Vasculitis UK
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Methotrexate & Co-Trimoxazole (Septrim Forte) advice needed about taking both

Addenbrookes put my husband (he has WG) on Methotrexate and he was already on Bactrim/Septrim Forte/Co-Trioxazole. He's on 15mg Meth per week and 160mg/800mg Co-Trioxazole 3 times per week.

The Meth booklets said you should not take Co-Trioxazole with it but when I asked Addenbrookes, they said it was ok as it was a fairly low dose and would help protect his lungs.

We have now seen a new specialist in Devon who immediately insisted that the Co-Trioxazole should be stopped!!

One member I have messaged said she is taking both so we will get our GP to question this but I wondered if anyone else was either taking both or had any comments about this.

Thank you

3 Replies

Hi Nadine

I've just checked the info about Methotrexate. Whilst it mention Septrim it doesn't say not to take it, but it says your doctor will make necessary adjustments (or words to that effect) - see the last sentence below:

"Be sure to mention the medications listed in the IMPORTANT WARNING section and any of the following: certain antibiotics such as chloramphenicol (chloramycetin), penicillins, and tetracycylines; folic acid (available alone or as an ingredient in some multivitamins); other medications for rheumatoid arthritis; phenytoin (Dilantin); probenecid (Benemid); sulfonamides such as co-trimoxazole (Bactrim, Septra), sulfadiazine, sulfamethizole (Urobiotic), and sulfisoxazole (Gantrisin); and theophylline (Theochron, Theolair). Your doctor may need to change the doses of your medications or monitor you carefully for side effects."

Hope that helps.



I was also on both and had no side effects. Had regular blood tests. I think they have to balance up the risk of taking it or not taking it.


I have personally experienced this having just completed treatment for Burkitt's Lymphoma. MTX plus Septrim caused an ALT spike in my liver and threatened to reactivate my Hepatitis. On my last cycle, we withdrew Septrim one week before the start of MTX and the spike was avoided. If Septrim is only used for prophylaxis, I would go along with the doctor's recommendation. The risk of getting PCP was over ruled by the risk of reactivating HBV in my case.


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