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Starting azathioprine -- when do side effects or signs of intolerance typically show up?


So yeah, like the title says, I'm starting azathioprine (adding it to infliximab), and tonight is my second night taking it. I'm starting on 150mg (I'm a large human), and we're going to see how I tolerate it. For those of you who have tried it but couldn't tolerate it, when did you know? Was it immediate, or did it take some time before your body let you know that it wasn't agreeing with you? For those of you who have been taking it successfully, when did side effects (if any) start showing up?


Well-known member
Hi jdtm
I was on azathioprine a couple of years ago unfortunately it did not agree with me and I ended up in hospital with pancretitus .
I was on it about a month before i started with severe upper gastric pain plus continual vomiting.
I have not tolerated any of the usual meds Mesalmine, mercapectapurne & methetrexate.
I am not on any meds at the moment just had a capsule endoscopy to look at my small bowel see the consultant in October.
I hope you have a better outcome and it works for you.
For me it was a case of increasing fatigue over a couple of months and then just feeling very ill in a vague way (I think they call it general malaise, basically very weak dizzy, bit sick, no appetite, hard to get out of bed or do anything) but like the poster above I also reacted to other drugs (6mp, infliximab) so hopefully if you are tolerating infliximab that’s a good sign. The main thing to keep on top of is blood tests which will flag if liver struggling or blood cells dropping. I have been able to tolerate entyvio so there are options for sensitive bodies. Good luck.
I'm on Stelara and Azathioprine (as well as Cipro & Flagyl), but I definitely noticed a fairly consistent fatigue with the addition of Azathioprine. I have tolerated fairly well otherwise but the fatigue is a constant battle. Wishing you well!
I was on azathiaprine for almost six years. No side effects that I felt. However, I went to see a specialist and he thought that 6 years was too long and said I should go on Methotrexate. Never did go on that because I didn't like the side effects. So know I am just on Remicade every 8 weeks and things are good. However, I have elevated AST. Normal ALT. So I wonder if it is a long term effect of the azathiaprine. I have taken many blood tests, even a liver biopsy and everything comes back normal. Anyone else have blood issues?
I’ve been on Methotrexate since 2011. My GI says to keeps me in remission in conjunction with the Remicade. My blood work is perfect and my GI couldn’t be happier.


I'm too new to taking azathioprine to know about my blood levels yet. I don't feel like I'm having any bad reactions as of yet, but I'd imagine that a blood test will be in order at my next appointment (late October). I'm also curious to see if I've developed antibodies to infliximab -- there's a blood test for that, right?
Yes there is a blood test for Infliximab anti-bodies. I’ve had it done once - I had no anti-bodies. I’ve been on and off Remicade three times now due to surgeries. Was able to re-start it every time.