Potassium supplements: what they do and who needs them

Potassium keeps your muscles, heart, and nerves working. Low potassium (hypokalemia) can cause weakness, cramps, and irregular heartbeat. If your doctor says your levels are low or a medicine is draining potassium, a supplement can help restore balance. This page explains the common forms, how to take them safely, and what to watch for.

Who needs potassium supplements?

People who lose potassium from the body are the most common candidates: those on loop or thiazide diuretics, people with prolonged vomiting or diarrhea, and some with specific medical conditions like certain kidney problems. Athletes who sweat a lot and people who follow very restrictive diets may also need extra potassium. Your doctor should confirm with a blood test before you start taking pills — don’t guess.

Doctors may prescribe supplements when diet alone won’t fix levels. Foods rich in potassium include bananas, potatoes, beans, spinach, and avocados. If you can add those to your meals, that’s often safer than jumping straight to pills.

Common forms and how to take them

Potassium supplements come in several forms: potassium chloride, potassium citrate, and others. Over-the-counter options are usually low-dose tablets (often labeled around 99 mg elemental potassium). Prescription doses are higher and come as extended-release tablets or liquid. Extended-release pills are made to be swallowed whole — don’t crush or chew them.

Take potassium with food to reduce stomach upset. Splitting the total daily dose into two or three smaller doses often helps with tolerance. Always follow the dose your provider gives you and the directions on the bottle.

Watch for interactions. Potassium levels can rise dangerously high (hyperkalemia) if you take supplements with ACE inhibitors, ARBs, potassium-sparing diuretics (like spironolactone), or certain antibiotics such as trimethoprim. NSAIDs and some blood pressure medicines can raise potassium too. Tell your prescriber about all medicines, supplements, and salt substitutes you use.

Know the warning signs: new or worsening muscle weakness, numbness, a slow or irregular heartbeat, or feeling faint. If any of these happen, seek medical care. Routine blood tests are the only reliable way to track potassium safely when you’re on supplements.

Thinking of buying online? Use licensed pharmacies, check that the site lists a contact and pharmacist, and read labels carefully. Avoid any seller that won’t provide ingredient details, lot numbers, or expiry dates. Cheap isn’t worth risking your heart rhythm.

If you’re unsure whether you need a supplement, ask for a blood test. Small lifestyle changes — eating a few extra potassium-rich foods — can be enough for many people. When supplements are needed, use them under supervision and keep track of tests and medicine interactions.