Purinethol (Mercaptopurine) as Purinethol (Mercaptopurine) may harm the baby if used during pregnancy. If you become pregnant while taking Purinethol (Mercaptopurine), contact your doctor immediately.

Bleeding: Purinethol (Mercaptopurine) can reduce the number of platelet cells in the blood. Platelets help the blood to clot, and a shortage could make you bleed more easily. Tell your doctor of any signs that your blood is not clotting as quickly. Such symptoms may include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Infection and vaccines: As well as killing cancer cells, Purinethol (Mercaptopurine) can reduce the number of cells that fight infection in the body (white blood cells). Avoid contact with people with contagious infections and tell your doctor if you begin to notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Also tell your doctor if you have been vaccinated, or are planning to be vaccinated with a live vaccine.

Kidney function: Kidney Disease or reduced kidney function may cause Purinethol (Mercaptopurine) to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how Purinethol (Mercaptopurine) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Purinethol (Mercaptopurine), and whether any special monitoring is needed.

Liver function: Purinethol (Mercaptopurine) can reduce liver function and can cause liver failure. If you have liver problems, discuss with your doctor how Purinethol (Mercaptopurine) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Purinethol (Mercaptopurine), and whether any special monitoring is needed. Your doctor will test your liver function regularly with blood tests while you are taking Purinethol (Mercaptopurine).

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Second cancers: Purinethol (Mercaptopurine) can cause damage to other normal genes and cells. Rarely there have been reports of certain types of leukemia and lymphoma developing in people who have been treated with Purinethol (Mercaptopurine). Discuss any concerns you may have with your doctor.

Tumour lysis syndrome: Purinethol (Mercaptopurine), like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea, shortness of breath, notice cloudy urine or joint pain. This is called tumour lysis syndrome. Your doctor may prescribe some medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.

Pregnancy: There is a possibility of birth defect if either the man or woman is using Purinethol (Mercaptopurine) at the time of conception, or if it is taken during pregnancy. Effective birth control should be practiced while using Purinethol (Mercaptopurine). Purinethol (Mercaptopurine) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while you or your partner are taking Purinethol (Mercaptopurine), contact your doctor immediately.

Breast-feeding: Purinethol (Mercaptopurine) passes into breast milk. Because of the risks associated with Purinethol (Mercaptopurine), a decision should be made to cease breast-feeding or discontinue the medication, taking into account the importance of the medication to the mother. Women who are taking Purinethol (Mercaptopurine) should not breast-feed.

Seniors: Seniors may be more likely to experience side effects from Purinethol (Mercaptopurine). Discuss any concerns you have with your doctor.