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:
- asthma – a common lung condition caused by inflammation of the airways
- chronic obstructive pulmonary disease (COPD) – a lung disease usually caused by smoking which causes blockage of the airways, although this can be partially reversed with treatment
Bronchodilators may be either:
- short-acting – used as short-term relief from sudden, unexpected attacks of breathlessness
- long-acting – used regularly, to help control breathlessness in asthma and COPD and increase the effectiveness of corticosteroids in asthma (see below)
Bronchodilators and corticosteroids
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.
Types of bronchodilator
The three most widely used bronchodilators are:
- beta-2 agonists – such as salbutamol, salmeterol, formoterol and vilanterol
- anticholinergics – such as ipratropium, tiotropium, aclidinium and glycopyrronium
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:
- an overactive thyroid (hyperthyroidism) – a condition that occurs when there’s too much thyroid hormone in the body
- cardiovascular disease – any disease of the heart or blood vessels
- an irregular heartbeat (arrhythmia)
- high blood pressure (hypertension)
- diabetes – a lifelong condition that causes a person’s blood sugar level to become too high
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:
- 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 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:
- 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. 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.
What are the side effects of bronchodilators?
Side effects of bronchodilators vary depending on the type of bronchodilator.
Beta-adrenergic bronchodilators side effects
Common side effects of beta-adrenergic bronchodilators include:
- Migraine headaches
- Non-migraine headaches
- Stomach upset
- Flu-like symptoms
- Cold symptoms
- Ear infections (otitis media)
Other side effects of beta-adrenergic bronchodilators include:
- Allergic reactions (rash, hives, itching)
- Increased sputum
- Shortness of breath
Possible serious side effects of beta-adrenergic bronchodilators include:
- Bronchospasm (worsening of asthma)
- Serious allergic reactions (anaphylaxis)
- Low potassium
- Abnormal heart rhythm (palpitations)
- Fast heart rate
- Elevated blood pressure
- Chest pain
Anticholinergic bronchodilators side effects
Common side effects of anticholinergic bronchodilators include:
Other side effects of anticholinergic bronchodilators include:
Possible serious side effects of anticholinergic bronchodilators include:
- Life-threatening bronchospasms
- Serious allergic reactions involving the closure of the airways.
- Worsening symptoms of benign prostatic hyperplasia
- Worsening symptoms of narrow-angle glaucoma
Xanthines side effects
Common side effects of xanthines include:
Other side effects of xanthines include:
Possible serious side effects of xanthines include:
Which drugs or supplements interact with bronchodilators?
Drug interactions of beta-adrenergic bronchodilators
- Tricyclic antidepressants, for example, amitriptyline (Elavil, Endep), and monoamine oxidase inhibitors (MAOIs), for example, tranylcypromine, should not be combined with beta-adrenergic bronchodilators because of their additive effects on the vascular system (for example, increased blood pressure and/or heart rate). A period of two weeks should elapse between treatment with beta-adrenergic bronchodilators and tricyclic antidepressants or monoamine oxidase inhibitors.
- Use of beta-adrenergic bronchodilators with other stimulant medications is discouraged because of their combined effects on heart rate, blood pressure, and the potential for causing chest pain in patients with underlying coronary heart disease.
- Beta-blockers, for example, propranolol (Inderal, Inderal LA), block the effect of beta-adrenergic bronchodilators and may induce bronchospasm in asthmatics.
- Beta-adrenergic bronchodilators may cause hypokalemia (low potassium). Therefore, combining beta-adrenergic bronchodilators with loop diuretics, for example, furosemide (Lasix), may increase the likelihood of hypokalemia.
Drug interactions of anticholinergic bronchodilators
- Use with other anticholinergic drugs (for example, atropine) may increase the occurrence of side effects.
Drug interactions of xanthine bronchodilators
- Allopurinol (Zyloprim), cimetidine (Tagamet), ciprofloxacin (Cipro), clarithromycin (Biaxin), itraconazole (Sporanox), ketoconazole, erythromycin, oral contraceptives, fluvoxamine (Luvox), ephedrine, and propranolol (Inderal) elevate theophylline blood levels and can lead to toxicity. Theophylline toxicity causes nausea, vomiting, insomnia, seizures, agitation, and life- threatening heart rhythm abnormalities.
- St. John’s Wort, rifampin, and carbamazepine decrease levels of theophylline and potentially its effect by increasing its elimination.
- Theophylline may decrease levels and the effect of carbamazepine by increasing its elimination. Theophylline is metabolized mainly by the liver and dosages should be reduced in patients with liver dysfunction. On the other hand, theophylline is generally metabolized more rapidly in smokers (both tobacco and marijuana) and higher dosages may be required.
Are bronchodilators safe to use during pregnancy or while breastfeeding?
- Beta-adrenergic bronchodilators are used for treating children. However, there are no adequate studies of beta-adrenergic bronchodilator use during pregnancy. Some reports indicate that albuterol sulfate may cause congenital defects when used during pregnancy.
- It’s not known whether beta-adrenergic bronchodilators are excreted in breast milk.
- The safety of anticholinergic bronchodilators in pregnant women or nursing mothers has not been adequately evaluated.
- Xanthine bronchodilators have not been adequately studied in pregnant women. Theophylline is excreted in breast milk and may cause mild side effects such as irritability in the infant.
- The risks to the fetus or breast-feeding infant versus the risk to the woman should be considered before using bronchodilators in pregnant women; consultation with the patient’s OB/GYN doctor may be advisable.
Are there differences between bronchodilators?
Bronchodilators differ in their mechanism of action, how quickly they work, and their duration of action, their uses, side effects, and how they are administered. Beta-adrenergic bronchodilators are supplied as aerosols for inhalation, powders for inhalation, solution for nebulization, syrup, and tablets. Anticholinergic bronchodilators are supplied as solutions for inhalation, powder for inhalation, and nebulized solution. Xanthines are supplied as tablets, capsules, elixir, and solution for injection.