Older woman taking blood pressure

One of the most commonly prescribed drugs in the world today is a diuretic called hydrochlorothiazide. That’s a mouthful. Not surprisingly, health professionals abbreviate this medication. It sometimes appears as HCTZ. That is sometimes shortened to HCT or HZT. It is often found in brand name blood pressure medications so a patient might not even realize she was taking HCTZ. Most physicians perceive this drug as super safe. They may not mention that HCTZ can raise blood sugar levels.

According to our calculations over 23 million Americans swallow HCTZ daily to control blood pressure or control fluid buildup. Most people assume that this diuretic has few, if any, side effects.

HCTZ and Potassium Problems:

If patients are warned about a potential problem it might be that hydrochlorothiazide can deplete the body of potassium. Advice may range from eat a banana and drink some orange juice to sprinkle your food with a salt substitute containing potassium chloride. What many people are not told is that HCTZ can raise blood sugar.

HCTZ CAN Raise Blood Sugar Levels:

Q. I took hydrochlorothiazide (HCTZ) for 14 years to control blood pressure. When I started, my blood sugar was completely normal. Within a few years it began to climb.

After my doctor doubled my HCTZ dose, my fasting blood sugar soared. No one ever warned me that diuretics could cause diabetes. Would changing my BP drug help me with my diabetes?

A. Many medications, including diuretics like HCTZ can raise blood sugar. That is NOT a message that is well received by some physicians.

Chastised by Doctors Who Reject Side Effects:

A couple of years ago Dr. E.B.M. responded to an article we wrote for our syndicated newspaper column titled: Do Common Medicines Trigger Diabetes.

Here is his outraged reaction:

“As a Board Certified Internist and Emergency Room physician for 21 years, I must reply to this. My mother sent me the link wondering if taking of lisinopril would also ‘trigger diabetes.’

“Please read the article I am attaching in its ENTIRETY to better understand the pros and cons of thiazide diuretics. Perhaps it will persuade the reader to not leap to the conclusions so irresponsibly presented on The People’s Pharmacy:

“Diuretic Treatment of Hypertension” (Diabetes Care, May, 2011)

“Joe and Terry, you are promoting dissent and insidiously advising patients to question the competence of their physicians with poor research examples and a lack of unbiased attention to the real data available. It’s embarrassing even reading what you have written on your website.

“And just to settle the issue:

“If a patient chooses not to take a medication because of a side-effect that ‘might’ happen, then you might as well take nothing. There’s no such thing as a harmless medication, be it herbal, ‘natural,’ or pharmaceutical. Medicines can harm and they can help. We, as physicians, deal with the ‘probable.’

“This is a fact of medicine. There ARE no absolutes. HCTZ will PROBABLY not cause you to get diabetes. Can’t say absolutely, but PROBABLY not. If you get diabetes on it, its far more likely you developed the diabetes for other reasons (as the article linked mentioned).

“Any physician worth his salt would certainly look to consider an alternative if necessary, but if the benefit of the HCTZ outweighs the risk, then the best choice MIGHT be to continue it. Perhaps the diabetes can be managed with the same diet that SHOULD have been present before the hypertension started….i.e. low sodium and low carb.”

People’s Pharmacy Response:

Ouch! That hurts. We responded to Dr. E.B.M. by asking why he didn’t reassure his mother that lisinopril was not a thiazide diuretic and does not raise blood sugar. That would have been the obvious answer. But Dr. E.B.M.’s reaction went way beyond the obvious.

We prefer not to get into arguments whenever possible. Our readers came to our defense:

Sal J. wrote in response to Dr. E. B. M.:

“In response to Dr. EBM, I in no way believe that the Graedons are ‘promoting dissent and insidiously advising patients to question the competence of their physicians.’ They simply are reporting a patient’s experience and that the diuretic HCTZ (hydrochlorothiazide) could have raised his blood sugar levels high enough to trigger a diagnosis of diabetes. [Here is a link to the original article]

“They are not telling people to abandon their medications (and never do) but simply to be aware of possible side effects causing diabetes, which are the exact same warnings enclosed with the inserts I receive in my losartan/HTZ and amlodipine prescriptions from the pharmacy.

“Pharmaceutical companies list the side effects they absolutely have to…no more. Most physicians have little information aside from what they’ve been told by their drug reps. I like to be in partnership with my internist specializing in geriatrics, but he does not keep up with recent studies so easily available to everyone, including doctors.

