Quick answer

Ask your pharmacist or doctor before combining. ACE inhibitors such as lisinopril and ARBs such as losartan reduce the potassium lost in urine, and their labels flag potassium supplements and potassium salt substitutes, which can hold 440 to 2,800 mg per teaspoon. Other blood pressure medicines affect potassium differently.^1,2,3,4

Key facts

The lisinopril label lists potassium supplements and potassium-containing salt substitutes among the risk factors for hyperkalemia, along with kidney problems and diabetes.³
The losartan label says not to use potassium supplements or potassium salt substitutes without consulting a healthcare provider.⁴
In lisinopril's clinical trials, hyperkalemia occurred in 2.2% of people treated for high blood pressure.³
MedlinePlus lists potassium supplements among nonprescription products that may interact with lisinopril and with losartan.^5,6

Ask your pharmacist or doctor first

ACE inhibitors such as lisinopril and angiotensin receptor blockers (ARBs) such as losartan reduce the potassium lost in urine and can make blood potassium too high (hyperkalemia), especially in people with kidney problems. Their labels list potassium supplements and potassium-containing salt substitutes among the risks, and the labels and MedlinePlus tell people to check with their doctor before using them.^1,2,3,4,5,6

On the medicine's label

What is documented

NIH explains the mechanism. ACE inhibitors and ARBs decrease the amount of potassium lost in urine, which can make blood potassium too high, especially in people with kidney problems. Experts recommend monitoring potassium in people who take them.^1,2

This one is printed on the medicines' labels. The lisinopril label tells prescribers to check potassium periodically and tells patients not to use potassium salt substitutes without consulting their physician. The losartan label says the same about potassium supplements and salt substitutes.^3,4

Which blood pressure medicines this covers

The warning is about ACE inhibitors, such as benazepril and lisinopril, and angiotensin receptor blockers (ARBs), such as losartan. NIH notes these are also used for heart failure and to slow kidney disease.^1,2

Spironolactone, used for blood pressure and fluid buildup, also keeps potassium in the body. Its label goes further and tells patients to avoid potassium supplements.^7,8

Avoid the combination unless your doctor advises it

The spironolactone label says potassium supplements taken with it may lead to severe hyperkalemia, and that patients should be advised to avoid potassium supplements and foods high in potassium, including salt substitutes.^7,8

On the medicine's label

Thiazide and loop diuretics work the other way: they increase the potassium lost in urine and can make it too low. Some people who take them are prescribed potassium, which is a decision for the prescriber.^1,9

The sources on this page do not address other kinds of blood pressure medicine. That is not a finding either way, so ask your pharmacist about yours.

Salt substitutes count too

Many salt substitutes swap some or all of the sodium chloride for potassium chloride, at about 440 to 2,800 mg of potassium per teaspoon. MedlinePlus tells people on lisinopril or losartan to talk to their doctor before using them.^2,5,6

What to ask your pharmacist

Is my blood pressure medicine an ACE inhibitor, an ARB or a potassium-sparing diuretic?
Is my potassium being checked, and how often?
Do any of my supplements, electrolyte drinks or salt substitutes contain potassium?
Do I need to limit potassium-rich foods, or only supplements and salt substitutes?

Carry the labels of your supplements and drink mixes when you see your pharmacist. Multivitamins that include potassium typically carry about 80 mg, and the total from every product is what counts.²

Questions people ask

Can I eat bananas if I take lisinopril?

Ask your doctor. NIH notes that in people taking ACE inhibitors, high blood potassium can occur even with typical amounts of potassium from food, especially with kidney problems, so whether to limit foods such as bananas is an individual decision.^1,2

Does a small 99 mg supplement matter?

The labels make no exception for small amounts, and potassium adds up across supplements, drink mixes, salt substitutes and food. Ask your pharmacist to count it with you.^3,4

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.