The need-to-know information about TMP-SMZ (Septra)


Pearls and fun nuggets

1. TMP-SMZ may not be the most friendly 😒 Because it has a higher incidence of adverse effects, including allergic responses, its use has been restricted in many countries to very specific circumstances where its improved efficacy has been demonstrated.[8]

2. TMP and SMZ are best when they work together 👫  TMP alone is only bacteriostatic (inhibits growth), but adding SMZ makes it bacteriocidal (kills bacteria). 

3. TMP-SMZ is a 1 to 5 ratio ➗  It consists of one part trimethoprim to five parts sulfamethoxazole.[2]

4. It’s a fairly old drug 🎩The synergy between trimethoprim and sulfamethoxazole was first described in the late 1960s.[24][25][26] Trimethoprim and sulfamethoxazole have a greater effect when given together than when given separately, because they inhibit successive steps in the folate synthesis pathway.

Patient Perspectives

“This medication makes me extremely tired and causes headaches but it seems to be working where other antibiotic treatments have failed to cure my infection. If you are able to tolerate the side effects it’s has been a pretty good therapy for me.”


“This has cured my MRSA 5 times now. It is the only thing that works for me.”


“This medicine caused vomiting for me, whether my stomach was empty or not. I wish I could tolerate it, because it’s a good treatment, but for those who are sensitive, this is not a good medicine.”

Brandon Simpson, PA-C
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