Not Getting Enough Potassium? It Could Affect Your Blood Pressure

Potassium is an important mineral that you get from the food you eat. It’s often referred to as an electrolyte along with sodium, calcium, and magnesium. 

All of these electrolytes keep your organs working normally. But the heart and blood vessels are especially sensitive to potassium. When your potassium levels are low, your blood pressure may rise. Here’s how potassium can affect your blood pressure, what foods are high in potassium, and when supplements might be helpful.

Does potassium lower blood pressure?

Blood pressure is affected by many different things. Potassium is one important factor. It helps the blood vessels to relax. If your potassium level is low, then your blood vessels can tighten, or constrict. This can cause your blood pressure to run higher. 

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Many people think sodium is the main electrolyte that affects blood pressure. But sodium and potassium both play an important role. Sodium (found in salt) tends to raise blood pressure, while potassium brings it down. They also work as a team. If your diet includes a good amount of potassium, it can help your kidneys eliminate excess sodium. Likewise, cutting back on salt can also help your potassium levels.

For most people, the impact of potassium on blood pressure is small. But it is still important. 

What are the benefits of getting more potassium?

When you eat foods that are high in potassium, they can can help: 

• Reduce the effect of salt on blood pressure

• Relax the blood vessels

• Provide fiber, vitamins, antioxidants, and other important nutrients

• Protect your heart and brain health

Most people can easily get potassium from their diet. Common potassium-rich foods include:

• Avocados

• Baked potatoes and sweet potatoes

• Raisins and dates

• Bananas

• Spinach and most other greens

• Beans and lentils

• Yogurt and milk

• Mushrooms

• Salmon, tuna, and other fish

• Oranges and other citrus fruits

• Tomatoes

How do you know if you need more potassium?

You may not have any symptoms if your potassium level is a little low. But common symptoms of low potassium include:

• Muscle aches

• Heart palpitations

• Tingling or numbness

• Fatigue

• Constipation

The only way to be certain of your potassium level is to get your blood tested. Your provider can order this with your routine blood work. 

When should you take a potassium supplement for blood pressure?

Most people get enough potassium from their diet. But if you have a low blood level of potassium, you may need a supplement. Some things that might cause you to need a supplement include:

• Certain medications — like diuretics (water pills), laxatives, and insulin 

• Diarrhea or vomiting

• Excessive sweating

• Eating disorders or restrictive diets

In general, it’s best to get a prescription for a supplement from your provider. This is for several reasons:

• They can recommend the right dose based on what your body needs.

• Prescription supplements can provide a much higher dose than over-the-counter supplements — if that’s what you need.

• Your potassium blood level should be monitored when you take potassium supplements. Especially since high potassium levels can be very dangerous.

If you are already following a low salt diet, a potassium supplement will probably not make your blood pressure lower. Potassium supplements are not usually a substitute for blood pressure medication. It’s also important to note that if you start a potassium supplement, it may take several weeks for it to affect your blood pressure.

What are the risks of taking potassium supplements?

The kidneys are responsible for keeping your potassium levels normal. So if you have kidney disease, potassium supplements can be dangerous. Some medications can also affect the way the kidneys handle potassium. That’s one more reason why it’s important to talk to your provider and get your blood tested before starting a supplement. 

If your potassium levels get too high, it can cause serious heart rhythm problems. In the worst cases, this can be fatal.

Common side effects of potassium supplements include:

• Nausea and vomiting

• Abdominal pain

• Diarrhea

• Throat irritation 

Is it OK to take potassium supplements with blood pressure medications?

Potassium can interact with a variety of other blood pressure and heart medications. These include:

• Diuretics (water pills): Some of these can lower potassium levels. Other diuretics will raise your potassium. 

• ACE-inhibitors and ARBs: If you take one of these drugs, adding a potassium supplement could make your potassium level very high. 

That doesn’t mean you can’t take potassium with these drugs. It will depend on what other meds you take and what other conditions you have. Your provider will be able to work with you to keep your potassium level in balance.

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Written by:

Sarah A. Samaan, MD

Sarah Samaan, MD, FACC, FACP, FASE is a board-certified cardiologist who practiced clinical cardiology for nearly 30 years. She is a member of the American College of Cardiology, the American College of Physicians, and the American Society of Echocardiography.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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