Azathioprine: what it is for, how to take it and side effects

Azathioprine is an immunosuppressant indicated for the treatment of autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis or Crohn’s disease, or to prevent rejection after liver, kidney or heart transplants, for example.

This medicine works by reducing the action of the immune system, preventing healthy cells in the body or the transplanted organ from being attacked and destroyed by the immune system itself.

Azathioprine can be provided free of charge by the SUS or purchased in pharmacies or drugstores, in the form of a 50 mg tablet, with the names Imussuprex or Imuran, for example, and should only be used with medical advice.

What is it for

Azathioprine is indicated for the treatment of autoimmune diseases, such as:

• Severe rheumatoid arthritis;
• Systemic lupus erythematosus (SLE);
• Crohn’s disease or ulcerative colitis;
• Multiple sclerosis or systemic sclerosis;
• Dermatomiositis or polimiositis;
• Myasthenia gravis;
• Autoimmune hepatitis;
• Pemphigus vulgaris;
• Polyarteritis nodosa;
• Autoimmune hemolytic anemia;
• Idiopathic thrombocytopenic purpura (ITP);
• Non-infectious uveitis.

Furthermore, azathioprine is indicated to reduce the risk of rejection of organ transplants in children or adults, such as kidneys, heart or liver, and can be used in combination with corticosteroids or other immunosuppressive medications. Check out the list of the main immunosuppressant medications.

How to drink

Azathioprine should be taken orally, with a glass of water, and it is recommended to take the tablet at least 1 hour before or 3 hours after a meal or drink milk.

Azathioprine doses vary according to the condition being treated and include:

1. Autoimmune diseases

The normally recommended starting dose for adults is 1 to 3 mg per kg of body weight, per day.

This dose can be adjusted by the doctor according to the response to treatment and evaluation of blood tests.

2. Pprevention of transplant rejection

The normally recommended dose is 5 mg per kg of body weight, on the first day of treatment.

Maintenance doses range from 1 to 4 mg per kg of body weight per day, which must be indicated by the doctor according to the person’s needs and evaluation of blood tests.

For the treatment of transplant rejection in children, the normally recommended doses are the same as for adults.

Care during treatment

It is important not to stop treatment with azathioprine on your own, without being advised by your doctor.

In addition, you should take azathioprine at the right times as indicated by your doctor and have regular medical appointments to monitor the effectiveness of the treatment and the emergence of side effects.

Possible side effects

The most common side effects of azathioprine are nausea, diarrhea, stomach pain, hair loss, or skin rash. Know how to identify the symptoms of skin rash.

Furthermore, another common side effect of azathioprine is the increased risk of infections, as it reduces the immune system’s action to combat viruses, bacteria or fungi, and reactivation of the varicella zoster or hepatitis B virus, for example, may also occur.

Although rarer, azathioprine can cause anemia, colitis, diverticulitis, intestinal perforation, liver damage, lymphoma, skin cancer, Kaposi and non-Kaposi sarcoma, cervical cancer on siteacute myeloid leukemia or myelodysplastic syndrome.

When azathioprine is used with other immunosuppressants, there is an increased risk of serious brain infection, called progressive multifocal leukoencephalopathy, and should be reported to the doctor immediately if the person presents symptoms such as difficulty speaking or thinking, vision problems or muscle disorders.

Who shouldn’t use

Azathioprine should not be used during pregnancy or breastfeeding, or by people who are allergic to azathioprine, mercaptopurine or any other component of the tablet.

This medicine should also not be used by people taking ribavirin, and should be used with caution in people who have kidney disease and/or liver failure.

During treatment and up to 3 months after the end of treatment with azathioprine, the person should not receive vaccines with live or attenuated organisms, as they can cause infection.