How asthma inhalers work – the simple explanation
Why asthma inhalers can open narrowed airways, calm inflammation or do both, and how poor technique can make a good treatment seem ineffective.
Asthma has both tightening and inflammation
Asthma symptoms happen when the airways narrow and become inflamed or sensitive. A reliever medicine can relax airway muscle for quicker symptom relief, while an inhaled corticosteroid controller reduces inflammation over time. Some treatment plans combine roles. The inhaler only works well if the medicine reaches the lungs.
The medicine and the delivery device
A metered-dose inhaler releases a measured spray that needs coordinated breathing. A dry-powder device depends on a strong, correctly timed breath. A spacer can help with an appropriate metered-dose inhaler. Switching devices can change the technique and sometimes the prescribed dose, so re-training is needed.
The formulary shows examples of the roles discussed:
Salbutamol (Inhaler) — Ventolin, Asthavent, Cipla Salbutamol, Aerolin
Asthma (reliever); COPD (reliever); acute bronchospasm
Beclometasone — Beclate, Becotide, Clenil, Aerobec
Asthma — inhaled corticosteroid preventer
Budesonide / Formoterol — Symbicort
Asthma (maintenance and reliever therapy — MART); COPD maintenance
Check whether the medicine is reaching you
- Read the device name and confirm whether it is a reliever or preventer.
- Ask a health professional to observe the full technique.
- Check the mouthpiece, dose counter and spacer for damage or blockage.
- Take the inhaler to appointments so the technique can be checked again.
A failing inhaler technique needs a review
Common questions
- How do asthma inhalers work?
- Some relax narrowed airway muscle, some reduce airway inflammation and some combine those effects. The prescribed device technique determines how much medicine reaches the lungs.
- What is in an asthma inhaler?
- The active medicine depends on the inhaler. Check the label or ask a pharmacist whether it is a reliever, preventer or combination product; do not identify it by colour alone.
Sources
- Primary Healthcare STG and EML, Appendix II: Respiratory devicesNational Department of Health, South Africa
- Primary Healthcare Standard Treatment Guidelines and Essential Medicines ListNational Department of Health, South Africa
Last reviewed 26 August 2026.