Pharmacology · Inhaled corticosteroids
Budesonide !
An inhaled corticosteroid that controls asthma by calming airway inflammation. Used daily as a preventer, by inhaler or nebuliser in young children.
Updated 2026-11-01
No structure of budesonide on the glucocorticoid receptor exists. The figure shows fluticasone furoate, another inhaled corticosteroid that occupies the same steroid pocket, in the human glucocorticoid receptor ligand-binding domain.
Mechanism of action
Budesonide binds the glucocorticoid receptor in airway cells. The receptor moves to the nucleus, switches off genes for cytokines, chemokines and adhesion molecules and switches on anti-inflammatory genes. Airway eosinophils, mast cells and T cells fall, the airways become less reactive and asthma attacks become less frequent. Most of the swallowed fraction is destroyed on first pass through the liver, which limits systemic effects.
- Budesonide enters airway cells and binds the glucocorticoid receptor
- The receptor moves to the nucleus and changes gene transcription
- Inflammatory cytokines and airway eosinophils decrease
- Airway reactivity falls and asthma attacks become rarer
Pharmacokinetics
- Absorption
- Acts locally; the swallowed part is mostly removed by the liver on first pass
- Metabolism
- In the liver by CYP3A4 to metabolites with low activity
- Elimination
- As metabolites in urine and faeces
- Onset and duration
- Benefit builds up over days to weeks of regular use
Indications
- Maintenance and preventive treatment of asthma, including young children by nebuliser Asthma →
- In COPD, combined with a long-acting bronchodilator in patients with frequent exacerbations Chronic obstructive pulmonary disease (COPD) →
Adverse effects
Common
- Oral thrush (candidiasis)
- Hoarseness and sore throat
- Cough
- Respiratory infections, ear infections and nosebleed in children
Contraindications
- Primary treatment of status asthmaticus or other acute attacks needing intensive measures
- Hypersensitivity to budesonide or any component
Key interactions
- Strong CYP3A4 inhibitors (ritonavir, ketoconazole, itraconazole, clarithromycin)
- Higher budesonide levels and systemic steroid effects (Cushing syndrome, adrenal suppression)
What is monitored
- Asthma control and reliever use
- Mouth and throat for thrush
- Height in children
- Eyes and bone density with long-term high doses
Administration and safety
- Oral inhalation by dry powder inhaler or pressurised inhaler; a spacer with a pressurised inhaler improves delivery to the lungs and reduces deposits in the mouth
- The nebuliser suspension is used only in a jet nebuliser (not ultrasonic) and is not mixed with other nebuliser medicines
- After each use the mouth is rinsed with water and the water spat out; with a face mask, the face is washed afterwards
- It is a preventer, used every day even when well; it does not relieve an attack
Nursing care
- Check inhaler or nebuliser technique, and that the mask fits and keeps the mist away from the eyes
- Look at the mouth for white patches and ask about hoarseness
- Measure and plot growth in children
- Teach that the benefit takes days to weeks and that stopping suddenly can let asthma flare
Pregnancy and breastfeeding
Published studies in pregnant women have not shown a clear risk with inhaled budesonide; poorly controlled asthma raises the risk of preeclampsia and prematurity.
Test yourself
Think of the answer, then tap the question to see it.
Why is systemic exposure to inhaled budesonide low?
It acts locally in the lung and most of the swallowed part is broken down by the liver on first pass.
Can budesonide alone treat status asthmaticus?
No. It is a preventer; acute severe attacks need bronchodilators and systemic corticosteroids.
Which kind of nebuliser must not be used for budesonide suspension?
An ultrasonic nebuliser; a jet nebuliser is used.
Related drugs
Related conditions
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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 - BUDESONIDE INHALATION SUSPENSION- budesonide inhalant (DailyMed (U.S. National Library of Medicine), 2024); Budesonide inhalers: medicine to treat asthma - NHS (NHS, 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.