home blood pressure monitor, lower blood pressure

We suspect that hydrochlorothiazide (HCTZ or HCT for short) is the most prescribed drug in America on a daily basis. HCTZ is taken regularly by over 20 million people. More than 115 million prescriptions are dispensed annually.

Many doctors believe that hydrochlorothiazide (HCTZ) side effects are mild and rare. Patients are not always warned about adverse drug reactions.

We think people need to know more about this widely prescribed diuretic and blood pressure medicine.

Hydrochlorothiazide (HCTZ) Side Effects:

Electrolyte Imbalances:

  • Low potassium levels (hypokalemia)
  • Low sodium levels (hyponatremia)
  • Low magnesium levels (hypomagnesemia)
  • High calcium levels (hypercalcemia)
  • Low chloride levels (hypochloremia)
  • Low zinc levels

Other Hydrochlorothiazide (HCTZ) Side Effects:

  • High blood sugar levels (increased risk of type 2 diabetes)
  • High uric acid levels (increased risk of gout)
  • Elevated blood fats & cholesterol
  • Low blood pressure (leading to dizziness, lightheadedness on standing, fainting)
  • Digestive upset (stomach ache, diarrhea)
  • Muscle cramps, muscle weakness
  • Dry eyes
  • Headache
  • Sensitivity to sunlight, sunburn, rash
  • Erectile dysfunction, impotence
  • Irregular heart rhythms
  • Severe skin reactions (requires immediate emergency attention), dangerous allergic reactions
  • Blood disorders
  • Liver or kidney problems

Zombified by Too Many Side Effects:

Most people zone out after seeing just a few of the many listed hydrochlorothiazide (HCTZ) side effects. They assume that such complications will never affect them. Our bulletin boards and comments would suggest otherwise. The only way to truly grasp the meaning of such hydrochlorothiazide (HCTZ) side effects is to read stories from real people.

Let’s start with just one of these adverse reactions: high uric acid levels aka hyperuricemia.

Gout and HCTZ:

Q. I was on HCTZ to control my blood pressure for more than ten years. I suffered through many episodes of gout before I discovered that HCTZ raises uric acid levels.

I discussed this with my Internist, who said he could put me on allopurinol or take me off the HCTZ. I chose the latter, and my gout episodes have greatly diminished.

A. Gout is an excruciating inflammation of one or more joints linked to high uric acid levels. Diuretics like HCTZ (hydrochlorothiazide) can indeed raise uric acid levels. Such medicines are often prescribed to lower blood pressure.

Other readers have also experienced gout after taking HCTZ:

Tony in Florida says:

“I took HCTZ for about 15 years to lower my High BP. Soon after I started taking it, I started getting episodes of gout. Belatedly, I finally put the pieces together that HCTZ was a major contributor to my gout.

Blood Sugar Elevations and Diabetes:

We got spanked a few years ago by an outraged physician. He was furious because we wrote that diuretics like HCTZ could raise blood sugar and sometimes trigger type 2 diabetes. He considered our answer to a reader’s question “thoroughly irresponsible.”

You can read the whole story at this link:

Do Common Medicines Trigger Diabetes?

We’re not sure why this doctor was so upset. The FDA requires manufacturers of thiazide diuretics like HCTZ to state in the official prescribing information that:

“In diabetic patients dosage adjustments of insulin or oral hypoglycemic [diabetes] agents may be required. Hyperglycemia [diabetes] may occur with thiazide
 diuretics. Thus latent diabetes mellitus may become manifest during thiazide therapy.”

Reports from Readers:

Chuck says:

“I have been on HCTZ for 14 years. When I started my blood sugar was completely normal, but shortly after I went into the pre-diabetic range.

“Fasting blood glucose [FBG] was in the 105 to 115 range for more than 12 years, then 18 months ago my physician doubled my HCTZ dosage from 12.5mg to 25mg, and 12 months ago I was diagnosed with diabetes (FBG of 151).

