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. Diane

    I take enalapril 10/25mg HCTZ. I developed many skin problems–including a wart on the top of my breast. This RX also caused pain n my right knee, left elbow, foot and now gout at the base of my right toe. I am eating the correct diet to help eliminate the gout. It’s better but still lingers!

  2. MIke

    My husband was given hydrochlorothiazide when it was discovered he had high blood pressure…he also had another problem at the time with a diverticulitis attack that ruptured his intestine and needed immediate attention as well as 2 surgeries and a long recovery. He started back to work after being off for 2 months and almost immediately started in with gout attacks. He suffered from Gout a few years before this but changed his diet and lost 70 lbs and no longer had any problems, until the past few weeks. This past week he got to the point where every joint from his knuckles in both hands, wrists, knees, ankles, elbows. It was horrific! I got him in with his doctor and right away the doctor questioned who put him on the hydrochlorothiazide….we couldn’t believe it…this very doctor did! So come to find out hydrochlorothiazide can cause gout. So all this suffering and missed work was put on my husband when this doctor knew my husband had a history of gout!

  3. Jill C

    I’ve been on HCTZ for about 20 years. I was advised that it would increase my sensitivity to the effects of the sun–sunburn and eye sensitivity to light. Although I haven’t had problems with sunburn (what with the typically cloudy weather we enjoy in western Oregon), I have noticed over the past several years increasing sensitivity to glare from headlights while driving at night. I suspect this little-known side effect may be a common cause for many motorist’s discomfort or inability to drive at night.

  4. MARY

    I took low dosage HCTZ for at least 20 yrs for high BP w/other BP meds. just this year i have had edema in ankles and legs and could not fit in my regular shoes for most of this year.

    It must be the combination of drugs that I now take that has caused this change because I stopped taking HCTZ just a day or two and already the painful swollen edema is subsiding. Replaced it w/another low dose diuretic for now. I am 87 Yrs old.

  5. Peggy

    I’d been off HCTZ for a while but started back (It’s prescribed for fluid retention.) This time around I had horrible cramps. Usually magnesium gel calmed them down but sometimes I had to soak in a bathtub of hot water before I could get to sleep.

  6. Dave
    Madison, WI

    How about tinnitus as a side affect?

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