“When my blood glucose suddenly became elevated, I showed him recent studies (The Lancet, Archives of Internal Medicine and JAMA), revealing that women especially over age 50 taking statins could experience a significant risk of developing diabetes. He wouldn’t even read it saying, ‘It depends who you listen to.’ At the end of our meeting, he said, ‘I do have a doctorate.’

“I didn’t have high cholesterol but I do have uncontrollable risks for diabetes, so I took myself off my pravastatin, because I realize this drug I have taken for a long time could become a problem as I have gotten older (I am 74). He also prescribed levaquin (with a bold black box warning) to my husband who could hardly walk after only three of five tablets for bronchitis; our elderly neighbor ruptured his Achilles tendon while on long-term Cipro.

“With a now elevated blood glucose, I am looking into all areas for improving this situation including diet, exercise and medications since 96 percent of the nearly 26 million Americans with diabetes have type 2 diabetes and I don’t want it. In the meantime, I welcome further newsletters from the Graedons with their up-to-date messages and alerts.”

A different doctor (Michelle) agreed and disagreed with Dr. E.B.M.:

“I have had many patients on HCTZ and it can cause hyperglycemia [elevated blood sugar]. I have yet to see a patients develop diabetes from HCTZ after 30 yrs of practice.”

Another reader, H.J.L., offered this perspective:

“Sorry EBM, I think your attack on the Graedons was over the top. I don’t think you read every word of what the Graedons said.

“You may be the best emergency doc in the world, but you deal with patients on a short term basis. Managing long term care has its own set of requirements.There are many docs out there who are not good, who don’t keep up and don’t listen. For a doc to deny the possibility that a diuretic could cause onset diabetes is malpractice.

“Your mother acted reasonably asking you for help about her lisinipril. What’s the big deal? There is nothing non-factual in what the Graedons said. Besides the diabetes issue, they raise the fact that perhaps potassium supplementation should be explored.

“I read almost all of the article you cited and do not have the background to understand everything in it. But I found nothing in it that contradicts anything the Graedons said. In fact it supports it. This is a direct quote from the article you cited: (Note: NOD is new-onset diabetes):

“In conclusion, we should refrain from underestimating the adverse prognostic impact of NOD induced by diuretics and β-blockers, alone or combined, solely because of the failure by most randomized trials to disclose a significant association between NOD and outcome. NOD, whether or not induced by drugs, remains an important adverse prognostic marker that should be prevented. We suggested that in subjects at increased risk of NOD (impaired fasting glucose, obesity, metabolic syndrome), diuretics and β-blockers should 1) be used cautiously, with the lowest effective dose and plasma glucose periodically checked, and 2) be avoided in subjects with BP normalized by different classes of antihypertensive drugs.”

H.J.L. goes on to write:

“I am sorry your mother ‘bothered’ you with her reasonable question. But please read your own sources more carefully before you attack others who are completely factual. If I am wrong, cite one factual error in what the Graedons said.” [again, here is a link to the original article]

Another Reader Says HCTZ Can Raise Blood Sugar:

“I was prescribed hydrochlorothiazide by my previous doctor as an additional high blood pressure medicine. I took it for years.

“My previous doc never told me it would RAISE my blood sugar. Just before I changed doctors, I was diagnosed with type 2 diabetes.

“My new doctor took me off hydrochlorothiazide and changed me from the other high blood pressure med I was on. It was causing me a chronic cough which the former doctor never admitted was caused by my medicine!).

“MY ADVICE: Discuss with your doctor any possible drug side effects. If he has his head in the sand and refuses to discuss complications, FIND A NEW DOCTOR!”

The People’s Pharmacy Perspective:

In response to the original question we suggest that the person should ask the doctor about other options for controlling hypertension that will not elevate glucose levels.

To help with that conversation, we are sending you our Guides to Blood Pressure Treatment and Managing Diabetes. The latter lists many drugs that can boost blood sugar.

Anyone who would like printed copies, please send $6 in check or money order with a long (no. 10) stamped (70 cents), self-addressed envelope:

  • Graedons’ People’s Pharmacy, No. DMB-17
  • P. O. Box 52027
  • Durham, NC 27717-2027.

Hydrochlorothiazide is also found in medications like:

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

Share your own thoughts about HCT in the comment section below. Other side effects of hydrochlorothiazide include: low potassium levels, low sodium levels, low magnesium levels, low calcium levels, muscle cramps, high uric acid levels, elevated lipid levels, low blood pressure upon standing (orthostatic hypotension), dizziness, digestive distress (loss of appetite, diarrhea), erectile dysfunction, weakness, skin rash, kidney damage and blood disorders.

