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:
- acute bronchitis – temporary inflammation of the airways, causing a cough and mucus production, lasting up to three weeks; acute bronchitis can affect people of all ages but mostly affects children under the age of five; it's more common in winter and often develops following a common cold ↗, sore throat ↗ or flu ↗
- chronic bronchitis – a daily productive cough that lasts for three months of the year and for at least two years in a row; chronic bronchitis is one of a number of lung conditions, including emphysema ↗, that are collectively known as chronic obstructive pulmonary disease (COPD); ↗ it mostly affects adults over 40
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.
Symptoms of bronchitis
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:
- sore throat
- headache ↗
- runny or blocked nose
- aches and pains
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.
When to see your GP
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 cough is severe or lasts longer than three weeks
- you have a constant fever of 38C (100.4F) or above, for more than three days – this may be a sign of flu or a more serious condition, such as pneumonia ↗
- you cough up mucus streaked with blood
- you have an underlying heart or lung condition, such as asthma ↗, heart failure ↗ or emphysema ↗
- you're breathing rapidly (more than 30 breaths a minute) or develop chest pains ↗
- you become drowsy or confused
- you've had repeated episodes of bronchitis
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.
Causes of bronchitis
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 ↗.
Breathing in irritant substances
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 secondhand 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:
- grain dust
- textiles (fabric fibres)
- strong acids
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 ↗.
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:
- eating a healthy diet ↗can help prevent lung infections
- regular moderate exercise ↗ plus a healthy diet will help you to maintain a healthy weight – being overweight makes breathing harder
- avoiding smoking ↗ and smoky environments
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.
Managing symptoms at home
If you have acute bronchitis:
- get plenty of rest
- drink lots of fluid – this helps prevent dehydration ↗ and thins the mucus in your lungs, making it easier to cough up
- treat headaches, fever, and aches and pains with paracetamol ↗ or ibuprofen ↗ – although ibuprofen isn't recommended if you have asthma
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:
- premature babies
- elderly people over the age of 80
- people with a history of heart, lung, kidney or liver disease
- people with a weakened immune system, which could be the result of an underlying condition or a side effect of a treatment such as steroid medication
- people with cystic fibrosis ↗
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.
Complications of bronchitis
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:
- elderly people
- people who smoke
- people with other health conditions, such as heart, liver or kidney disease
- people with a weakened immune system
Mild pneumonia can usually be treated with antibiotics at home. More severe cases may require admission to hospital.