Rhabdomyolysis: Symptoms, Causes, CK Levels and Treatment

Rhabdomyolysis, often shortened to rhabdo, is a condition in which damaged skeletal muscle breaks down and spills its contents into the blood. These contents include myoglobin (the protein that gives muscle its red color), potassium, phosphate and the enzyme creatine kinase (CK). In large amounts they can injure the kidneys and upset the heart rhythm. About 26,000 people in the United States develop rhabdomyolysis each year, according to Cleveland Clinic.

The classic rhabdomyolysis symptoms are muscle pain, weakness and dark urine the color of tea or cola. The diagnosis is made with a blood test: a CK level at least five times the upper limit of normal. Treatment is mainly intravenous (IV) fluids given early, plus treating the cause. Most people recover fully, but severe cases can lead to kidney failure.

Key takeaways

• Rhabdomyolysis is muscle breakdown that releases myoglobin, potassium and CK into the blood; the main danger is kidney injury and dangerous potassium levels.
• Warning signs: muscle pain far worse than expected, weakness, and tea- or cola-colored urine, usually 1 to 3 days after the muscle injury. Many people do not have all three.
• Diagnosis relies on a CK blood test above five times the upper limit of normal, repeated to see whether it is rising or falling.
• Early IV fluids are the cornerstone of treatment; adding bicarbonate has not shown a clear benefit.
• Exercise-induced rhabdo usually has a good outlook; rhabdo after trauma, sepsis or cardiac arrest is more dangerous.

What is rhabdomyolysis?

What is rhabdo in rhabdomyolysis? "Rhabdo" is simply the everyday short name for rhabdomyolysis. The full term describes the destruction of skeletal muscle with leakage of its contents into the bloodstream.

It was first described in 1941 in people trapped under rubble during bombings, whose kidneys contained a brown pigment: myoglobin. When muscle is damaged, myoglobin is released and filtered by the kidneys, where it breaks down into substances that harm kidney cells. Released potassium and phosphate add to the risk.

Rhabdomyolysis ranges from a silent rise in CK after a hard workout to a life-threatening illness with kidney failure, depending mostly on the cause.

Rhabdomyolysis causes and risk factors

The main rhabdomyolysis causes are:

• Trauma and compression: crush injuries, severe burns, electrocution, lengthy surgery, or lying on the floor for hours after a fall (a "long lie").
• Exertion and heat: intense or unaccustomed exercise, a marathon or military training, heat stroke. Fit people are not protected.
• Medicines and substances (see the next section).
• Infections: influenza and other viral infections, and sepsis. In children, infections are the leading cause.
• Seizures, and low blood potassium or phosphate.
• Inherited muscle and metabolic diseases, such as McArdle disease, Duchenne muscular dystrophy and mitochondrial disorders.
• Reduced blood supply to a limb, and myositis (muscle inflammation).

Higher-risk groups include endurance athletes, military recruits, firefighters, outdoor and farm workers, and adults over 65. In a study of 47,944 Black US Army soldiers, sickle cell trait raised the risk of exertional rhabdomyolysis by about 54%; recent statin use (2.9 times) and antipsychotics (3 times) mattered more. It did not increase the risk of death. See also our article on sickle cell disease in young adults.

Can dehydration cause rhabdomyolysis?

Not on its own, according to the CDC's occupational health institute (NIOSH): dehydration does not cause rhabdo, but it makes it worse because the body can no longer flush out the released proteins and electrolytes. MedlinePlus lists severe dehydration among the conditions linked to rhabdo, usually together with heat or hard exercise. Our guide to dehydration and blood pressure explains how fluid loss affects circulation.

Drugs that can cause rhabdomyolysis

What are the most common drugs causing rhabdomyolysis? Cholesterol-lowering drugs head most lists, but serious cases are rare. In a US study of 252,460 people taking lipid-lowering drugs, hospitalized rhabdomyolysis occurred 0.44 times per 10,000 person-years with atorvastatin, pravastatin or simvastatin alone. That is one case per 22,727 people treated for a year. Risk rose with a fibrate (2.82 per 10,000) and with a statin-fibrate combination, especially in older adults with diabetes.

Other links include:

• Antipsychotics, some antidepressants and some antivirals.
• Gabapentinoids (gabapentin, pregabalin), often in older people also taking statins.
• Drug interactions with statins, such as the breast cancer drugs called CDK4/6 inhibitors.
• Alcohol, cocaine and other stimulants; amphotericin B.