Such side effects may be rare, but we believe it is important for people to know what side effects to be alert for. If they do not occur, great! If they do occur, a conversation should occur with the prescriber. No one should ever stop any medication without discussing it with the prescribing physician!

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  1. Jackie

    I come from a family with a history of diabetes, high blood pressure, and women who have had heart attacks in their 50s. Hoping for a different scenario for myself. I regularly exercise and try to eat well. However, at 58, I am having BP creep steadily upward. Have been put on HCTZ (raised blood sugar to 5.9, then 6.1) and was taken off when sugar rose. HCTZ did, however, effectively lower my pressure. Other drugs: Amlodipine and various angiotensin receptor blockers have not been as effective, even in combination. Which beast should I serve: BP or diabetes? Used to be in 130s/80s, starting to see 140s/90. Am within BMI. Any advice?

  2. Gottlieb
    Green Bay

    After 3 months on Lorsartan HCT, my A1C status rose from “Non-Diabetic” to “Increased Risk” for diabetes.

    Had not been informed that the diuretic component HCT (Hydrochlorothiazide) can cause hyperglycemia resulting in the raised A1C.

    Asked for a different hypertension med that would not cause hyperglycemia. Was prescribed Amlodipine, but before picking it up, did my homework researching The People’s Pharmacy website and others and learned the doc was wrong. Amlodipine is just as likely to contribute to hyperglycemia.

    Asked that I instead be prescribed Losartan WITHOUT the Hydrochlorothiazide diuretic component, the likely cause of A1C rise. Doc agreed to 1-month trial to evaluate BPs and 3-month trial to evaluate A1C.

    Have already researched a new BP med if needed, Indapamide. Although I’m not too keen on the side effects (dizziness, constipation or diarrhea, drowsiness, headache, nausea, and more), I’m encouraged by the NIH stating the following:

    “Diuretics are among the first drugs offered to the hypertensive patient. … Indapamide is a diuretic and vasodilator that DOES NOT RAISE BLOOD GLUCOSE or lipid levels. We therefore investigated its use as a substitute diuretic in patients whose treatment had resulted in hyperglycemia and/or hyperlipidemia.”

  3. Dorothy

    I was put on HCTZ for prehypertension by a dr. I took it for years! I got constant belly aches that eventually became so severe I sought medical attention from a gastroenterologist. I had a CT scan and MRI to find that I had an extremely dilated bial duct and finding was past pancreatitis…. I don’t drink very much alcohol but was constantly asked if I did. After much of my own research I found that thyzide drugs cause pancreatitis.

    Oh, and do I mention that the pancreatic enzymes in my blood were 5 times what is normal. As soon as I took myself off of the HCTZ everything went back to normal. Ummm and did I also fail to mention that no doctor would actually admit to me that the HCTZ caused the pancreatitis. Although my primary dr has a note in my chart that I “may” be allergic to it. Just thought I’d share

  4. Denise

    In my early fifties, my doctor put me on HCTZ for what she called essential hypertension. I took a 25 mg dose for four days and by the fourth day was experiencing a racing heart (125 bpm when I was reading the newspaper), felt awful, was tired and dizzy. I called to ask about these side effects and was told by a nurse that she did not see them listed on her info. I told her I read about them in the info from the pharmacy.

    Later the nurse called me to tell me the doc would switch me to a Beta blocker. I said no thanks – since I have mild asthma – beta blockers are not recommended for asthmatics. Instead I began walking more, eating better, and lost some weight. However, my blood pressure may have been high due to the hyperparathyroidism that was discovered by my new PCP about 8 years later. Since I had surgery to correct it, my blood pressure has been back to the 100’s/60’s to 110’s/70’s that it had been when I was younger. So the extra calcium in my blood from the hyperparathyroidism seems to have been at the root of high blood pressure for me.

  5. Wendy
    Central Florida

    I take this particular medication and I believe it helps keep my blood sugar levels up, at least it is my experience. Doctor’s don’t always tell you everything and a lot of times, they may not even know about side effects themselves. It pays to take a proactive approach to medications and research. I appreciate the Graedon’s articles and I also like to read feedback about what others are saying about a particular medication. Keep up the good work!

  6. Virginia

    As a person who is VERY intolerant of most medications, I can tell you for certain that most doctors do not believe that any thing they order for a patient could cause any problems. And honestly even good ones don’t always remember that “ah, you’re that patient” so remind them whenever something new is prescribed, even if you feel like a nag. It’s you who pays the price!

