Is bronchitis contagious?

In general, whether bronchitis is contagious depends on its cause. If it is caused by environmental irritants or foreign body aspiration, it is usually not contagious. However, if it results from bacterial, viral, or mycoplasma infection, it may be contagious. The specific analysis is as follows:

1. Not contagious

If bronchitis is caused by inhaling irritating gases or exposure to allergens leading to aseptic inflammation of the mucous membrane, it is generally not contagious because there is neither an infectious source nor a transmission route. Similarly, if improper eating leads to foreign body aspiration into the trachea, resulting in reduced tracheal function and inflammatory changes, cross-infection with others typically does not occur.

2. Contagious

First, bronchitis caused by bacterial infections such as *Mycobacterium tuberculosis*, *Streptococcus pneumoniae*, or *Bordetella pertussis* is somewhat contagious and can easily spread via respiratory droplets, causing cross-infection. Individuals with weakened immune systems are particularly susceptible. Second, bronchitis triggered by viral infections such as influenza virus or respiratory syncytial virus (RSV), which cause significant respiratory inflammation, is also highly transmissible due to the high viral load in the airways. Lastly, mycoplasma is a pathogenic microorganism distinct from bacteria and viruses. Infection often causes upper respiratory tract infections such as tracheobronchitis or pneumonia. This pathogen spreads easily through the air; therefore, bronchitis induced by mycoplasma infection is also contagious.

Patients with contagious bronchitis should avoid sharing personal items with others, refrain from frequenting public places during treatment, and wear masks to help reduce the risk of transmission.