Azathioprine is used to prevent organ rejection in people who have received a kidney transplant. It is usually taken along with other medications to allow your new kidney to function normally. Azathioprine is also used to treat rheumatoid arthritis. In this condition, the body's defense system (immune system) attacks healthy joints. Azathioprine belongs to a class of drugs known as immunosuppressants. It works by weakening the immune system to help your body accept the new kidney as if it were your own (in the case of an organ transplant) or to prevent further damage to your joints (in the case of rheumatoid arthritis).

Talk to your doctor about the risks and benefits of azathioprine, especially when used in children and young adults.

Take this medication by mouth as directed by your doctor, usually once or twice daily. Take this medication with food to reduce stomach upset.

The dosage is based on your medical condition, weight, and response to treatment. Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of serious side effects will increase.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.

For the treatment of arthritis, it may take up to 2 months before your symptoms get better. Tell your doctor if your condition does not get better after 3 months of treatment.

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets.

Before taking azathioprine, tell your doctor or pharmacist if you are allergic to it, or to mercaptopurine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, cancer, certain enzyme disorders (TPMT deficiency, NUDT15 deficiency).

Azathioprine may rarely increase your risk of developing certain types of cancer (such as lymphoma, skin cancer). This risk is higher in people using azathioprine after an organ transplant and in children/young adults being treated for certain bowel diseases (such as Crohn's disease, ulcerative colitis). Keep all medical and lab appointments. Tell your doctor right away if you develop any of the following symptoms: unusual skin changes, change in the appearance/size of moles, unusual growths/lumps, swollen lymph nodes, swollen abdomen, unexplained weight loss, night sweats.

This medication may decrease bone marrow function, an effect that may lead to a low number of blood cells such as red cells, white cells, and platelets. This effect can cause anemia, decrease your body's ability to fight an infection, or cause easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms: unusual tiredness, pale skin, signs of infection (such as sore throat that doesn't go away, fever, chills), easy bruising/bleeding.

Nausea or vomiting may occur. Taking this medication after meals may help lessen these effects. Temporary hair loss may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Tell your doctor right away if you have any serious side effects, including: diarrhea, new or worsening joint/muscle pain.

Get medical help right away if you have any very serious side effects, including: symptoms of liver disease (such as nausea/vomiting that doesn't stop, stomach/abdominal pain, dark urine, yellowing eyes/skin).

Interactions

Some products that may interact with this drug are febuxostat, past or present use of certain cancer drugs (such as cyclophosphamide, melphalan), other drugs that weaken the immune system/increase the risk of infection (such as rituximab, tofacitinib).

Azathioprine is very similar to mercaptopurine. Do not use medications containing mercaptopurine while using azathioprine.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at a regular time. Do not double the dose to catch up.