What should you know about onset of rhabdomyolysis?

Rhabdomyolysis happens when damaged muscle fibres release their contents into the bloodstream. It may follow unusually intense exercise, a crush injury, prolonged pressure on a muscle, severe heat exposure, seizures, or certain medicines and illnesses. Muscle soreness after exercise is common, but rhabdomyolysis can cause pain or swelling that feels more severe than expected, weakness, unusual tiredness, and urine that looks tea-coloured or dark. Symptoms can appear after the triggering event rather than immediately. You cannot confirm the condition by appearance alone; a clinician uses an examination and blood and urine tests to assess muscle injury and kidney function.

Stop strenuous activity and arrange same-day medical advice if symptoms are unusually intense or include weakness or dark urine. Do not attempt to exercise through the pain. Avoid taking extra over-the-counter pain medicine or supplements without checking with a clinician, because some products may affect the kidneys or interact with medicines. Tell the clinician about recent exercise, heat exposure, injury, new medicines, alcohol or drug use, and any change in urine. Small, regular sips of fluid may be reasonable if you can drink normally, but do not delay assessment to manage this at home. For ordinary post-exercise discomfort, see [Muscle Soreness After Exercise](/symptoms/muscle-soreness-after-exercise/).

Seek urgent medical care now for dark or very reduced urine, severe muscle swelling, rapidly worsening pain, pronounced weakness, confusion, fainting, trouble breathing, or inability to keep fluids down. These signs can accompany significant muscle injury or kidney and electrolyte problems. Emergency assessment is also appropriate after a major crush injury, prolonged immobility, or severe heat illness, even if muscle pain has not fully developed. Bring a list of medicines and describe when the symptoms began.

Could my symptoms be rhabdomyolysis, and which blood or urine tests are needed? What activity, medicines, and fluids should I avoid while recovering? When should kidney function be checked again, and how should I return to exercise safely?