Bronchitis is an infection of the main airways of the lungs (bronchi), causing them to become irritated and inflamed.
The bronchi branch off on either side of your windpipe (trachea). They lead to smaller and smaller airways inside your lungs, known as bronchioles.
The walls of the bronchi produce mucus to trap dust and other particles that could otherwise cause irritation.
Most cases of bronchitis develop when an infection irritates and inflames the bronchi, causing them to produce more mucus than usual. Your body tries to shift this extra mucus through coughing.
Bronchitis can be described as being either:
It's important that you stop smoking if you smoke and you have bronchitis.
Cigarette smoke and the chemicals in cigarettes make bronchitis worse and increase your risk of developing chronic bronchitis and COPD.
This page covers:
The main symptom of acute bronchitis is a hacking cough, which may bring up clear, yellow-grey or greenish mucus (phlegm). Other symptoms are similar to those of the common cold or sinusitis, and may include:
If you have acute bronchitis, your cough may last for several weeks after other symptoms have gone. You may also find that the continual coughing makes your chest and stomach muscles sore.
Some people may experience shortness of breath or wheezing, due to inflamed airways. However, this is more common with long-term (chronic) bronchitis.
Most cases of acute bronchitis can be easily treated at home with rest, non-steroidal anti-inflammatory drugs (NSAIDs) and plenty of fluids.
You only need to see your GP if your symptoms are severe or unusual – for example, if:
Your GP may need to rule out other lung infections, such as pneumonia, which has symptoms similar to those of bronchitis. If your GP thinks you may have pneumonia, you'll probably need a chest X-ray, and a sample of mucus may be taken for testing.
If your GP thinks you might have an underlying condition, they may also suggest that you have a lung function test. You'll be asked to take a deep breath and blow into a device called a spirometer, which measures the volume of air in your lungs. Decreased lung capacity can indicate an underlying health problem.
Bronchitis can be caused by either a virus or bacteria, although viral bronchitis is much more common.
In most cases, bronchitis is caused by the same viruses that cause the common cold or flu. The virus is contained in the millions of tiny droplets that come out of the nose and mouth when someone coughs or sneezes.
These droplets typically spread about 1m (3ft). They hang suspended in the air for a while, then land on surfaces where the virus can survive for up to 24 hours. Anyone who touches these surfaces can spread the virus further by touching something else.
Read more about how cold and flu germs spread.
Bronchitis can also be triggered by breathing in irritant substances, such as smog, chemicals in household products or tobacco smoke.
Smoking is the main cause of chronic bronchitis, and it can affect people who inhale second-hand smoke, as well as those who smoke themselves. People with chronic bronchitis often develop another smoking-related lung disease called emphysema – where the air sacs inside the lungs become damaged, causing shortness of breath.
If you smoke, you should stop immediately because is aggravates bronchitis and increases your risk of developing emphysema. Stopping smoking while you have bronchitis can also be the perfect opportunity to quit altogether.
Read more about stop smoking treatments.
You may also be at risk of developing chronic bronchitis and other types of chronic obstructive pulmonary disease (COPD) if you're often exposed to materials that can damage your lungs, such as:
This is sometimes known as "occupational bronchitis", and it usually eases once you're no longer exposed to the irritant substance.
Read more about the causes of COPD.
You can also read the Health and Safety Executive's 2014 report on Work-related COPD in Great Britain (PDF, 58kb).
In most cases, acute bronchitis will clear up by itself within a few weeks without the need for treatment. In the meantime, you should drink lots of fluid and get plenty of rest (see below).
In some cases, the symptoms of bronchitis can last much longer. If symptoms last for at least three months, it's known as "chronic bronchitis". There's no cure for chronic bronchitis, but some lifestyle changes can help ease your symptoms, such as:
There are several medications to relieve symptoms. Bronchodilators and steroids "open up" the airways and can be prescribed as an inhaler or as tablets. Mucolytic medicines thin the mucus in the lungs making it easier to cough up.
If you have acute bronchitis:
There's little evidence that cough medicines work – read more about treating coughs.
The Medicines and Healthcare Products Regulatory Agency (MHRA) has recommended that over-the-counter cough medicines shouldn't be given to children under the age of six. Children aged 6 to 12 should only use them on the advice of a doctor or pharmacist.
As an alternative to an over-the-counter cough medicine, try making your own mixture of honey and lemon, which can help soothe a sore throat and ease your cough.
Antibiotics aren't routinely prescribed for bronchitis because it's normally caused by a virus. Antibiotics have no effect on viruses, and prescribing them when they're unnecessary can, over time, make bacteria more resistant to antibiotic treatment. Read more about antibiotic resistance.
Your GP will only prescribe antibiotics if you have an increased risk of developing complications, such as pneumonia. Antibiotics may also be recommended for:
If you're prescribed antibiotics for bronchitis, it's likely to be a five-day course of amoxicillin or doxycycline. Side effects of these drugs are uncommon, but include nausea, vomiting and diarrhoea.
Pneumonia is the most common complication of bronchitis. It occurs when the infection spreads further into the lungs, causing the tiny air sacs inside the lungs to fill up with fluid. About 1 in 20 cases of bronchitis lead to pneumonia.
People at an increased risk of developing pneumonia include:
Mild pneumonia can usually be treated with antibiotics at home. More severe cases may require admission to hospital.