“The kicker is that not one of these physicians ever informed me that there was a risk that HCTZ could cause an increase in blood sugar, and after it became full blown diabetes not one has suggested a change in my blood pressure medication.

“I feel it is the responsibility of the prescribing physician to discuss with me all of the potential side effects, and we will make the decision together. In my case several physicians felt “they knew best” and decided for me. This is unethical, but unfortunately seems to be the norm for some in the medical community.”

Brian added this:

“What a surprise I have been have been struggling with blood sugar levels myself. I also take hydrochlorothazide). In addition, I was suffering foot pain, even though the test for gout was negative my Dr suggested Indomethacin. This website provided information about problems HCTZ can cause. What a relief to know more about side effects of this medicine.”

Angela also reported early problems with HCTZ:

“I’m taking HCTZ for high blood pressure. I’m 78 and pretty healthy and have been on the pill since 5/07. Because I come from a diabetic family, I always have my glucose checked with my cholesterol. This month, for the first time, my glucose was 113; high for me and worrisome.”

HCTZ and Cholesterol:

Muriel in Durham, North Carolina shared this story:

“I was disparaged by my primary doctor over side effects of HCTZ. My cholesterol began to rise with no great changes in my eating habits and despite my planned weight loss.

“When I mentioned that this was one of the side effects of HCTZ listed on the packaging and that I had read up on it on the internet, the doctor flew into something of a mini rage. I was also experiencing dizziness. I reduced my cholesterol by taking fish oil and lecithin.”

Hydrochlorothiazide (HCTZ) Side Effects & Electrolyte Imbalances:

Even if people are warned about mineral imbalances with thiazide diuretics like HCTZ they may not appreciate how dangerous this can be.

Low Sodium and Potassium:

This past summer we received the following question from a concerned daughter:

“My elderly mother has been very conscientious about a low-salt diet. She never salts her food and is careful not to eat processed foods high in sodium. Despite this, her doctor diagnosed her with mild high blood pressure and put her on a diuretic called hydrochlorothiazide.

“Last week she got up in the middle of the night to go to the bathroom. She suddenly felt weak and collapsed. When the paramedics came in response to her call button, she was confused.
They took her to the hospital and discovered that her sodium and potassium levels were perilously low. Could her medicine be responsible for this scary episode?”

Diuretics like HCTZ can deplete the body of critical minerals. That includes potassium, sodium, magnesium and zinc. When these electrolytes get out of whack it can be very dangerous.

Liz in Raleign, NC dodged a bullet with her diuretic-induced hyponatremia:

“I was in my neighbor’s yard around dusk to check on his cat. I fell on something and hit my head, ending up in the trauma intensive care unit for four days. I needed four staples in my head to close the cut.

“I had limited memory before I fell and no memory at all for about three days while in the hospital. The diagnosis: low sodium. Mine was 116. The normal range is 136-145. I had no noticeable signs before I fell that anything was wrong.”
Hyponatremia is diagnosed when sodium levels fall below 135 mEq/L.

Priscilla in SC didn’t get a definitive diagnosis, but…

“I have used HCTZ for several years; did have infrequent muscle spasms in the lower legs, frequent urination, bladder incontinence. Quite recently I suffered a fainting spell, with accompanying dizziness and shakiness. I am presently under a cardiologist’s care after three days of hospitalization. Doctor suspects HCTZ but haven’t decided on clear diagnosis.”

The New BP Guidelines:

The American Heart Association and the American College of Cardiology have determined that all Americans should get their blood pressure to 130/80 or lower. That means that nearly half of all adults in the United states (103 million people) will be exhorted to lower their BP. And that means lots more prescriptions for diuretics.

Most people can tolerate diuretics like hydrochlorothiazides without problems. If such drugs work to control blood pressure without side effects, that is fabulous!

But we fear that many people will not be told about hydrochlorothiazide (HCTZ) side effects. They may not be monitored for sodium, magnesium, potassium or zinc on a regular basis.

