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Will Your Antibiotic Interact with Your Blood Pressure Pill?

Taking the wrong antibiotic with an ACE inhibitor blood pressure medicine could lead to excess potassium, heart rhythm changes and death.
Will Your Antibiotic Interact with Your Blood Pressure Pill?
A woman struggling with all her medication

Before you start taking any new medicine, it makes sense to ask about potential interactions with the drugs you are already taking. It is a good thing one reader asked about potential interactions between blood pressure medication and an antibiotic. The combination could trigger lethal consequences.

Does the Antibiotic Bactrim Interact with Quinapril?

Q. Bactrim is the only antibiotic that works well for me. Would it interact with the quinapril I take for my blood pressure?

A. Please contact your physician and pharmacist immediately. The combination of an ACE inhibitor like quinapril or lisinopril with an antibiotic such as co-trimoxazole (Bactrim or Septra) could be life threatening (BMJ, Oct. 30, 2014).

ACE inhibitors can lead to increased potassium levels. (Here is a list of ACE inhibitors and a description of some serious side effects.) Usually people taking an ACE inhibitor for blood pressure don’t have to worry about excess potassium. But adding co-trimoxazole to the mix changes that completely.

Too Much Potassium!

With this combination, potassium can rise quickly and lead to cardiac arrest. Symptoms of this condition (hyperkalemia) include heart palpitations, nausea, tingling or numbness in the lips, feet or fingers, trouble breathing, fatigue, weakness, slow pulse and confusion. You can read more about this interaction and how to avoid other dangerous combinations here.

To learn more about ACE inhibitors like quinapril and other ways to control blood pressure, you may want to read our Guide to Blood Pressure Treatment.


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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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