When to see a doctor

By Mayo Clinic Staff

In most cases, low potassium is found by a blood test that is done because of an illness, or because you are taking diuretics. It is rare for low potassium to cause isolated symptoms such as muscle cramps if you are feeling well in other respects.

Low potassium symptoms may include:

  • Weakness
  • Fatigue
  • Muscle cramps
  • Constipation

Abnormal heart rhythms (arrhythmias) are the most worrisome complication of very low potassium levels, particularly in people with underlying heart disease.

Talk to your doctor about what your blood test results mean. You may need to change a medication that's affecting your potassium level, or you may need to treat another medical condition that's causing your low potassium level.

Treatment of low potassium is directed at the underlying cause and may include potassium supplements. Don't start taking potassium supplements without talking to your doctor first.

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June 23, 2022