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# Mast cell stabilisers

Cromoglicic acid and nedocromil: preventers that stop mast cells from releasing histamine and other mediators. They never relieve an attack.

Updated Nov 1, 2026

## What they are

Mast cell stabilisers are very safe preventive drugs applied where the allergy happens: inhaled for asthma and exercise-induced bronchospasm, as a nasal spray for allergic rhinitis, as eye drops for allergic conjunctivitis and orally for systemic mastocytosis. They work only if used regularly or just before exposure, and they have been largely replaced in asthma by inhaled corticosteroids, which are more effective.

## Mechanism of action

They prevent degranulation of sensitised mast cells after allergen exposure, so less histamine, leukotrienes and other mediators are released. The exact molecular action is not fully known; they appear to block calcium entry into the mast cell indirectly. They have no bronchodilator or antihistamine action, which is why they do not help once symptoms have started.

Target: Mast cell mediator release (exact molecular target not established)

## Key points

- Preventer only: no bronchodilator or antihistamine action, useless in an acute attack.
- Given before exercise, cold air or allergen exposure to prevent bronchospasm.
- Very few side effects: local irritation, cough, unpleasant taste.
- Benefit builds over weeks of regular use.

## Drugs in this class

- [**Cromoglicic acid** A mast cell stabiliser that prevents asthma, allergic rhinitis and allergic eye symptoms; it is very safe but does not… Mast cell mediator release](https://durgical.com/en/pharmacology/cromoglicic-acid/)

## Others in the class

- Nedocromil
- Lodoxamide (eye drops)
- Ketotifen (also an H1 antihistamine)

## Test yourself

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

## Can cromoglicic acid stop an asthma attack that has already started?

No; it only prevents mediator release and has no bronchodilator effect.

## When is a mast cell stabiliser best given to prevent exercise-induced bronchospasm?

Shortly before the exercise or other trigger.

## In which three routes is cromoglicic acid used?

Inhaled (asthma), nasal (allergic rhinitis), eye drops (allergic conjunctivitis); also oral for mastocytosis.

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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 - CROMOLYN SODIUM INHALATION SOLUTION solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0209cd6c-5c43-0b93-e063-6294a90ac964) (DailyMed (U.S. National Library of Medicine), 2025); [Cromolyn Oral Inhalation: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a601042.html) (MedlinePlus (U.S. National Library of Medicine), 2016).

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Representative model, for educational purposes only.

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