Low potassium is a condition in which the potassium level in your bloodstream is lower than is typical. The medical term for this condition is hypokalemia. Potassium helps carry electrical signals to cells in your body. It is needed for healthy function of nerve and muscles cells, especially those in the heart.
Typically, your blood potassium level is 3.6 to 5.2 millimoles per liter (mmol/L). A blood potassium level of less than 3.0 mmol/L can be life-threatening. It requires urgent medical attention.
Low potassium has many causes. The most common cause is potassium loss in urine due to prescription medicines that increase urination. These types of medicines, also known as water pills or diuretics, typically are prescribed to treat high blood pressure or heart disease. But these medicines may be prescribed to treat swelling of any type.
Vomiting, diarrhea or both also can result in potassium loss. Sometimes, low potassium is caused by not getting enough potassium in your diet.
Low potassium typically is detected when you have a blood test due to an illness or the use of diuretics. It is rare for low potassium to cause symptoms if you are feeling well.
Low potassium symptoms include:
- Weakness.
- Fatigue.
- Muscle cramps.
- Constipation.
- Irregular heart rhythms, called arrhythmias.
Irregular heart rhythms are the most worrisome complication of very low potassium levels, particularly in people who have heart disease.
Talk to your healthcare professional about what your blood test results mean. You may need to change a medicine that's affecting your potassium level. Or you may need to treat another medical condition that's causing your low potassium.
Treatment for low potassium depends on the underlying cause. It may include potassium supplements. Don't start taking potassium supplements without talking to your healthcare professional.
Show References
- Elsevier Point of Care. Clinical Overview: Hypokalemia. https://www.clinicalkey.com. Accessed Feb. 28, 2025.
- Hypokalemia. Merck Manual Professional Version. https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/electrolyte-disorders/hypokalemia?query=Hypokalemia. Accessed Feb. 28, 2025.
- Mount DB, et al. Causes of hypokalemia in adults. https://www.uptodate.com/contents/search. Accessed Feb. 28, 2025.
- Mount DB, et al. Clinical manifestations and treatment of hypokalemia in adults. https://www.uptodate.com/contents/search. Accessed Feb. 28, 2025.
Original article: https://www.mayoclinic.org/symptoms/low-potassium/basics/definition/SYM-20050632