Septra and Aldactone Combo May Increase Hyperkalemia Risk, Group Warns

A consumer watchdog organization is warning the elderly to avoid the antibiotic, Septra, and the diuretic, Aldactone, due to a potential increased risk of experiencing dangerously high levels of potassium in the blood. 

In the December issue of Public Citizen’s Worst Pills Best Pills newsletter, the prominent consumer group points to recent medical studies that suggest Septra and Aldactone are linked to a condition known as hyperkalemia, high potassium, which can cause a number of health problems. The group warns that using the two drugs in combination greatly increases the risks and dangers of hyperkalemia.

Hyperkalemia often occurs with no symptoms, but can cause irregular heartbeat, nausea, changes in breathing pattern, loss of consciousness, weakness or a slow, weak pulse or a pulse that cannot be detected. The elderly are particularly at risk for hyperkalemia because their kidneys have a more difficult time filtering excess potassium out of the blood.

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In September, a study was published in the British Medical Journal (BMJ) in which researchers looked at elderly patients who were on Aldactone and were then given antibiotics to treat a urinary tract infection. They found that a combination of Aldactone and Septra increased the risk of hyperkalemia more than 12 times; much higher than Aldactone combined with any other antibiotic.

Public Citizen warns that patients should let their physician know they are on Aldactone if they are being treated for a urinary tract infection and make sure their health care provider is aware of the potential risks of combining the two drugs. They also warn patients to be aware of the potential symptoms if they are on the two drugs or any drugs that increase potassium blood levels, and to seek immediate medical attention if the symptoms occur.

Aldactone (spironolactone) was approved by the FDA in 1985 as a diuretic. Originally manufactured by Pfizer, it is available as a generic.

Septra (sulfamethoxazole and trimethoprim; also known as cotrimoxazole) was approved as an antibiotic by the FDA in 1973 and is widely available as a generic. The brand name versions, Septra and Septra DS, are distrubited by Monarch Pharmaceuticals, a division of King Pharmaceuticals.


  • KathyAugust 14, 2019 at 12:25 am

    I took bactim. I had irregular heartbeat and hard breathing walking to bathroom. I fell 2 times ending up in icu and am going to have rehab due to i cant walk by myself. My leg muscles are real weak and painful. One fall dislocated my elbow while dr. Was fixing it i almost died becsuse oxygen level dropped.

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