Perhaps even more disturbing, many people won’t even realize they are taking a thiazide diuretic. That’s because it is often tacked on the end of the name of the BP medicine as HCT or HCTZ without much explanation or warning about adverse drug reactions.

Drugs Containing Hydrochlorothiazide:

  • Atacand HCT
  • benazepril HCTZ
  • Benicar HCT
  • bisoprolol HCTZ
  • candesartan HCTZ
  • captopril/HCT
  • Diovan HCT
  • enalapril HCT
  • eprosartan HCT
  • Exforge HCT
  • fosinopril HCT
  • hydrazine HCT
  • lisinopril HCTZ
  • Lopressor HCT
  • losartan HCTZ
  • metoprolol HCT
  • Micardis HCT
  • moexipril HCT
  • Monopril HCT
  • olmesartanHCT
  • propranolol HCT
  • quinapril HCT
  • spironolactone HCT
  • Tekturna HCT
  • telmisartan HCT
  • Teveten HCT
  • triamterene HCTZ
  • valsartan HCT

The People’s Pharmacy Perspective:

Diuretics like HCTZ are generally inexpensive. They lower blood pressure and can help control fluid build up (edema). Side effects are not as serious as with some other BP meds. But patients must be told about problems like dizziness, electrolyte imbalances and some of the potential complications like gout. Frequent blood tests are essential to make sure minerals like magnesium, sodium and potassium are not creeping into the danger zone. No one should stop this medication (or any other) without careful consultation with the prescribing physician. If hydrochlorothiazide (HCTZ) side effects become troublesome, however, doctors have a number of other options for treating elevated blood pressure.

Share your own story about diuretics in the comment section below. We want to hear success stories as well as tales of woe and intrigue.

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  1. 1Understanding Ayurvedic Medical Practice and Professional Standards
  2. 2Show 1101: How You Can Use Essential Oils for Better Health
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  5. 5Baby Boomers Less Likely to Have AMD
  6. 6Low Dose Naltrexone (LDN) Provides Surprising Pain Relief
  7. 7Coffee Drinkers Lower Their Chances of Heart Failure
  8. 8Do You Want Digital Pills to Report When You Take Them?
  9. 9Hydrochlorothiazide (HCTZ) Side Effects, Complications and Gout!
  10. 10Do You Have High Blood Pressure?
  11. 11How Dangerous Is It to Stop Taking Aspirin?
  12. 12An Inside Look at Pharmacy Mistakes

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  1. Linda
    New York

    Muscle Cramps doesn’t begin to describe my ordeal. I literally dropped to the floor in agony, was unable to straighten my legs and crawled to get a heat pad and Mustard. It was almost a daily episode. I finally quit the HCTZ and substituted Dandelion extract capsules and have been doing great with my B/P readings. I had also been taking amlodipine and have continued with that.

  2. Cindi

    I took this diuretic for ten years. It took a toll on my skin and eyes.

  3. Momtotut
    Georgia, USA

    HCTZ was prescribed for me because of my HBP, which at times is over 200. After a few days I was barely able to walk or even lift much more than a newspaper. Stand for any length of time was impossible. I knew it had to be one of the newly prescribed BP meds. Research indicated that HCTZ was the most likely one. My doctor reluctantly prescribed something else. It only took a few days for the worst of the weakness to go away. Thank goodness for your articles and the Internet!

  4. Anne

    I took HCTZ briefly and became so agitated I wanted to throw a chair through the window. I stopped taking it immediately, calling the doctor’s nurse to tell her so. My good physician said she’d not prescribe a diuretic for me again.

  5. Rosie

    I was in the hospital for low sodium (108) about 19 months ago. The hydrocholorithiazide was eliminated from my medications for several months. Now I am allowed 1/2 pill (12.5). Especially when I was off the drug and still now, my ankles/legs swell to the point of being very uncomfortable! What can I do to prevent this? My blood pressure is generally well controlled, but I hate the swollen legs!

