may Bactrim increase mtx's toxicity ?

[Alysia]

we were asking not long ago, that question. the answer is YES.
I just saw in the vasculitis group, some people wrote about it.
here is a link:
http://www.rheumatology.org/Practice/Clinical/Patients/Medications/Methotrexate_(Rheumatrex,_Trexall)/
bottom line (I copy):
Trimethoprim (Bactrim or Septra), an antibiotic often used for respiratory and urinary infections, may increase the toxicity of methotrexate

[annekat]

Yes, we have talked about this. The literature says that Bactrim "could" or "may" increase the toxicity of MTX. This is why my drug insurance company would not cover my MTX while I was taking Bactrim, even though my doc had prescribed them together knowing about this possibility. It took a couple of appeals and conversations between him and the insurance company docs for them to approve it for a number of months. My doc says that something would show up in my blood tests if there was a problem. So it is just one of those things where there are pros and cons.... without the Bactrim, my lungs are not protected from the special strain of pneumonia that can occur in immunosuppressed people. I might be able to get along without the Bactrim. But if I stopped it and then got the pneumonia, I would be disappointed. So it is a gamble either way.

That is a good info sheet on MTX, though, and I have bookmarked it in my Health folder.