poison pill bottle

When doctors prescribe blood pressure medication, their goal is to reduce the likelihood that a patient with hypertension will develop heart attacks, strokes, kidney damage, eye problems or even Alzheimer’s disease. But some commonly prescribed blood pressure drugs can interact in dangerous, if not deadly, ways with other anti-hypertensive meds or even with antibiotics.

It is not uncommon for health professionals to prescribe two or even three different blood pressure medications to get a patient closer to “normal.” By the way, there is growing evidence that aggressively lowering systolic blood pressure (below 128) with medications in older patients  may actually increase the risk for cognitive decline (more about this here).

ARBs and ACEIs: A Dangerous Blood Pressure Mix

Our greater concern is the discovery that certain blood pressure medications may not play well together. Two of the most popular categories of blood pressure medicines are angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). They both belong to what is called RAS (Renin-Angiotensin System) inhibitors.

At last count more than 160 million prescriptions are filled annually for ACE inhibitor-type drugs. They include benazepril, captopril, enalapril, fosinopril, lisinopril, moexipril, perindopril, quinapril, ramipril and trandolapril. If there is a “PRIL” in the name, you can pretty much assume you are taking an ACE inhibitor.

ARBs include medications such as azilsartan, candesartan, irbesartan, losartan, olmesartan, telmisartan and valsartan. If there is a “SARTAN” in the name, you can pretty much assume you are taking an ARB. Over 80 million prescriptions are written annually for ARBs. While most of the ACE inhibitors are now available generically, that is not true for the ARBs. A minority are available in generic form at this time. Brand names like Atacand, Avapro, Azor, Benicar, Diovan, Exforge, Micardis and Teveten may be more easily recognized than their generic equivalents.

Taken independently, ACE inhibitors or ARBs are reasonably safe and quite effective for controlling high blood pressure. When these categories are combined, however, there can be serious complications. A review of 33 randomized controlled trials in (BMJ, Jan 28, 2013) comparing treatment with one single blood pressure medication to “dual blockade” with both an ARB and an ACE inhibitor together revealed some scary results.

The combination therapy led to an increased risk of a potentially life-threatening condition called hyperkalemia (excessive potassium levels). Too much potassium can lead to cardiac arrest. Other adverse reactions associated with dual therapy included hypotension (very low blood pressure) and kidney failure.

How Serious Are These Side Effects?

When your blood pressure drops too low you can become dizzy and fall. When an older person falls, it can lead to broken bones. A hip fracture is associated not only with disability but also death.

Kidney failure is another life-threatening condition associated with the combination of ACE inhibitors and ARBs.

The conclusion of the researchers was:

“Although dual blockade of the renin-angiotensin system may have seemingly beneficial effects on certain surrogate endpoints, it failed to reduce mortality and was associated with an excessive risk of adverse events such as hyperkalaemia, hypotension, and renal failure when compared with monotherapy. The overall risk to benefit ratio argues against the use of dual therapy.”

Despite this strong admonition to avoid combining ACE inhibitors with ARBs, it is estimated that over one million people are taking the two categories simultaneously. That may be because the FDA does not have a strong warning on the label of such drugs. The advocacy group Public Citizen has petitioned the FDA to include a black box warning about this problem, but to date the FDA has ignored this request.

Public Citizen also warns that the blood pressure drug aliskiren (Tekturna) should not be combined with either ACE inhibitors or ARBs for the same reasons: hyperkalemia, hypotension and kidney failure.

If you are taking an ARB together with an ACE inhibitor or with aliskiren please do NOT stop any drug suddenly. You can make a copy of the BMJ article and give it to your physician for consideration. Hopefully the data in the article will be convincing enough for the prescriber to reevaluate this combination.

Another Potentially Deadly Combination: Antibiotics and ACEIs or ARBS

We have been warning visitors to this website for years that the antibiotic co-trimoxazole (trimethoprim plus sulfamethoxazole, aka Bactrim or Septra and often abbreviated TMP-SMX or TMP-SMZ) could produce a life-threatening reaction if combined with an ARB or an ACEi. This is especially problematic for older people. Despite our efforts and FDA warnings, people continue to die from this combination.

Canadian researchers reported in BMJ (Oct. 30, 2014) that combining an ACE inhibitor or an ARB with co-trimoxazole “is associated with an increased risk of sudden death. Unrecognized severe hyperkalemia may underlie this finding. When appropriate, alternative antibiotics should be considered in such patients.”

These investigators go on to explain that the combination of an ARB or ACEi with the antibiotic co-trimoxazole can lead to very high levels of potassium, which in turn can cause irregular heart rhythms, cardiac arrest and death.

