The Link Between Low Potassium and Swollen Feet

If you've ever looked down at your feet after a long day only to find them puffier than usual, you're not alone. Swollen feet and ankles also known as edema can happen for a variety of reasons, ranging from hot weather to dietary choices. But one often-overlooked cause might surprise you: low potassium.

What’s the link between potassium and swelling?

According to Briana Costello, MD, a cardiologist at The Texas Heart Institute, potassium plays a key role in regulating fluid balance in the body though not always directly. “Potassium is very much related to swelling in the legs, not directly but indirectly. People who are on diuretics or other medications often lose potassium,” she explains. This electrolyte is vital for muscle function (especially in the heart), and when levels dip too low, it can throw off your body’s fluid balance.

How does potassium impact swelling in the feet?

Potassium helps regulate sodium levels and maintain a proper balance of fluids. When potassium levels are too low (a condition known as hypokalemia), it may exacerbate fluid retention, especially for people already prone to swelling due to medication use or underlying health issues. In fact, the condition can also contribute to heart rhythm abnormalities making it a critical mineral to monitor, particularly if you have cardiovascular concerns.

Common symptoms of low potassium include:

• Muscle weakness or spasms

• Fatigue

• Tingling or numbness

• Constipation

• Heart palpitations

• In severe cases: low blood pressure, fainting, or excessive thirst and urination

Other reasons your feet might be swelling

While low potassium could be a factor, there are many other causes of swollen feet and legs, including:

• Long periods of standing or sitting

• High salt intake

• Tight clothing or restrictive footwear

• Heat and humidity

• Certain medications (such as antidepressants, steroids, or high-estrogen birth control pills)

• Medical conditions like blood clots, leg infections, or heart, kidney, or liver disease

• Pregnancy or menstruation

• Carrying excess weight

How to reduce swelling in the feet

Managing swelling starts with identifying the root cause. A health professional can help assess whether your symptoms stem from low potassium, medications, or lifestyle habits. Still, there are general tips that may help relieve mild swelling:

• Elevate your feet when resting to reduce fluid buildup.

• Limit sodium intake to prevent excess water retention. “I always advocate for a low-sodium or low-salt diet,” Dr. Costello says. “It can help reduce high blood pressure and improve cardiovascular health overall.”

• Incorporate movement throughout the day to support circulation ankle circles, calf raises, or short walks can all help.

• Wear compression socks if you’re on your feet for long stretches or flying.

• Hydrate properly dehydration can actually lead to water retention.

Foods to support healthy potassium levels

Bananas may get the most press, but they’re far from the only potassium-rich food out there and some options may be better overall. “I would argue having spinach, broccoli, and potatoes is probably better than eating a lot of bananas because of the sugar content,” Dr. Costello adds. Other great sources include:

• Leafy greens (like kale and Swiss chard)

• Sweet potatoes and regular potatoes

• Avocados

• Beans and lentils

• Yogurt and milk

• Nuts and seeds

The Harvard T.H. Chan School of Public Health recommends getting potassium from whole food sources as part of a balanced diet, which can also support overall cardiovascular health.

When to see a doctor

If your foot or leg swelling comes on suddenly, is accompanied by pain, or doesn’t go down with rest and elevation, check in with your doctor right away. It may be a sign of a more serious issue, like a blood clot or organ dysfunction. Similarly, if you suspect low potassium or start noticing unusual symptoms like muscle cramping, palpitations, or dizziness, a simple blood test can determine your electrolyte levels and help guide treatment.

Final thoughts

Swollen feet may seem like a minor annoyance, but they can offer important clues about your body’s internal balance. While low potassium isn’t the only reason for edema, it’s worth paying attention to especially if you’re on medications or managing a heart condition. A nutrient-rich diet, plenty of movement, and guidance from your doctor can go a long way in keeping your legs (and heart) healthy.

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