Never stop a prescribed drug on your own. If you develop unexplained muscle pain or weakness on a statin, your doctor can check a CK test; our article on statin muscle pain and the CK test explains what the result shows.

Rhabdomyolysis symptoms and early signs

The classic triad is muscle pain, weakness and dark urine. Symptoms usually start 1 to 3 days after the muscle injury, and many people do not have all three. NIOSH lists these early signs:

• Muscle cramps, aches or pain more severe than you would expect after the activity.
• Tea- or cola-colored urine.
• Weakness or fatigue, for example being unable to finish a workout you normally complete.

Other possible signs are swollen, tender or stiff muscles, passing less urine, nausea, fever and, in severe cases, an irregular heartbeat or loss of consciousness. Older adults may show only limb swelling and weakness, and in one pediatric series only 5.4% of children reported dark urine.

Rhabdomyolysis urine color

Myoglobin turns urine reddish brown, from tea-colored to cola-colored. Our urine color chart explains other causes of dark urine.

How rhabdomyolysis is diagnosed

What are the diagnostic criteria for rhabdomyolysis? There is no single worldwide definition. Most studies define it as a CK level more than five times the upper limit of normal, together with a fitting history (exertion, trauma, a drug, an infection) and symptoms. Severe rhabdo is often defined as CK above 5,000 U/L. Symptoms alone cannot confirm rhabdo, because heat exhaustion and heat cramps can feel the same.

The usual workup includes:

• A CK (CPK) blood test, repeated to see whether the level is rising or falling.
• Kidney tests: creatinine, urea and urine output, often as a kidney function panel.
• Electrolytes: potassium, calcium, phosphorus and bicarbonate.
• A urinalysis and sometimes a myoglobin test in blood or urine.

Rhabdomyolysis CK levels over time

CK rises during the first 12 hours after the muscle injury, peaks within 3 to 5 days, and returns to baseline over the following 6 to 10 days. Myoglobin is also measured; in one cohort of 484 patients, blood myoglobin above 15 mg/L was strongly associated with kidney injury, but data on myoglobin as an early marker remain limited. A CK that keeps rising despite treatment suggests ongoing muscle damage, such as compartment syndrome.

The urine dipstick clue

A urine dipstick reacts to the heme part of both hemoglobin and myoglobin. When the strip is positive for "blood" but the microscope finds few or no red blood cells, myoglobin in the urine is likely. This pattern is different from true blood in the urine (hematuria). The urine is also often acidic and may contain protein or casts.

Reference values: CK, potassium, creatinine and other labs

Ranges vary between laboratories: compare with the range on your own report. Usual adult values (MedlinePlus):

In a 2024 meta-analysis of traumatic rhabdomyolysis, low calcium was found in 57% of patients, high phosphate in 33%, high potassium in 31% and low sodium in 23%.

How to read your results

A high CK on its own is not always rhabdomyolysis. Heavy exercise, intramuscular injections, recent surgery, seizures, an underactive thyroid (hypothyroidism) and some medicines all raise CK. The size of the rise, the trend and the kidneys matter most.

CK alone predicts kidney injury poorly. A 2013 Boston risk score combines age, sex, cause and admission creatinine, CK, phosphate, calcium and bicarbonate: 2.3% of the lowest-score patients died or needed dialysis, versus 61.2% of the highest. Related enzymes such as LDH and AST often rise too, because they are also found in muscle.

Rhabdomyolysis treatment

Rhabdomyolysis treatment aims to protect the kidneys and remove the cause.

• IV fluids: fluid replacement is the cornerstone. In crush injuries, reviews advise starting within 6 hours. Too much fluid can also cause harm, so volumes are tailored.
• Treating the cause: stopping a drug, cooling heat stroke, treating infection.
• Correcting electrolytes: high potassium is the one abnormality that needs rapid correction, to protect the heart. Low calcium is usually not corrected early, because giving calcium may worsen muscle injury.
• Dialysis: used for severe kidney damage, on the usual kidney-failure criteria. Some people need it for weeks.
• Surgery: compartment syndrome, a painful buildup of pressure inside a muscle compartment, needs immediate surgical treatment to prevent permanent disability.

Bicarbonate and mannitol were long added to fluids. No randomized trial has compared fluids alone with fluids plus bicarbonate or mannitol, and a 2025 meta-analysis found no protection against kidney injury or dialysis from urine alkalinization.

Some people with mild exertional rhabdo and normal kidney tests can be followed as outpatients; US military guidelines set criteria for outpatient versus hospital care and for discharge. Most others need a hospital stay of a few days.

