What are the severe complications of Legionnaires' disease?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Legionnaires' disease is a severe form of pneumonia that can lead to serious complications if not treated promptly. Key complications include:

Respiratory failure: The lungs may lose the ability to deliver enough oxygen to the body.
Kidney failure: Kidneys can stop filtering waste from the blood effectively.
Rhabdomyolysis: Rapid muscle breakdown that releases harmful proteins into the bloodstream.
Septic shock: A sudden, dangerous drop in blood pressure that reduces blood flow to vital organs.

Because these complications can progress quickly and become life-threatening, early recognition of symptoms is critical. If you're experiencing cough, fever, muscle aches, or shortness of breath, don't wait to find out what's going on. Take a free, instant, online symptom check to better understand your symptoms, identify possible causes, and confidently plan your next steps toward the right care.

Reviewed for medical accuracy: 07/20/2026

Important Next Steps

Learn if Legionnaires’ disease could explain symptoms Discover likely causes of fever and cough See if your symptoms need urgent care Find OTC relief for fever and cough Find a doctor for pneumonia and infection Discover home remedies for pneumonia symptoms Understand if symptoms suggest severe Legionnaires’ disease

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Explanation

Legionnaires' disease is a type of pneumonia caused by bacteria. It can lead to serious health problems if not treated properly. Some of the severe complications include:

Rhabdomyolysis: This is when muscles break down too quickly, which can lead to kidney damage. It's a serious condition that needs medical attention.
Respiratory Failure: This happens when the lungs can't get enough oxygen into the blood. It can make it very hard to breathe and might need treatment in a hospital.
Kidney Problems: The kidneys might not work right if they are affected by the disease. This can happen because of the muscle breakdown or the infection itself.

These complications can be very serious, so it's important to see a doctor if you have symptoms of Legionnaires' disease. If you're experiencing concerning symptoms, you can check your symptoms with a free AI-powered assessment to help determine your next steps. Early treatment can help prevent these problems.

(References)

Kao AS, Herath CJ, Ismail R, & Hettiarachchi ME. (2022). The Triad of Legionnaires' Disease, Rhabdomyolysis, and .... The American journal of case reports, 35655418.
Rupasinghe S, & Lemoh C. (2025). Legionella pneumonia complicated with severe acute .... Journal of medical case reports, 40653483.
Takayanagi N, Ishiguro T, Matsushita A, Yoshii Y, Kagiyama N, Miyahara Y, et al. (2009). [Severe complications and their outcomes in 65 patients .... Nihon Kokyuki Gakkai zasshi = the journal of the Japanese Respiratory Society, 19637795.

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