Understanding the immunosuppressants – Azathioprine and Mercaptopurine

October 28, 2021by Health Desk

Azathioprine (AZA) and 6-Mercaptopurine (6-MP) are immune suppressants or immunomodulators, which suppress or weaken the immune system when it is necessary. They are used with kidney transplant patients to support the new kidney being accepted. They are also used with autoimmune conditions, including Inflammatory Bowel Disease (IBD) and Rheumatoid Arthritis. These medications are used to maintain long-term remissions for people with IBD.

Azathioprine and 6-Mercaptopurine are both members of the thiopurine class of drugs. Both medications are slow acting with typical responses observed after 3-6 months of therapy. Because of this, they are often started simultaneously with faster acting medications, such as steroids.

These can be taken by injection or as a pill.

The most common side effects of Azathioprine and 6-Mercaptopurine are loss of appetite, nausea, and vomiting, especially if the dose is increased too rapidly. These symptoms can be minimized by taking the drug with meals.

Testing for tuberculosis and/or hepatitis may take place before starting treatment using these medications. If these diseases are present, the doctor may treat them prior to starting one of the thiopurines. Your doctor may monitor your blood count and liver enzymes while taking these medications, because of possible bone marrow suppression and liver complications. Make sure to keep all your doctor appointments, and discuss this with your doctor.

Skin Cancer

The use of Azathioprine is associated with increased risk of non-melanoma skin cancer and cervical abnormalities or cancer. Please talk to your doctor about getting regular skin examinations and cervical smears. Always use sunscreen and wear clothing for protection from the sun.

If you are taking Azathioprine or Mercaptopurine, you should not receive live vaccines, such as MMR (measles, mumps and rubella), yellow fever, nasal flu or polio vaccines. You should also avoid coming into contact with anyone who has recently received a live vaccine, as there is a chance the infection could be passed to you.


Even though very rare, Lymphoma (cancer of infection-fighting cells, called lymphocytes) has occurred in people who have taken these medications. Discuss this with your doctor. Also, talk with your doctor immediately if you experience a swollen gland, night sweats, shortness of breath, or weight loss without trying.

AZA and 6-MP can lower the number of platelets, which are necessary for proper blood clotting. Be careful when using a regular toothbrush, dental floss or toothpick. Check with your medical doctor before having any dental work done. In addition, be careful not to cut yourself when you are using sharp objects. Avoid contact sports or other situations where bruising or injury could occur. Check with your doctor immediately if you have unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin

Although rare, liver problems have also occurred with these medications. Talk with your doctor if you experience dark urine, tiredness, lack of hunger, upset stomach or stomach pain, light-colored stools, vomiting, or yellow skin or eyes.

AZA and 6-MP are not given to people who are pregnant or likely to become pregnant in the near future. These drugs may cause harm to an unborn baby.

Washing Hands

Suppressed immunity can be problematic and make you more prone to infections. Contact your doctor if you begin to feel unwell, or think you may have caught an infection. Wash your hands regularly, and avoid being around people who are sick.

Almost all medications come with benefits and risks. You and your doctor are partners in your healthcare and many decide to take these medications after weighing the benefits and risks. AZA and 6-MP are helpful in reducing or eliminating the need for steroids and maintaining remission when other medications have failed to do so.