Recovery, prognosis and complications

Is rhabdomyolysis curable? Yes, in most cases. Prompt treatment lowers the risk of permanent kidney damage. People with milder cases often return to normal activities within a few weeks to a month; some stay tired and sore for a while.

The prognosis depends mostly on the cause. In the Boston study of patients with CK above 5,000 U/L, 8.0% needed dialysis and 14.1% died in hospital, many of them very ill. The combined risk of dialysis or death was 58.5% after cardiac arrest, 41.2% with compartment syndrome and 39.3% with sepsis, compared with 3.2% after exercise and 1.7% with myositis. Up to half of people with rhabdo develop acute kidney injury.

Possible complications include:

• Acute kidney injury and acute tubular necrosis.
• Dangerous heart rhythms from high potassium, and metabolic acidosis.
• Compartment syndrome.
• Disseminated intravascular coagulation (DIC), a clotting disorder.
• Shock and, rarely, death.

Returning to exercise after exertional rhabdo should be gradual and cleared by your doctor; military guidelines describe a step-by-step return to duty and further workup for people at risk of recurrence.

Prevention: training, heat and medicines

Not every cause can be prevented, but many exertional and drug-related cases can:

• Build fitness gradually, over weeks or months.
• Allow 10 to 14 days to adjust to a hot climate, take frequent breaks and use cooling when working in heat.
• Drink fluids during and after strenuous exercise; prefer caffeine-free, low-sugar drinks and avoid alcohol in the heat.
• Do not train hard when you are sick: illnesses such as the flu, and some cold medicines, may increase risk.
• Review your medicines with your doctor or pharmacist, especially statins combined with fibrates or other interacting drugs.
• Stop and seek care if muscle pain is out of proportion or urine turns dark.

Rhabdomyolysis in children, older adults and athletes

Children: a 2025 meta-analysis of 15 studies and 10,514 children found that infections caused 40.6% of cases, trauma 19% and exercise 14.7%. Kidney injury occurred in 21.3% but chronic kidney disease in only 1.1%. Viral infections such as influenza are typical triggers.

Older adults: a long lie after a fall is a classic cause, and symptoms may be atypical, such as swelling and weakness without pain.

Athletes and recruits: in 2025, the US Armed Forces recorded 521 cases of exertional rhabdomyolysis, 39.7 per 100,000 person-years,, highest in recruits and men under 20. In a 2026 review of 65 published cases in athletes (median peak CK 55,000 U/L), 75% had kidney injury and 22% needed dialysis, yet none died and 95% fully recovered their kidney function.

When to see a doctor

Call 911 or go to the emergency room right away if you have:

• Dark, tea- or cola-colored urine, or very little urine, after exercise, heat exposure, an injury or a new medicine.
• A tight, very painful, swollen arm or leg (possible compartment syndrome).
• Weakness, confusion, a racing or irregular heartbeat, or fainting.
• Signs of heat stroke: high body temperature, confusion, collapse.
• An older relative found on the floor after a fall who may have been there for hours.

Call your doctor if muscle pain, weakness or swelling persists for several days after exercise, or if unexplained muscle pain starts on a statin. With symptoms, stop the activity, drink water and get checked: only a blood test confirms rhabdo.

Latest scientific advances in rhabdomyolysis

Urine alkalinization: no proven benefit

A 2025 systematic review and meta-analysis of five studies found that adding sodium bicarbonate to fluid therapy did not significantly prevent acute kidney injury, acute kidney failure or the need for dialysis in rhabdomyolysis. The key treatment remains enough IV fluid, given early.

How much IV fluid? Large data, still no exact answer

A 2025 Japanese study of 5,392 hospitalized patients compared those who received at least 3,500 mL of IV fluid per day in the first 3 days with those who received less. Death or dialysis at discharge did not differ (3.4% vs 3.9%), but fewer patients in the higher-fluid group were still on dialysis when they left hospital (0.4% vs 1.3%). The optimal volume remains unknown.

CK alone is only a fair predictor of kidney injury

A 2026 meta-analysis of 17 studies of traumatic rhabdomyolysis confirmed that people who develop kidney injury have much higher CK levels, but CK alone correctly sorted patients only about 68% of the time. The authors advise using it within a broader assessment. A UK study (NCT07158554) has built a risk score, called REED, for adults 60 and older who develop rhabdo after a long lie on the floor.

Filtering myoglobin out of the blood

Hemoadsorption uses a special filter cartridge to remove myoglobin from the blood. A 2024 European expert consensus suggested considering it when myoglobin exceeds 10,000 ng/mL, ideally within 24 hours. A 2026 meta-analysis found it lowered myoglobin by a median of about 31%, but the certainty of evidence was low, its effect on CK was unclear and no improvement in kidney outcomes has been proven yet.

