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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Inhaled corticosteroids

Steroids breathed into the lungs to calm airway inflammation. The most effective controller medicines for asthma; they do not relieve an attack.

Updated 2026-11-01

## What they are

Glucocorticoids delivered by inhaler or nebuliser (budesonide, beclometasone, fluticasone, ciclesonide, mometasone). They are the basis of long-term asthma control and, in COPD, are added for patients with frequent exacerbations. They are often combined with a long-acting beta-2 agonist in one inhaler.

## Mechanism of action

The steroid crosses the cell membrane and binds the cytoplasmic glucocorticoid receptor, which moves to the nucleus. There it switches off inflammatory genes (cytokines, chemokines, adhesion molecules) by blocking transcription factors such as NF-kB and AP-1, and switches on anti-inflammatory genes. Eosinophils, mast cells and T cells in the airway fall and airway hyperresponsiveness decreases. Delivery to the lung and extensive first-pass liver metabolism of the swallowed part keep systemic effects low.

Target: Glucocorticoid receptor (NR3C1), a nuclear receptor

## Key points

- Controllers, not relievers: they are not used for acute bronchospasm or as primary treatment of status asthmaticus.
- Oral thrush and hoarseness (dysphonia) are the classic local effects; rinsing the mouth and spitting, and a spacer, reduce them.
- High doses for long periods: adrenal suppression, lower bone density, cataracts and glaucoma, slower growth in children.
- In COPD they raise the risk of pneumonia.
- Strong CYP3A4 inhibitors (ritonavir, ketoconazole) can cause Cushing syndrome and adrenal suppression, especially with fluticasone.

## Drugs in this class

- [**Budesonide** An inhaled corticosteroid that controls asthma by calming airway inflammation. Used daily as a preventer, by inhaler… Glucocorticoid receptor](https://durgical.com/en/pharmacology/budesonide/)
- [**Budesonide + formoterol** One inhaler with a corticosteroid and a fast, long-acting beta-2 agonist. Controls asthma and COPD; in some schemes it… Glucocorticoid receptor (budesonide) and beta-2 adrenergic receptor (formoterol)](https://durgical.com/en/pharmacology/budesonide-formoterol/)
- [**Beclometasone** One of the oldest inhaled corticosteroids, a daily asthma preventer. It is a prodrug activated in the lung. Glucocorticoid receptor](https://durgical.com/en/pharmacology/beclometasone/)
- [**Fluticasone** A potent inhaled corticosteroid for asthma and, in combinations, COPD. Almost none of the swallowed drug reaches the… Glucocorticoid receptor](https://durgical.com/en/pharmacology/fluticasone/)

## Others in the class

- Ciclesonide
- Mometasone

## Test yourself

Think of the answer, then tap the question to see it.

## How do inhaled corticosteroids reduce airway inflammation at the gene level?

The activated glucocorticoid receptor blocks transcription factors such as NF-kB and AP-1, switching off inflammatory genes, and switches on anti-inflammatory ones.

## What two measures reduce oral thrush from an inhaled corticosteroid?

Rinsing the mouth with water and spitting it out after each use, and using a spacer with a pressurised inhaler.

## Which antiretroviral booster causes Cushing syndrome with inhaled fluticasone?

Ritonavir, a strong CYP3A4 inhibitor that greatly raises systemic fluticasone levels.

## Which respiratory infection is more frequent with inhaled corticosteroids in COPD?

Pneumonia.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - FLUTICASONE PROPIONATE HFA- fluticasone propionate aerosol, metered](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=99249b31-bf0a-464f-8335-845279350dbe) (DailyMed (U.S. National Library of Medicine), 2023); [DailyMed - BUDESONIDE AND FORMOTEROL FUMARATE DIHYDRATE aerosol, metered](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd352302-e2fe-4388-b4b0-00b34f6ebe48) (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 44 (McGraw Hill, 2023).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/inhaled-corticosteroids/