There are more details about this deadly drug interaction at this link.

How To Protect Against Dangerous Drug Combinations

You may be asking yourself how such interactions can occur if they have been thoroughly described in the medical literature. The answer is that busy physicians don’t always check for dangerous drug interactions. They may be harried or preoccupied and when an alert shows up on their smart phone or computer they often override it. Pharmacists are in the same situation.

If you find this hard to believe, you will want to read the chapter titled “Drug Interactions Can Be Deadly” in our book, Top Screwups Doctors Make and How to Avoid Them. You will also find our “Top 11 Tips for Preventing Dangerous Drug Interactions” at the end of the chapter. Although there is much more information in the book, here are the headings:

  1. Take a list of all your medicines to your appointment.
  2. Find out how to take your medicine!
  3. Check about whether any foods or beverages should be avoided.
  4. Ask your doctor to check for interactions. Before you leave the office, verify that your physician has reviewed your entire list of drugs and dietary supplements to make sure there are no incompatible combinations.

    If your doctor is using a computer or handheld device to submit your prescription electronically, ask if there are any drug interaction alerts that you should know about.

  5. Ask your pharmacist to check for interactions. Do not grab and go when you pick up your prescription.
  6. Inquire about over- the- counter drugs.
  7. Go to the Web to check on interactions yourself. The best resource we know of is MediGuard.org.
  8. Don’t take herbs or dietary supplements without checking for interactions.
  9.  Beware drug-alcohol interactions.
  10. Inquire about drug-disease interactions. Some medications
    can make certain conditions worse.

You will find far more information in the book. We also welcome your comments in the section below called “ADD MY THOUGHTS.” And please vote on this article at the top of the page.

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  1. Susan

    Not all Doctors are “A” students.

  2. Ilmar
    western australia

    Have not perused your book- but here is something for a book: as there was some time when one could do high living and low thinking, daily excercises of 4.5 km in 50 minutes for number of years notwithstanding couple of coronaries and a stroke with a help of CAPTOPRIL (no coughs-beautiful). Certain Rhodes Scholar(?) fresh medico with a brand new script pad insisted to add Norvasc as combiner, no any instructions…

    Few days later, during my brisk walk, found mayself several times flat on tarmek, that was 14 years ago, resulted in failure to left desending hart section. Pacemaker with 3 electrodes did not restore dead LH desending chamber. My questions to the Medical Fraternity were answered with thundering silence!

    One can not walk, but at age of 92, we are still here… IB

  3. Hans
    Kitchener, ON

    I have learned that your doctor’s behaviour depends very much on where she/he studied medicine.

    My lady generalist, a muslim lady from Algeria studies in France; my Dentist is Indian and my pharmacist is Chinese. They all are very forthcoming with advice, and I feel being well taken care of. I don’t even pay a cent, because I live in Ontario, Canada. So much for our superior health care system, recently maligned by your Vice President Mike Pence!
    Do you think that Trump – Pence an their whole gang doe know what they are doing to you and the rest of the world? I for one doubt it! Except for Rex Tillerson but, unfortunately, he will not last long in his function as secretary of state. So long!

  4. HC

    Since Hibiscus Tea acts like an Ace Inhibitor to lower blood pressure could this tea also be lethal to mix with ARB’s?

  5. Cathy
    Atlanta, Tx

    I need to do more research, I found this after my G.P. put me back on hydralazine while I’m already taking metoprolol and lorsartan and I have stage 4 kidney failure, so seeing the talk about kidneys, potassium levels have me concerned.

  6. Sandy

    I kinda have that baby face too when in actuality I’m 25, hedging on 26 soon. Have been through a lot in my two and a half decades, and at times it’s incredibly sefled-feating. Hard to overcome. But standing firm on the promise that every struggle and stumble has served an ultimate purpose. That redemption will win.Always love reading your stuff! tmz

  7. William
    Richmond, VA

    I take Lisinipril and Amlodipine besolate. When my podiatrist prescribed some Bactrim, I got a fever and a speckled chest. My GP said I must be allergic and to stop the Bactrim. I stopped it and the symptoms went away. I never had a problem with antibiotics before.

  8. Ann

    How much Lisinopril and Lasartan could make a person die? Do you know what the lethal dose is?

  9. Muazzez Eren
    Port Angeles, WA 98362

    Recently, some of your readers have asked about the use of Beet juice to lower blood pressure. You have responded that beet juice has been shown to have that effect. Is that characteristic unique to beet juice only? Would eating beets every day or beet pickles have the same effect? Also, would the use of beets in any form regularly interact with any other medicines? Thanks for any information. Best regards,

    Muazzez Eren

  10. angelo decapua
    delray beach fl.