New trials and surveillance

A US trial at Children's National (NCT06429982) is testing whether adding the steroid dexamethasone to standard care improves pain, hospital stay and kidney complications in non-traumatic rhabdo of unknown or genetic cause, in patients from 6 months of age. Meanwhile, military surveillance shows exertional rhabdo remains common in recruits, with 46.3% of 2025 cases treated in hospital.

Which tests can help?

These tests show how much muscle is damaged and how your kidneys are coping:

• CK (CPK), repeated until it returns to normal, and myoglobin.
• Creatinine, urea (BUN) and eGFR: kidney function.
• Electrolytes: potassium, calcium, phosphorus, sodium and bicarbonate.
• Urinalysis: blood on the dipstick without red cells.
• AST, ALT and LDH: often raised by muscle damage, not only by liver disease.
• For the cause: drug screen, thyroid and infection tests, and genetic tests after repeated episodes.

Reading these results together, with their trend over several days, gives a much clearer picture than a single CK number.

Glossary

• Rhabdomyolysis (rhabdo): breakdown of skeletal muscle with release of its contents into the blood.
• Creatine kinase (CK or CPK): an enzyme found in muscle; a high blood level signals muscle damage.
• Myoglobin: an oxygen-carrying muscle protein that turns urine dark and can injure the kidneys.
• Acute kidney injury (AKI): a sudden drop in kidney function over hours or days.
• Hyperkalemia: high blood potassium, which can disturb the heart rhythm.
• Compartment syndrome: dangerous pressure buildup inside a closed muscle compartment, needing urgent surgery.
• Urine alkalinization: giving bicarbonate to make urine less acidic, an older treatment without proven benefit.
• Hemoadsorption: a blood-filtering technique that removes molecules such as myoglobin.

Frequently asked questions

What is rhabdo in rhabdomyolysis?

Rhabdo is simply the short name for rhabdomyolysis: the breakdown of skeletal muscle, with release of myoglobin, potassium and CK into the blood.

What are the early signs of rhabdomyolysis?

Muscle pain far worse than expected, weakness or being unable to finish a usual workout, and tea- or cola-colored urine, usually 1 to 3 days after the trigger. Swelling, nausea and passing less urine can follow.

What are the most common drugs causing rhabdomyolysis?

Statins and fibrates, especially in combination or with interacting drugs, are the most reported, although serious cases are rare. Antipsychotics, gabapentinoids, alcohol, cocaine and other stimulants are also linked to rhabdo.

What are the diagnostic criteria for rhabdomyolysis?

Most doctors use a CK level above five times the upper limit of normal (roughly 1,000 U/L), with a compatible history and symptoms; above 5,000 U/L is considered severe. Kidney tests, potassium and a urinalysis assess severity.

Can dehydration cause rhabdomyolysis?

Dehydration alone does not usually cause it, but it makes rhabdo worse by reducing the kidneys' ability to clear myoglobin. Combined with heat and hard exercise, it is a classic trigger.

How long does it take to recover from rhabdomyolysis?

Mild cases often improve within a few weeks to a month. CK returns to baseline about 6 to 10 days after its peak. Kidney injury, if present, can take longer, and a return to hard exercise should be gradual and cleared by a doctor.

Is rhabdomyolysis curable?

Yes. Most people recover fully, especially after exercise-related rhabdo treated early. The outlook is more serious when kidney failure develops or the cause is trauma, sepsis or cardiac arrest.

