Is Legionnaires' disease contagious from person to person?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Legionnaires' disease is not typically contagious and does not usually spread from person to person. Instead, people become infected by inhaling small water droplets (aerosols) containing Legionella bacteria. Common sources include contaminated hot tubs, cooling towers, plumbing systems, decorative fountains, and humidifiers. In rare cases, transmission may occur through drinking water that accidentally enters the lungs.

If you're experiencing symptoms like cough, fever, shortness of breath, or muscle aches—especially after exposure to a possible water source—it's important to act quickly. Legionnaires' disease can mimic other respiratory illnesses, making early identification essential. Take a free, instant, online symptom check to better understand what may be causing your symptoms and get clear guidance on your next steps.

Reviewed for medical accuracy: 07/20/2026

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Explanation

Legionnaires' disease is an illness caused by the Legionella bacteria. People usually get it by breathing in tiny water droplets that have the bacteria in them. This can happen from things like air conditioning systems, hot tubs, or showers. If you're experiencing respiratory symptoms and want to understand what might be causing them, you can use a free symptom checker to help identify potential conditions.

Not Contagious: The disease is not generally spread from one person to another. This means if someone has Legionnaires' disease, they usually can't give it to you by coughing or sneezing.
Rare Cases: There are very rare instances where person-to-person spread has been suspected, but these are extremely uncommon.

In summary, while Legionnaires' disease can be serious, it is not something you typically catch from another person. It is important to ensure that water systems are clean to prevent the bacteria from growing and spreading.

(References)

Berbecar S. (1997). [Legionellosis: clinical and epidemiological data]. Bacteriologia, virusologia, parazitologia, epidemiologia (Bucharest, Romania : 1990), 9235133.
Breiman RF, & Butler JC. (1998). Legionnaires' disease: clinical, epidemiological, and public .... Seminars in respiratory infections, 9643385.
McGinnis S, Free RJ, Burnell J, Basavaraju SV, Kanaskie T, Hannapel EJ, et al. (2023). Suspected Legionella Transmission from a Single Donor to .... American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, 37914432.

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