  7. Lynne

    One of your readers said that her husband “could hardly walk” after taking a med with HZT. How does this effect walking? I take losartan & have trouble walking & nothing shows on an MRI as to the cause of pain. Is there any relationship between HZT & pain in lower back?

    • Marla

      I believe the husband of reader you’re referring to was prescribed Levaquin (an antibiotic) not a diuretic. I took her comment to mean that the doctor in question would not have acknowledged the pain which is associated with fluoroquinolone antibiotics (such as Levaquin).

  8. Tony

    I was on HCTZ for more than 10 yrs, and suffering thru many episodes of gout, before I discovered that the HCTZ raised my Uric Acid levels….
    I discussed this with my Internist, and he said he could put me on Allopurinol or take me off of the HCTZ….I chose the latter…
    My gout episodes have greatly diminished because of it…

  9. Phil

    So, am I supposed to be impressed by an “A”hole Doctor who has a Doctorate? (which is probably w-a-y out of date? Sorry, I’m not. I’m a firm believer in continuing education, even from those of us who are below our station in life!

  10. Angela

    I have said many times: the drug industry is killing us. The Food industry is killing us. The Medical industry is killing us.

  11. John
    Rock Hill SC29732

    My wife had a skin rash for years. She finally discovered she was allergic to the sulfa moeity in the compound. Oh, the multiple doctor visits and the trips to the pharmacy for various creams and lotions that were prescribed.

  12. Pat

    I am sensitive to anticholinergics. When I discovered that HCTZ was an anticholinergic I asked my doctor to order just the Losartan w/o HCTZ. He was not aware that it was anticholinergic but looked it up and then agreed. I am post menopausal and don’t retain fluid as I did in the past. My blood pressure is stable.

    I did have quite a fight to get off of Lisinopril when I started having disruptive coughs several years ago. Despite the fact that Lisinopril cough is all over the literature many MD’s seem unaware. Other BP meds also caused a cough but the Losartan has been great.

    I wish it was easier to access full articles from medical literature. It is best to go in prepared when you have a concern.

  13. Fran

    Are those medications mentionned, prescribed for cholesterol or for hypertension ? also statins ?

  14. George
    Chapel Hill, NC

    Dear Joe and Terry,

    My ENT doctor prescribed Hydrochlorothiazide (which I can now pronounce like a champ) for Meniere’s disease in order to control my tinnitus and I think it helps. My blood sugar is high but I don’t know if is a result of my food addiction or Hydrochlorothiazide. If you know of any other drug for Meniere’s disease, let me know!

    — ge

  15. Muriel
    Durham NC

    I too was disparaged by my primary doctor over side effects of HZTC. My cholesterol began to rise with no great changes in my eating habits and despite my planned weight loss. The next affront was a Rx for cholesterol lowering meds which I did not take. When I mentioned that this was one of the side effects of HZTC listed on the packaging and that I had read up on it on the internet, the doctor flew into something of a mini rage. Never mind that the HZTC prescription had to be cut down by a 3/4 to a 1/4 dose and I was experiencing dizziness at the original dosage amount. I reduced my cholesterol by taking fish oil and lecithin and by reducing shell fish consumption.

  16. Marian

    Huge question hanging over this discussion: if blood sugar levels rise, is this irreversible? Does changing medication provide some chance of reversing BS levels?

    • Terry Graedon

      It should be reversible, at least up to a point. After years of taking the drug, the elevated blood sugar might not be reversible upon stopping.

  17. Jill

    This med made me sicker than anything. It was prescribed to help control my slowly raising blood pressure. Within a week my body just ached and hurt all over. My joints, all of them, felt painful. I told my reg doc how much my body hurt since taking this med prescribed by a heart doctor. She suggested that I go off the medication and find a more natural way to help me get my blood pressure to a better level.

    It was alarming to feel my body go downhill so quickly. I revived within a few weeks from the painful joints and body aches.

What Do You Think?

We invite you to share your thoughts with others, but remember that our comment section is a public forum. Please do not use your full first and last name if you want to keep details of your medical history anonymous. A first name and last initial or a pseudonym is acceptable. Advice from other commenters on this website is not a substitute for medical attention. Do not stop any medicine without checking with the prescriber. Stopping medication suddenly could result in serious harm. We expect comments to be civil in tone and language. By commenting, you agree to abide by our commenting policy and website terms & conditions. Comments that do not follow these policies will not be posted.

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