Sources

• MedlinePlus — Rhabdomyolysis — National Library of Medicine — medlineplus.gov
• National Institute for Occupational Safety and Health — Rhabdomyolysis and Work — CDC, 2024 — cdc.gov
• National Institute for Occupational Safety and Health — Reducing Risk for Rhabdomyolysis — CDC, 2024 — cdc.gov
• Cleveland Clinic — Rhabdomyolysis: What It Is, Causes, Symptoms and Treatment — Cleveland Clinic, 2023 — clevelandclinic.org
• MedlinePlus — Creatine phosphokinase test — National Library of Medicine — medlineplus.gov
• MedlinePlus — Potassium test — National Library of Medicine — medlineplus.gov
• MedlinePlus — Creatinine blood test — National Library of Medicine — medlineplus.gov
• MedlinePlus — Calcium blood test — National Library of Medicine — medlineplus.gov
• MedlinePlus — Phosphorus blood test — National Library of Medicine — medlineplus.gov
• Chavez LO et al. — Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice — Crit Care, 2016 — doi.org
• McMahon GM et al. — A risk prediction score for kidney failure or mortality in rhabdomyolysis — JAMA Intern Med, 2013 — doi.org
• Nelson DA et al. — Sickle Cell Trait, Rhabdomyolysis, and Mortality among U.S. Army Soldiers — N Engl J Med, 2016 — doi.org
• Graham DJ et al. — Incidence of hospitalized rhabdomyolysis in patients treated with lipid-lowering drugs — JAMA, 2004 — doi.org
• Nye NS et al. — Clinical Practice Guidelines for Exertional Rhabdomyolysis: A Military Medicine Perspective — Curr Sports Med Rep, 2021 — doi.org
• Safari S et al. — Incidence of Electrolyte Imbalances Following Traumatic Rhabdomyolysis: A Systematic Review and Meta-Analysis — Cureus, 2024 — doi.org
• Zaki HA et al. — Pediatric rhabdomyolysis: a systematic review and meta-analysis of etiologies, management, and outcomes — BMC Pediatr, 2025 — doi.org
• The Role of Urine Alkalinization in Preventing Rhabdomyolysis-Induced Acute Kidney Injury and Need for Dialysis: A Systematic Review and Meta-Analysis — Bull Emerg Trauma, 2025 — pubmed.ncbi.nlm.nih.gov
• Yajima W et al. — Association between initial intravenous fluid volume and the composite outcome of hemodialysis dependence at discharge or in-hospital mortality in inpatients with rhabdomyolysis — J Intensive Care, 2025 — doi.org
• Ahmadzadeh K et al. — The Value of Serum CK in Predicting Traumatic Rhabdomyolysis Induced Acute Kidney Injury: A Systematic Review and Meta-Analysis — Arch Acad Emerg Med, 2026 — pubmed.ncbi.nlm.nih.gov
• Forni L et al. — Hemoadsorption therapy for myoglobin removal in rhabdomyolysis: consensus of the hemoadsorption in rhabdomyolysis task force — BMC Nephrol, 2024 — doi.org
• Reynolds A et al. — Effects of CytoSorb hemoadsorption therapy on serum myoglobin and creatine kinase levels in severe rhabdomyolysis: a systematic review and meta-analysis — BMC Nephrol, 2026 — doi.org
• AlHumaidan HM et al. — From the Field to the Emergency Room: A Systematic Case-Level Review of Exertional Rhabdomyolysis and Acute Kidney Injury in Athletes — Cureus, 2026 — doi.org
• Liu M et al. — Gabapentinoids-Induced Rhabdomyolysis/Myopathy: Clinical Characteristics, Management, Outcomes, and Critical Safety Alerts — J Pain Res, 2025 — doi.org
• João RB et al. — CDK4/6 inhibitor-statin interaction and rhabdomyolysis in breast cancer treatment: a case-based systematic review — Cancer Chemother Pharmacol, 2026 — doi.org
• Wang QS et al. — Atypical Presentation of Exertional Rhabdomyolysis in Older Adults: Two Case Reports and Literature Review — Am J Case Rep, 2026 — doi.org
• Armed Forces Health Surveillance Division — Exertional rhabdomyolysis among U.S. active component service members, 2021-2025 — MSMR, 2026 — pubmed.ncbi.nlm.nih.gov
• Children's National Research Institute — Dexamethasone Addition to Standard Protocols for Non-Traumatic Rhabdomyolysis (NCT06429982) — ClinicalTrials.gov, 2024 — clinicaltrials.gov
• University of Salford — The Rhabdomyolysis Evaluation in the Emergency Department (REED) Score (NCT07158554) — ClinicalTrials.gov, 2026 — clinicaltrials.gov

Further reading

• Comprehensive metabolic panel: how to read it
• Electrolyte panel: what your results mean
• eGFR: what your kidney result means
• Blood urea nitrogen (BUN): high or low levels
• High BUN and creatinine: what your results mean
• AST blood test: liver and muscle enzyme explained
• Muscle loss, eGFR and the cystatin C test

Understand your lab results with AI DiagMe

After rhabdomyolysis, or when a routine test shows a high CK, you often receive a long report: CK, creatinine, potassium, calcium, phosphorus, liver enzymes and a urinalysis, sometimes repeated over several days. AI DiagMe reads your lab report in minutes, explains each result in plain language, shows what needs follow-up and suggests questions to ask your doctor. Upload your lab results to AI DiagMe for a clear, personal report.