What Are the Main Causes of Bronchitis?

What is bronchitis?

The main causes of bronchitis are smoking, air pollution, dust, toxic gases, or due to a viral or bacterial infection.
The main causes of bronchitis are smoking, air pollution, dust, toxic gases, or due to a viral or bacterial infection.

Bronchitis occurs when the bronchial tubes, the airways that carry air to the lungs, become irritated and inflamed. When they are inflamed, they produce excess mucus and cause coughing. Acute bronchitis, which is sometimes called a chest cold, can develop after a cold or upper respiratory infection. Acute bronchitis will usually get better on its own but can sometimes develop into pneumonia.

Bronchitis affects the airways leading to the lungs, while pneumonia affects the air sacs in the lungs, called alveoli. Pneumonia is much worse than bronchitis and can be life-threatening in older or otherwise vulnerable people. Pneumonia symptoms are similar to bronchitis symptoms but generally are more severe.

Chronic bronchitis is caused by irritation of the airways, usually from smoking or exposure to other irritants such as toxic gases. Chronic bronchitis is one of the conditions classified as a chronic obstructive pulmonary disease (COPD) and needs to be managed by a doctor.

Signs and symptoms of bronchitis

Acute bronchitis usually starts with a cold and can include the following symptoms:

Types of bronchitis

One of the main differences between acute bronchitis and chronic bronchitis is how long the problem lasts.

Acute bronchitis

Acute bronchitis generally lasts up to two weeks, though the cough associated with it may last for up to two months. It doesn't cause any lasting effects.

Chronic bronchitis

Chronic bronchitis involves long-term inflammation. To be diagnosed with chronic bronchitis, you must have a productive cough and mucus that lasts for more than three months a year with episodes recurring for at least two years in a row.

Causes of bronchitis

Acute bronchitis and chronic bronchitis have different causes.

Acute bronchitis

The most common cause of acute bronchitis is a viral infection, such as those that cause influenza and the common cold. Occasionally, acute bronchitis is caused by a bacterial infection. In either case, bronchitis occurs when the bronchial tubes become inflamed and start producing mucus.

Acute bronchitis is contagious, so you should take precautions to avoid spreading it to others. This includes:

  • Washing hands thoroughly
  • Covering your mouth when you cough
  • Staying away from others when you are sick

Chronic bronchitis

Chronic bronchitis is a constant irritation and inflammation of the bronchial tubes that is usually caused by smoking. Exposure to air pollution, dust, and toxic gases can also cause chronic bronchitis. Chronic bronchitis is generally not contagious because it is not caused by a virus or bacteria.

When to see the doctor for bronchitis

Most cases of acute bronchitis can be treated at home. Antibiotics do not usually help bronchitis. You should see your doctor for any of the following:


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Diagnosing bronchitis

Your doctor will probably be able to diagnose acute bronchitis by listening to your symptoms and doing a physical exam. Blood tests are not used to diagnose bronchitis, but doctors may order one if they think you have another infection. If you have a fever, your doctor may order a chest X-ray to make sure you don't have pneumonia. Additionally, your doctor may test a sample of your sputum, the mucus that you cough up, to see if you have another type of infection.

To diagnose chronic bronchitis, your doctor may do a pulmonary function test to check your lung function. During a pulmonary function test, your doctor will use a spirometer, which is a device that you blow into, to find out how much air your lungs can hold and how quickly you can get air out of your lungs.

Treatments for bronchitis

Acute bronchitis will likely improve without medication, so most treatment focuses on relieving the symptoms. You can feel better by:

  • Getting lots of rest
  • Drinking plenty of fluids, especially hot liquids such as tea
  • Taking honey to help with cough (don’t give to babies younger than 1)
  • Using sinus rinses or saline nasal sprays
  • Using lozenges to help with a sore throat (don’t give to children under 4)
  • Using a humidifier or inhaling steam from a shower
  • Taking over-the-counter pain medicine such as ibuprofen or acetaminophen

Chronic bronchitis cannot be cured, but your doctor may manage your symptoms with a combination of the following methods:

  • Oxygen therapy
  • Pulmonary rehabilitation, which includes cardiovascular exercises
  • A mucus-clearing device
  • Anti-inflammatory drugs such as corticosteroids
  • Drugs called bronchodilators that help your airways stay open

Health Solutions From Our Sponsors

American Family Physician: "Acute Bronchitis."

Centers for Disease Control and Prevention: "Chest Cold (Acute Bronchitis)."

Centers for Disease Control and Prevention: "Preventing and Treating Bronchitis."

Johns Hopkins Medicine: "Acute Bronchitis."

Johns Hopkins Medicine: "Chronic Bronchitis."

MedlinePlus: "Acute Bronchitis."

Merck Manual: "Acute Bronchitis."

National Heart, Lung, and Blood Institute: "Pneumonia."