What should you know about hypokalemia and rhabdomyolysis?

Potassium helps muscle and nerve cells work normally. Low levels may cause cramps, weakness, constipation, or changes in heart rhythm. Rhabdomyolysis occurs when damaged muscle releases substances into the bloodstream, often after intense exertion, a crush injury, prolonged immobility, heat illness, seizures, infection, or a medicine-related effect. Low potassium can be one contributor, but it is not the only possible cause. Muscle soreness after exercise can be ordinary recovery, yet unusually severe pain, weakness, swelling, or dark urine requires more attention.

Stop strenuous exercise and seek medical advice if severe soreness or weakness is developing. Clinicians may check potassium and other electrolytes, kidney function, muscle enzymes, urine, medicines, and the reason potassium became low. Do not self-treat with potassium tablets or large amounts of electrolyte drinks; the right replacement depends on the level, symptoms, kidney function, and heart rhythm. Keep a record of vomiting, diarrhoea, sweating, new medicines, supplements, and recent exertion. Read about [Muscle Soreness After Exercise](/symptoms/muscle-soreness-after-exercise/).

Get urgent medical help for severe or worsening muscle weakness, inability to move normally, marked muscle swelling, dark or tea-coloured urine, very little urine, fainting, chest discomfort, or a fast or irregular heartbeat. These features can signal significant muscle injury, electrolyte disturbance, or kidney stress and should not be monitored at home.

Ask what caused the potassium change, whether your heart rhythm and kidney function need monitoring, and which medicines or supplements should be paused. Ask when gentle activity can resume and which symptoms should prompt immediate reassessment.