    If I hear how DR’s are overworked again I will scream. If the money hungry docs didn’t try to fill every 13 minutes with a patient they would have time. And also, most don’t really care anymore, just shove a prescription at you and send you out. If there is a problem with it, come back and pay me another co pay and we will check out the problem. Next?
    I have been telling my family, doctors will kill you, not intentionally but once you get in the mill, watch out.
    My family now uses Peoples Pharmacy as our bible.

    I don’t remember the date, sometime in the a sixties or seventies the doctors went on strike in Canada for three months and for the first time the death rate went down. Go figure. Sometimes we do need them for broken limbs etc. The rest of the time I go to alternative medicine.
    82 and still lifting weights five times a week and healthier that most of my friends who are on more meds that I can count.
    I started taking digestive enzymes with my meals and what a difference. No antacids any more or bloated stomach….And no side effects…

    • Angelo
      Mill Creek WA

      Thanks for the tip on digestive enzymes, Angelo. Will try them. Congrats on working out with the weights at age 82 five times a week. I turned 80 last month and continue a life-long habit of working out with weights. Getting compliments from others. The idea is to open up the capillaries so more blood feeds the heart.

  11. Isabel
    United States

    My spouse has the dry hacking cough from valsartan which the allergy doctor took him off. He was also at the same time taking carvedilol at the same time. The heart doctor refused to take him off of cavedilol but lowered the dosage from 50mg to 25mg. He is still coughing and it is so upsetting to see him suffer for such a long time. When he was on amiodarone his surgeon took him off of amiodarone and the cough lasted two months. That was better than what was anticipated that the cough would last til labor day.
    He was great until the first of this year when he was given Ranexa and his kidney doctor had to take him off of that since it was bothering his kidneys. Then an allergy doctor took him off valsartan because of the cough. We are at our wits end. Is there anyone who can help let us know how to stop this cough?

  12. Darlene

    I am angry. One afternoon after a particularly invigorating massage I was suddenly in pain in my right leg from groin to knee and very weak. that evening I fell twice trying to go up steps. my leg just would not support my attempt. the pain kept me awake most nights for the next week and I was almost completely immobilized. it came into my mind to “check your meds.” remembering that the most recent prescription added was Losartan, I checked it out online and read as possible side effects
    “weakness in the arm or leg on one side of the body, sudden and severe weakness in the arms, hands, legs, or feet
    general tiredness and weakness
    muscle pain or stiffness
    If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional: •body aches or pain, •joint pain, •lack or loss of strength, •pain in the knees or legs , unusual weakness or heaviness of the legs.”

    CLASSIC TEXTBOOK. Informing my doctor, I stopped the Losartan.,, and in about 4 days the pain was gone and gradually over the next two-three weeks the weakness also subsided.
    Of course my doctor could not let me go without some pill for my high blood pressure and so far I have not noticed a side effect but I am sure there will be.

  13. Nanci L.
    Arlington Heights, IL

    Good article except the part about asking your doctor about drug interactions and also checking on the how the drug interacts with food.

    I see a cardiologist, a rheumatologist, have a primary doctor, and none of them ever give me that information!! I asked one cardiologist about the side effects and interactions about a new Beta Blocker he was prescribing. His answer, “I don’t know.”

    I changed doctors, but still have to ask. Current heart doc looks it up in his desk reference. If I don’t ask, he just writes the script with no instructions.

    The pharmacist is better and always asks me if I have any questions.

    It would be nice if doctors were more knowledgeable about the side effects of the meds they pass out like candy.

    I have a friend 85 years old who takes a Beta, an Ace, and a CCB + a diuretic at fairly high doses. His BP is quite low . He said he passed out briefly in his garage at one time. But never questions his meds.
    Doctors are overworked but they should do a better job of informing their patients of potential drug interactions and side-effects.

  14. Bill

    This was a very good article. I take Micardis and was very interested in what this article had to say. TY

    • Marge
      Champaign il

      I was a retired public health nurse who visited many people in there homes, I found that people never questioned that something prescribed by their doctor could be causing them a problem, they had unquestioned confidence in their physician. Also they never question that a drug they had taken for years could be causing a problem now. Both assumptions are wrong!

  15. robert hartwig

    how about a combination of lisonopril and bisoprolol ? is this dangerous ?

    • Leandro Zuniga

      The best med is natural period, no doctor know when is the day, they gonna kill you, all i do is a balanced nutrition consumed daily and herbs

  16. Marlene

    Thanks for the Heads up !!

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