Is Bronchitis Viral or Bacterial?

Kenneth Knowles, MD
Medically reviewed by Kenneth Knowles, MDApril 30th, 2021
cough in public with mask

Bronchitis can be viral or bacterial. Acute bronchitis, however, is typically viral and caused by the same viruses that lead to common colds and influenza (flu). That said, it is possible to have viral and bacterial bronchitis at the same time. In addition to lab tests, sputum or mucus from a cough can be visually examined to determine whether bronchitis is viral, bacterial, or both. Clear or white mucus often indicates a viral infection, while yellow or green mucus may suggest a bacterial infection. The biggest difference between viral and bacterial bronchitis is treatment, as antibiotics used to treat bacterial infections don’t kill viruses. Let’s take a closer look at the different forms of bronchitis and common causes.

Types of Bronchitis

Plot twist: There is more than one type of bronchitis, but don’t let this confuse you! Understanding the different types of bronchitis will help you understand the causes (viral, bacterial, or environmental) and well as your risk factors:

  • Acute bronchitis (short-term viral or bacterial). We briefly covered this type of bronchitis when addressing our opening question, so we’ll keep this short: Acute bronchitis is a short-term illness and the most common form of bronchitis. It’s prominently caused by viral infections (though it may be caused by bacterial infections) and can last up to 90 days.
  • Infectious bronchitis (short-term bacterial or viral). This form of bronchitis can be viral or bacterial. While it’s typically caused by a virus, the viral infection can lead to the irritation of the bronchi, develop into a bacterial infection, and continue to cause symptoms even after the viral infection has passed. For example, acute bronchitis can often become bacterial following an upper respiratory infection (viral).
  • Irritative bronchitis (short-term environmental or industrial). Irritative bronchitis is typically caused by exposure to industrial or environmental irritants. These can include dust, fumes from strong chemicals/acids, ammonia, chlorine, organic solvents, etc.
  • Chronic bronchitis (long-term environmental or industrial). This is a long-term and more critical type of irritative bronchitis that develops over time. More often than not, chronic bronchitis is caused by smoking tobacco. It’s triggered by inflammation and irritation of the bronchial tubes, which causes mucus to thicken and can quickly lead to shortness of breath.

Causes of Bronchitis

Acute and infectious bronchitis are the two most common forms of infection. They are typically caused by:

Viral Infections

Viruses are by far the most common cause of acute bronchitis. From the common cold to influenza, any viral infection that produces an influx of mucus can irritate the bronchial tubes and lead to bronchitis.

Bacterial Infections

Bordetella pertussis is the most common form of bacterial infection that can lead to whooping cough and bacterial bronchitis. Acute bronchitis that is caused by a viral infection can also evolve into a bacterial infection. This happens when excess mucus produced by the virus infects the bronchial tubes. This can sometimes progress to pneumonia if the infection travels to the alveoli (air sacs in the lungs).

Sinus Infections, Allergies & Irritating Substances

Upper respiratory irritants triggered by chronic sinus infections, allergies, or environmental/industrial substances can lead to bronchitis. Exposure to these irritants can trigger the same symptoms of viral or bacterial infections, increasing mucus production and irritating the bronchial tubes.

Risk Factors & Treatment

Acute bronchitis doesn’t usually lead to serious complications, but it can become critical if a patient has chronic obstructive pulmonary disease (COPD) or emphysema. Individuals with asthma can also be at risk, as the infection can interfere with one’s ability to breathe effectively. If you know you’re at risk of developing complications from bronchitis, it’s extremely important to have access to a care provider at the onset of the infection’s symptoms to better manage any exacerbations. That’s where DispatchHealth comes in. We are an on-demand healthcare service that delivers medical care to patients in their homes. Once contacted our teams will come to your place of need, prepared with medical kits to address your exacerbations. Best of all, our service is affordable—we’re in-network with most insurances, including Medicare and Medicaid.

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If you’re experiencing a life-or-limb-threatening emergency or time-sensitive injury or illness, please call 911 or visit the emergency room immediately.


DispatchHealth relies only on authoritative sources, including medical associations, research institutions, and peer-reviewed medical studies.

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