Go Ad-Free
logoThe People's Perspective on Medicine

Diuretic Blood Pressure Pill Could Send Potassium Way Too Low

The diuretic chlorthalidone taken to control blood pressure drove blood levels of potassium way too low, a risky situation.

Blood pressure medications are supposed to lower blood pressure. Some, however, also lower certain crucial minerals. What happens when a water pill makes potassium way too low? This can be a life-threatening emergency.

Diuretic Dropped Potassium Way Too Low:

Q. I had a bad reaction to my blood pressure medicines, amlodipine and chlorthalidone. I saw my PCP at the end of 2022 for a routine checkup and bloodwork. At that time, I asked about my potassium level, as I know certain blood pressure medications can deplete it. She said it was “low normal” and told me to eat an extra banana.

Jump forward to February 2023. I started feeling ill; my heart was racing, and I had numbness in my hands and felt like I might pass out. I thought I was having a heart attack, so my husband took me to urgent care.

They did not find anything but sent me to the emergency department. After more EKGs and lab tests, a doctor finally told me that my potassium level had dropped dangerously low. They gave me two intravenous potassium drips.

After a night in the hospital for observation, they let me go home with instructions to quit taking the chlorthalidone. I’m glad I survived, but doctors should be more aware of the side effects of medications they prescribe.

Consequences of Low Potassium Levels:

A. Low potassium levels can trigger life-threatening heart rhythm changes. Other symptoms include confusion and weakness as well as numbness or tingling and muscle spasms or cramps. Constipation, frequent urination and thirst may also occur.

Diuretics like chlorthalidone or hydrochlorothiazide can deplete the body of potassium, magnesium and even sodium. (We’ve written about low sodium here.) Chlorthalidone is more than twice as likely as hydrochlorothiazide to lead to hypokalemia (JAMA Internal Medicine, April 1, 2020).

Perhaps your doctor was not paying close enough attention to this possibility. The advice to eat an extra banana might not counteract a potentially dangerous potassium imbalance. With potassium way too low, diet is often inadequate. Moreover, many foods are richer in potassium than bananas.

In your case, amlodipine was an innocent bystander. You were smart to identify both medications you were taking to determine which might have been causing the problem.

Learn More:

You can learn more about blood pressure medicines in our eGuide to Blood Pressure Solutions.  In it we discuss a range of drugs, including potassium-sparing diuretics and drugs like lisinopril. These may sometimes lead to the opposite problem of too much potassium in the system. That can be just as serious.

You might wish to listen to our podcast on nondrug treatment of hypertension. It is Show 1134: Can You Control Your Blood Pressure Without Drugs?

Rate this article
4.7- 63 ratings
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..
Tired of the ads on our website?

Now you can browse our website completely ad-free for just $5 / month. Stay up to date on breaking health news and support our work without the distraction of advertisements.

Browse our website ad-free
  • Hripcsak G et al, "Comparison of cardiovascular and safety outcomes of chlorthalidone vs hydrochlorothiazide to treat hypertension." JAMA Internal Medicine, April 1, 2020. DOI: 10.1001/jamainternmed.2019.7454
Join over 150,000 Subscribers at The People's Pharmacy

We're empowering you to make wise decisions about your own health, by providing you with essential health information about both medical and alternative treatment options.