Crohn's Disease Forum » Forum Wiki » Azathioprine




Azathioprine, also known as "Imuran" is a "pro-drug", that is one that gets converted or metabolised into the required substance, for Mercaptopurine (6MP). Therefore azathioprine has many of the same benefits and side effects as 6MP. Azathioprine is less toxic.[citation needed]

Azathioprine is most effective on rapidly dividing cells [such as Immune cells (T-Lymphocytes), embryonic / fetal tissue, etc.] and acts by inhibiting DNA and RNA synthesis in cells. Azathioprine (or the metabolite 6-MP) is used in Inflammatory and Autoimmune Diseases, Following organ or tissue transplantation to prevent rejection, or as an anti - cancer medication.

Smaller doses of Azathioprine are Anti - Inflammatory while larger doses are Cytotoxic and / or Immunosuppressive. Azathioprine works by reducing immune cell replication cells and helps to slow down the inflammatory process implicated in Inflammatory Bowel Disease.

Azathioprine and Mucosal Healing

Azathioprine has been shown to promote mucosal healing which is thought to be a potential variable in long term remission. One study of 15 patients found that 6 had complete mucosal healing, 5 had barely just surface level erosions, and 3 had partial mucosal healing.[1] In another study of 20 patients with either ileitis or Crohn's Colitis, 80% of the Crohn's Colitis patients experienced complete or or near complete mucosal healing and 69% of the patients with Ileitis.[2]


The maintenance dose of Azathioprine tends to be is 2-2.5 mg/kg per day. However, weight based dosing has been shown to correlate poorly with 6-TGN levels which are thought to correlate with the therapeutic affect of Azathioprine. As such, 6-TGN levels should be monitored. It has been shown that splitting a dose to morning and evening can help lower 6-MMP levels while maintaining 6-TGN levels.[3]

Consuming milk products around the time you take your Azathioprine may interfere with its bioavailability. It is best to avoid taking milk products for at least 2 hours before and 2 hours after you take your dose.[4]

Side Effects

Short term side effects can include dizziness, nausea and vomiting, diarrhea and headaches.

More serious side effects may affect the liver and pancreas. If you are taking azathioprine, it is important that you have regular blood tests. There is an enzyme or genetic test (TPMT or Thiopurine Methyltransferase) that may be offered before starting treatment. This may predict those who are more at risk of severe side effects, however, regular blood tests are still important).

As azathioprine is an immune suppressant, you may notice that you are more prone to illnesses such as colds. Some people's immune systems may be suppressed too much, again regular blood tests should check for this.

Long term use of azathioprine is associated with an increased risk of lymphoma. However, it is well regarded that the increased risks are outweighed by the benefits.[3]

Another possible side effect is increased MCV.

Azathioprine Not Recommended in Pregnancy

Azathioprine is a Pregnancy Category D Drug. This means that there is evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks. For more information on Pregnancy Categories for Medication please CLICK HERE.

6-MP As An Alternative

Those who are unable to tolerate Azathioprine due to nausea, vomiting, diarrhea or headaches may do better with 6-MP (60%) but those who experience hepatoxicity or pancreatitis on Azathioprine will likely not. 48% who experience arthritis or muscle pain may do better on 6-MP.[3]

Drug Interactions

Caution is recommended if azathioprine is taken alongside allopurinol (used to treat gout). Doses will need to be adjusted.

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04-28-2013, 11:43 AM   #1
Join Date: Mar 2013
Location: Washington
This says to avoid milk when taking azathioprine. Does that include milk substitute like soy/almond/rice milk? What exactly is the problem? The calcium or some proteins in animal milk? Or something else?

Never mind, I read the article linked to it. Sorry
04-28-2013, 11:46 AM   #2
David's Avatar
Join Date: Feb 2006
Location: Naples, Florida
The problem is with the high levels of Xanthine oxidase in the cow's milk which interferes with the medication. Your alternatives should be fine BUT may sure they don't contain carrageenan!
It's good to be back
04-28-2013, 12:49 PM   #3
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bigtruck's Avatar
Join Date: Feb 2009
Location: United Kingdom
Very interesting about the mucosal healing.
04-28-2013, 01:06 PM   #4
xX_LittleMissValentine_Xx's Avatar
Join Date: May 2009
Location: Reading, United Kingdom
No one ever told me about milk! Been on Aza for almost 5 years. Oh well, hopefully only 5 months and I'll be off it.
Diagnosed with CD March 08 at 17
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