Azathioprine

Drug Name
Azathioprine

Brand Name(s)
Imuran®, generics

Drug Class
Prescription medication

Azathioprine may be used to treat a number of inflammatory conditions such as Granulomatosis with Polyangiitis (GPA; formerly known as Wegener’s granulomatosis) and lupus.  Azathioprine can also be used to treat rheumatoid arthritis, but it is no longer commonly used for this condition. 

  • What is azathioprine used for?
    Azathioprine may be used to treat a number of inflammatory conditions such as Granulomatosis with Polyangiitis (GPA; formerly known as Wegener’s granulomatosis) and lupus.  Azathioprine can also be used to treat rheumatoid arthritis, but it is no longer commonly used for this condition. 
  • How is azathioprine administered?
    Azathioprine is taken orally in pill form.
     
  • What is the typical dose and when do I take it?
    Azathioprine is available in 50 mg tablets.
     
    The typical dose is 50 – 100 mg/day (maximum 150 mg/day)
     
    The dose of azathioprine depends on your body weight.
     
    If you have poor renal function you may need a lower daily dose.  Please discuss this with your healthcare provider.
     
  • How long will it take to work?

    Like with many medications used to treat inflammatory conditions, you will not feel the effects of azathioprine right away. Most people start noticing the effects about 6 to 12 weeks after they start to take the medication, however, the full benefit of azathioprine may not be evident for up to 3 – 6 months. It is important to be patient and continue taking your medication.

  • When should I not take azathioprine and call my doctor?

    Taking azathioprine can make it more difficult for your body to fight infections. If you have a fever, have been prescribed an antibiotic or think you may have an infection, contact your azathioprine prescriber.
     
    You may need to stop taking azathioprine if you are having surgery until you are healed and there is no sign of infection.  Please discuss this with your prescriber. 

    Ideally, your vaccinations should be up to date prior to starting azathioprine.  Before receiving any vaccinations while taking azathioprine, you should speak with your healthcare provider. 
     
    Men who are planning pregnancy with their partner and women who are pregnant or planning to get pregnant should avoid using azathioprine.  If you or your partner is planning to get pregnant please discuss this with your prescriber. Any woman who is breast-feeding should also avoid azathioprine if possible.  Because of the potential for adverse reactions in nursing infants, a decision should be made with your healthcare provider on whether or not to discontinue nursing or the medication, taking into account the importance of the drug to the mother.
     
    Drinking alcohol while taking azathioprine has the potential to harm your liver, so it is best to avoid or restrict alcohol while taking the medication.
     
    Anyone who has had a previous allergic reaction to azathioprine should avoid the medication.
     
    Azathioprine interacts with a number of other medications, including medications commonly used to treat gout. Please speak with your healthcare provider about whether any of the other medications you currently take interact with azathioprine.
     

  • What are the side effects of azathioprine?
    Like all medications, taking azathioprine carries some risk of side effects, which must be balanced with the potential benefits. In general, the risk of your condition decreasing your quality of life is much greater than the risks of side effects from azathioprine. When monitored properly the vast majority of side effects are rare, generally improve over time and are reversible.

    The most common side effects of azathioprine are nausea and feeling unwell or feeling. This can improve over time as you get used to taking the medication.

    Azathioprine may affect your liver function and blood counts. This should be closely monitored with routine blood work. 

    In some rare cases, people taking azathioprine may experience a rash or thinning of the hair/hair loss.  Please contact your prescriber should these side effects develop.

    Prolonged use of azathioprine has rarely been associated with an increased risk of certain types of cancer.  The exact role of azathioprine in the development of cancer is currently unknown.  Please speak with your healthcare provider if you have any questions or concerns.
     
  • What helps to reduce side effects?

    Take your azathioprine as prescribed and contact your health-care provider if you have any concerns while taking the medication.
     
    Taking azathioprine with food may help reduce nausea and stomach upset. 

  • Do I need any monitoring while taking azathioprine?

    You will need regular blood tests to make sure azathioprine is not affecting your liver and blood counts.  When you begin taking azathioprine your prescriber may request blood work more frequently (every one to two weeks) for a period of time.  If you have no issues with the medication during this time, blood tests will be required less frequently (every 1 to 3 months).



This information was last updated January 2020, with expert advice from:

Jason Kielly, B.Sc. (Pharm.), Pharm.D.
Associate Professor, School of Pharmacy, Memorial University of Newfoundland
Clinical Pharmacist, Rheumatic Health Program, Eastern Health

Hamidreza Izadpanah , Pharm.D.

 

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