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Bronchodilator medicines

Bronchodilator medicines, or bronchodilators, make breathing easier by relaxing the muscles in the lungs and widening the airways (bronchi).

They are often used to treat long-term conditions where the airways become intermittently narrow and inflamed, such as:

Types of bronchodilator

There are two main types of bronchodilator medication:

  • short-acting bronchodilators – which are used as short-term relief from sudden, unexpected attacks of breathlessness 
  • long-acting bronchodilators – which have longer-lasting effects and, if used regularly, can not only help control breathlessness in asthma and COPD, but also increase the effectiveness of corticosteroids in asthma (see below)

The three most widely used bronchodilators are beta-2 agonists, anticholinergics and theophylline. 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.

For asthma, inhaled corticosteroids are the most important regular treatment to reduce inflammation and prevent flare-ups, but some people may benefit from taking additional long-acting 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 both corticosteroids and bronchodilators may require the use of separate inhalers, but increasingly these medications are provided together in single inhalers.

Beta-2 agonists

Beta-2 agonists such as salbutamol, salmeterol, formoterol and vilanterol are usually inhaled using a small, hand-held inhaler. They are used for both asthma and COPD, although some types, such as indacaterol, are only available for COPD.

While not the most efficient way to take them, some of these medications are also available as tablets or syrup. For sudden, severe symptoms they can also be injected or nebulised. This is where a compressor is used to turn liquid medication into a fine mist, allowing a large dose of the medicine to be inhaled through a mouthpiece or a 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).


Anticholinergics (also known as antimuscarinics) – such as ipratropium, tiotropium, aclidinium and glycopyrronium – are usually taken using an inhaler. For sudden and more severe symptoms, some of them can also be administered using a nebuliser. They are mainly used for COPD. 

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.


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 is unclear exactly how theophylline works, but it seems to reduce any inflammation (swelling) in the airways, in addition to relaxing the muscles lining them.

Compared with other bronchodilators and corticosteroids, the effect of theophylline is rather weak. It is also more likely to cause side effects, so is often only used alongside these medicines if they are not effective enough.

Side effects

The side effects of bronchodilators can vary, depending on the specific medication you are taking, so make sure you read the leaflet that comes with your medication to see what the specific side effects are.

Alternatively, you can search for your medication in our medicines A-Z guide.

General side effects of bronchodilators include:

Read more about the side effects of bronchodilators.


Most people can take bronchodilators safely if they need them, although the benefits of treatment will need to be weighed against the potential risks.

For example, bronchodilators can cause more problems if you have cardiovascular disease, diabetes, an overactive thyroid (hyperthyroidism) or high blood pressure (hypertension). If you have one of these conditions and are prescribed bronchodilator medication, it’s important to discuss potential problems with your doctor and to be on the lookout for them.

Bronchodilators are generally safe to use while pregnant or breastfeeding, but you should speak to your GP if you regularly use bronchodilators and you are considering having a baby, or think you may be pregnant.

Bronchodilators, especially theophylline, can also affect certain other medications you may be taking, so let your doctor know about any other medicines you are on before starting treatment. In addition to this, check with your GP or pharmacist before taking new medications while on bronchodilators.

Read more about the cautions and interactions of bronchodilators.

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