Bronchodilator medicines

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.

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.

Cautions and interactions

Not all bronchodilators are suitable for everyone, as they can cause problems if you have other health conditions or take them alongside other medications.

Health conditions

If you have one of the health conditions listed below, bronchodilator medicines should be used with caution.

This doesn’t mean you cannot take these medications, but you will need to be aware of the potential problems that could develop and be on the lookout for them. You may also need to be regularly monitored by your GP during treatment, so they can check for any problems.

Beta-2 agonists

Beta-2 agonists 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 and, in the case of diabetes, can lead to a serious complication called ketoacidosis (where by-products called ketones build up in the body).


Anticholinergics should be used with caution in people with:

  • benign prostatic hyperplasia  a non-cancerous swelling of the prostate
  • a bladder outflow obstruction  any condition that affects the flow of urine out of the bladder, such as bladder stones or prostate cancer
  • glaucoma  a build-up of pressure in the eye

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 should be used with caution in people with:

  • an overactive thyroid
  • cardiovascular disease
  • liver problems – such as liver disease
  • high blood pressure
  • stomach ulcers  open sores that develop on the stomach lining
  • epilepsy  a condition that affects the brain and causes repeated seizures (fits)

Theophylline may cause these conditions to get worse and, in people with liver problems, 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.

Pregnancy and breastfeeding

In most cases, bronchodilators  particularly those that are inhaled  can and 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 is important that you continue to take your medication and have it monitored regularly, to ensure the condition is controlled.

Read more about taking medication during pregnancy.

Interactions with other medicines

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:

  • some diuretics  a type of medication that helps remove fluid from the body
  • some antidepressants – including monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs)
  • digoxin  a medication used to treat arrhythmias
  • benzodiazepines  a type of sedative that may sometimes be used as a short-term treatment for anxiety or sleeping problems (insomnia)
  • lithium  a medication used to treat severe depression and bipolar disorder
  • quinolones  a type of antibiotic medication

This is not an exhaustive 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 make sure you carefully read the patient information leaflet (PIL) that comes with your medication to see if there are other medications you should avoid. Online versions of many PILs can be found in our medicines A-Z guide.

If in doubt, speak to your pharmacist or GP.

Side effects of bronchodilator medicines

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 is not an exhaustive list and they may not all necessarily apply to the specific medication you are taking.

For information on the side effects of a particular bronchodilator, check the information leaflet that comes with your medication, or search for your medication in our medicines A-Z guide.

Beta-2 agonists

The main side effects of beta-2 agonists include:

  • trembling, particularly in the hands
  • nervous tension
  • headaches
  • suddenly noticeable heartbeats (palpitations)
  • muscle cramps

These side effects will often improve and disappear completely after you have 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, with excessive doses occasionally causing heart attacks and a severely low level of potassium in the blood (hypokalemia).


The main side effects of anticholinergics include:

Less common side effects include nausea, heartburn, difficulty swallowing (dysphagia), palpitations, throat irritation and difficulty urinating. 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 the medication builds up in your body. You will 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 the medication 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.