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Bronchodilators are a type of medication that make breathing easier by relaxing the muscles in the lungs and widening the airways (bronchi).
They're often used to treat long-term conditions where the airways may become narrow and inflamed, such as:
Bronchodilators may be either:
Inhaled corticosteroids are the main treatment to reduce inflammation and prevent flare-ups in asthma.
But some people may also benefit from taking bronchodilators to keep the airways open and to enhance the effects of corticosteroids. Long-acting bronchodilators should never be taken without corticosteroids.
In COPD, initial treatment is with short- or long-acting bronchodilators, with corticosteroids added in some severe cases.
Treatment with corticosteroids and bronchodilators may require the use of separate inhalers, but increasingly these medications are provided together in single inhalers.
The three most widely used bronchodilators are:
Beta-2 agonists and anticholinergics are available in both short-acting and long-acting forms, whereas theophylline is only available in a long-acting form.
Beta-2 agonists are used for both asthma and COPD, although some types are only available for COPD. They're usually inhaled using a small, hand-held inhaler but may also be available as tablets or syrup.
For sudden, severe symptoms they can also be injected or nebulised. A nebuliser is a compressor used to turn liquid medication into a fine mist, allowing a large dose of the medicine to be inhaled through a mouthpiece or face mask.
Beta-2 agonists work by stimulating receptors called beta-2 receptors in the muscles that line the airways, which causes them to relax and allows the airways to dilate (widen).
They should be used with caution in people with:
In rare cases, beta-2 agonists can make some of the symptoms and possible complications of these conditions worse.
Anticholinergics (also known as antimuscarinics) are mainly used for COPD but a few are also licenced for asthma. They're usually taken using an inhaler but may be nebulised to treat sudden and severe symptoms.
Anticholinergics cause the airways to dilate by blocking the cholinergic nerves. These nerves release chemicals that can cause the muscles lining the airways to tighten.
They should be used with caution in people with:
In people with benign prostatic hyperplasia or a bladder outflow obstruction, anticholinergics can cause urination problems. Glaucoma can get worse if anticholinergic medication unintentionally gets into the eyes.
Theophylline is usually taken in tablet or capsule form, but a different version called aminophylline can be given directly into a vein (intravenously) if your symptoms are severe.
It's unclear exactly how theophylline works, but it seems to reduce any inflammation (swelling) in the airways, in addition to relaxing the muscles lining them.
The effect of theophylline is weaker than other bronchodilators and corticosteroids. It's also more likely to cause side effects, so is often only used alongside these medicines if they're not effective enough.
Theophylline should be used with caution in people with:
Theophylline may cause these conditions to get worse. In people with liver problems, it can sometimes lead to a dangerous build-up of medication in the body. Other medicines can also cause abnormal build-up of theophylline in the body and this should always be checked by your doctor.
Elderly people may also need additional monitoring while taking theophylline.
The side effects of bronchodilators can vary, depending on the specific medication you're taking. Make sure you read the leaflet that comes with your medication to see what the specific side effects are.
General side effects of bronchodilators include:
Read more about the side effects of bronchodilators.
In most cases, bronchodilators should be taken as normal while pregnant or breastfeeding.
However, speak to your GP if you regularly use bronchodilators and are considering having a baby or think you might be pregnant.
Pregnancy may affect your asthma, so it's important to continue taking your medication and have it monitored regularly, to ensure the condition is controlled.
Read more about taking medication during pregnancy.
Bronchodilators may interact with other medicines, which could affect the way they work or increase your risk of side effects.
Some of the medicines that can interact with bronchodilators (particularly theophylline) include:
This isn't a complete list of all the medications that can interact with bronchodilators, and not all of these interactions apply to each type of bronchodilator.
You should always carefully read the patient information leaflet (PIL) that comes with your medication. You may be able to find a specific PIL in the MHRA database on GOV.UK.
If in doubt, speak to your pharmacist or GP.
Bronchodilators can sometimes cause side effects, although these are usually mild or short-lived.
Some of the main side effects of bronchodilators are described below, but this isn't an exhaustive list. They may not all apply to the specific medication you're taking.
For information on the side effects of a particular bronchodilator, check the patient information leaflet (PIL) that comes with your medication. You may be able to find a specific PIL in the MHRA database on GOV.UK.
The main side effects of beta-2 agonists such as salbutamol include:
These side effects often improve and disappear completely after you've been using beta-2 agonists for a few days or weeks. Contact your GP if your side effects persist, as your dose may need to be adjusted.
More serious side effects are rare, but can include sudden constriction of the airways (paradoxical bronchospasm) with some inhalers. Excessive doses occasionally causing heart attacks and a severely low level of potassium in the blood (hypokalemia).
The main side effects of anticholinergics like ipratropium include:
Less common side effects include:
Glaucoma may worsen if the medication gets in the eyes when using an inhaler or a nebuliser.
Theophylline can cause serious side effects if too much of it builds up in your body. You'll usually need to have regular blood tests during treatment to ensure the levels of theophylline in your body are safe.
Older people are more at risk of developing side effects from theophylline, because their livers may not be able to remove it from their body.
The main side effects of theophylline include:
Contact your GP if you have any of these side effects, as your dose may need to be reviewed.