Potassium Interaction with Blood Pressure Pills: A Deadly Mix

Do you know how your diet relates to your medication? Prescribers don’t always mention dietary precautions when they hand out a prescription. But often they should discuss this to avoid a potential problem. We get especially excited about a potassium interaction with an ACE inhibitor.

Beware a Potassium Interaction with Losartan:

Q. I’d heard that potassium is important for blood pressure. Being a good patient, I started using a potassium chloride salt substitute after I was diagnosed with hypertension.

Within several weeks, I noticed that I wasn’t feeling right. My pulse was in the 40s, and my blood pressure was low.

Then I read the pharmacy sheet on the losartan that I was taking. It warned against taking potassium. Once I stopped the salt substitute, everything returned to normal.

A. You dodged a bullet. Blood pressure pills like losartan and lisinopril preserve potassium. Tens of millions of people take such ARBs or ACE inhibitors every day. They must be especially careful about supplemental potassium as you might find in a salt substitute.

When levels of this crucial mineral get too high (above 5.5 mmol/L), it can lead to slow heart rate, palpitations, weakness, tingling in hands, feet or lips and confusion. Most dangerous is a fatal heart rhythm disruption.

To determine whether someone is taking an ACE inhibitor, check to see if the name ends in “pril.” An angiotensin receptor blocker (ARB) like losartan usually has a name ending in “sartan.”

Enalapril and a Potassium Interaction:

Q. My pharmacist said I could have killed myself if I kept taking potassium with my blood pressure medicine. My new doctor switched me to enalapril and didn’t mention any precautions.

Before this I was on hydrochlorothiazide and potassium supplements. It’s lucky my pharmacist noticed I had changed blood pressure prescriptions when I went to have the potassium refilled.

I have also used Lite Salt or NoSalt for years to reduce my sodium intake. Do I need to stop using the salt substitute as well?

A. Potassium-based salt substitutes like the ones you have been using can be a good way of cutting back on sodium and getting extra potassium. But in combination with medicines such as Vasotec (enalapril), Capoten (captopril), Lotensin (benazepril), Aceon (perindopril), Accupril (quinapril), Altace (ramipril), Mavic (trandolapril), or Zestril (lisinopril), salt substitutes and potassium supplements could be disastrous. Too much potassium can cause fatal heart rhythms.

Overlooking the Potassium Interaction Was a Medical Mistake:

This was an example of a serious medical mistake. The new physician clearly did not take time to review all the prior medications that had been prescribed and notice the potassium interaction. People take potassium supplements to compensate for the depletion of potassium brought on by diuretics like hydrochlorothiazide (HCTZ) or furosemide (Lasix). But when the prescription was changed to the ACE inhibitor enalapril, the doctor should have been far more careful to check the medical records and ask about salt substitutes. Fortunately, the pharmacist saved the day (and potentially your life).

Such mistakes are far more common than most people realize. That’s why we wrote Top Screwups Doctors Make and How to Avoid Them. It offers hundreds of questions to ask and tips to prevent this kind of potentially lethal error. In particular, there is information on common mistakes made with ACE inhibitors, diabetes drugs, hypothyroidism and heartburn. Here’s a link to the People’s Pharmacy Store if you would like a copy.

Other Medications That Upset Potassium Balance:

In people whose kidneys don’t work efficiently, an ACE inhibitor drug all by itself could lead to high potassium (Turgutalp, Renal Failure, Oct. 2016). So can NSAID pain relievers such as diclofenac, ibuprofen, meloxicam or naproxen. When doctors prescribe spironolactone or an ARB blood pressure pill such as losartan, they should monitor potassium to make sure it doesn’t get too high.

Learn More:

Potassium isn’t the only potential problem. Vitamin and mineral interactions with some medicines can be life threatening. We are sending you our Guide to Drug and Nutrient Interactions. It tells which prescription drugs can provoke nutritional deficits and alerts you to problems that may occur if you take supplements with your medications.

You can learn more about blood pressure medication, other ways to control hypertension and the hazards of interactions in our eGuide to Blood Pressure Solutions.