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How Do Inhaled Corticosteroids Work?

Inhaled corticosteroids (ICS) are used to treat people with asthma. Using ICS helps prevent asthma attacks (exacerbations) in people with persistent asthma. People with persistent asthma:1

  • Have symptoms more than twice weekly
  • Wake up more than 3 times monthly due to asthma
  • Use rescue inhalers more than twice weekly
  • Have limited activity due to asthma

Using ICS regularly helps people with asthma have fewer symptoms and exacerbations, and a better quality of life.1

What are inhaled corticosteroids?

The use of ICS treats symptoms of asthma. Taking ICS consistently decreases inflammation in the airways and prevents asthma exacerbations. ICS should not be used to treat acute asthma attacks (exacerbations). ICS drugs are considered the most effective long-term drugs to manage asthma.2

Some common ICS drugs include:2

For some people, the use of ICS is enough to prevent exacerbations. Other people need to add other medicines to control asthma, such as a short-acting beta-agonists (SABAs), long-acting beta-agonists (LABAs), or leukotriene receptor antagonists.1

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How do inhaled corticosteroids work for asthma?

Taking ICS reduces inflammation in the airways of the lungs. This causes:1

How can inhaled corticosteroids be taken?

ICS drugs are administered by inhalation, which helps the drug go directly to the airways. Using an inhaled medicine allows for the use of a lower dose and causes fewer side effects.1

ICS drugs can also be administered in several ways:1

  • Metered-dose inhaler (MDI): The drug is inhaled by taking 1 or more puff(s) as directed. MDIs are portable and convenient, and have a dose counter to keep track of remaining doses. Some people, especially children, use a mask/spacer with MDIs to help deliver the medicine.
  • Dry powder inhaler: The inhaler contains capsules with dry powder inside. When the inhaler is used, the capsule opens and the dry powder is inhaled. These are also portable and convenient, and have a dose counter.
  • Nebulizer: The medicine comes in a liquid solution for nebulization. One dose of the solution is emptied into the nebulizer machine before each use. The person wears a mask while the medicine is delivered over 10 to 15 minutes. This is the least portable option.

Your doctor will determine the administration method based on what you prefer and what you will have the most success with. For example, if you are always on the go, an MDI or dry powder inhaler is more convenient than a nebulizer.

For young children, a nebulizer or MDI with a spacer is recommended for better delivery of medicine.1

Side effects of inhaled corticosteroids

The most common side effects of ICS include:1,3

Other potential side effects from ICS use for asthma may occur. These are rare and may include:3

  • Cataracts/glaucoma
  • Suppression of the hypothalamic-pituitary-adrenal axis. This can suppress the immune system, making people who take ICS more susceptible to bacterial, fungal, and viral infections. Serious or fatal courses of measles or chickenpox can occur.
  • Increased blood sugar
  • Increased risk of bone fracture

These are not all the possible side effects of ICS use. Talk to your doctor about what to expect or if you experience any changes that worry you.

Things to know about inhaled corticosteroids and asthma

If you take an ICS medication for your asthma, your doctor will likely monitor your blood sugar and bone density and advise that you regularly see an eye doctor.4

Growth is monitored in children who take ICS.4

Some ICS drugs contain milk proteins. If you have a milk protein allergy, tell your doctor to choose a medicine that does not contain milk proteins.4

Before taking any inhaled corticosteroids, tell your doctor if you are pregnant or planning to become pregnant.

Tell your doctor about all the medical conditions you have before taking any ICS. Also tell your doctor about any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.1,2

If you have questions about ICS medicines, ask your doctor.

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