  6. Kent H

    I stopped taking HCT because I was getting painful cramps beneath my rib cage. The doctor suggested that I needed to replace the electrolytes I was losing because of my blood pressure med lisinopril along with HCTZ. I took it one step further and stopped taking hydrochlorothiazide all together. My cramps are gone.

  7. Anandhi

    My mother was on HCTZ for mild elevated blood pressure about 10 years ago. After she was on it for about 2 weeks and had no warning about the severity of the side effects, she went on vacation and was out in the sun during the normal course of walking around–no sunbathing on the beach!

    She got severely sunburned on her upper chest, above where her shirt’s neckline, was and it took about 6 months and many visits to a dermatologist to finally get her skin back to normal. Of course, when we told her cardiologist on our next visit, said she had never heard of such a side effect but said there was no need for her to really be on HCTZ because she did not have edema.

    This confounded us as to why she prescribed something to begin, with if it was not necessary, and there were better alternatives. My mother has been on Norvasc since then with no side effects, other than mild dry mouth.

  8. Wendy Feen

    I have ended up in the ED more than once having to have a bolus of potassium due to HCTZ. I’ve had labile genetic hypertension for over 30 years so have always been prescribed something in addition to my angiotensin receptor blocker medication. Once the HCTZ was changed to Chlorthalidone I’ve had no issues with low potassium.

  9. Fay
    Raleigh, NC

    Thank you so much for writing in such detail about this critical information. It is so important that we learn about this and heed the warning’s and precautions.

  10. Lakshmi K.

    I was prescribed Hydrochlorothiazide for hypertension. It seemed to work for a while. Then the dosage had to be increased for better control. Then i developed sensitivity to sun !ight. Terrible itching and very bad skin rashes. I did some research and ruled out other meds did not cause this and only HCT was the cause. Discontinuing it stopped the skin reaction.

    My doctor never connected HCT with this condition.

  11. Carol
    Duluth, MN

    My mother was prescribed HCTZ for years. Her potassium and sodium levels had not been tested in three years, although she saw doctor for yearly checkups. At around 82 years old, she ended up in hospital for three days due incredibly low sodium levels.

    At the time, the area was in a very hot heat wave with very high temperatures and humidity. No air conditioning. She was sweating and drinking more water to stay hydrated. All of this worked together to cause the incredibly low sodium and potassium levels.

    Her hands were beginning to shake. We were lucky she did have a seizure, or die. Her blood pressure medications were changed while she was in the hospital, taking her off HCTZ.

  12. Robert Godwin

    I think would only be fair to list the incidence percentage of the side effects listed herein. HCTZ has proven efficacy as first line treatment for hypertension (e.h. ALL HAT trial). The fact of the matter is, all drugs have “potential” side effects, including natural products. Does the benefit outweigh the risk? That’s the question the clinician must answer.

    • Joe Graedon

      Hello Robert. May we assume you are a physician?

      There is no question that HCTZ does help control high blood pressure. If you check the ALLHAT trial I think you will find that they used chlorthalidone, not HCTZ. Although many health professionals think of chlorthalidone as a thiazide-like diuretic it is actually quite unique. One cannot generalize.

      We completely agree with you that “all drugs have ‘potential’ side effects, including natural products.” The point of our article is not to demonize thiazide diuretics but to point out that they can, on occasion, cause serious complications.

      Patients need to be warned about symptoms to be alert for. They also need to be tested regularly for electrolyte imbalances. A potassium, sodium or magnesium deficiency can sneak up on a patient without a lot of warning signs. If you are indeed a physician you know that hypokalemia, hypomagnesemia, or hyponatremia are very very dangerous.

  13. gw
    So Cal

    How can one evaluate the risk of taking an HCTZ if the numerical risk of developing one (or more) of these side effects is not known? My doctor thinks that these side effects are very rare – are there studies that show otherwise?

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