Allergy
Mast-cell stabilisers
Cromoglicate and related preventers — Preventive treatments that calm allergic reactions in the eyes, nose, lungs and gut — used regularly, not for quick relief.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
Quick answer
What is Mast-cell stabilisers?
Mast-cell stabilisers are preventive anti-allergy medicines used in the eyes, nose, lungs and occasionally the gut. They reduce allergic symptoms when used regularly over time, rather than giving fast relief during a flare.
- How it works: They stabilise mast cells — the immune cells that, in allergy, burst open and release histamine and other chemicals that cause itching, swelling, watering and wheeze.
- In practice: In practice mast-cell stabilisers such as sodium cromoglicate are preventers used regularly to damp down allergic inflammation in allergic eye disease, allergic rhinitis, some asthma, and a few specialist gut and mast-cell conditions.
What it is
Mast-cell stabilisers are preventive anti-allergy medicines used in the eyes, nose, lungs and occasionally the gut. They reduce allergic symptoms when used regularly over time, rather than giving fast relief during a flare.
How it works
They stabilise mast cells — the immune cells that, in allergy, burst open and release histamine and other chemicals that cause itching, swelling, watering and wheeze. By keeping these cells from releasing their contents, the medicines prevent the allergic reaction building up, which is why they must be used before and throughout exposure rather than after symptoms appear.
In practice
In practice mast-cell stabilisers such as sodium cromoglicate are preventers used regularly to damp down allergic inflammation in allergic eye disease, allergic rhinitis, some asthma, and a few specialist gut and mast-cell conditions. The defining practical point is that they work by prevention, not rescue: they have to be used consistently, often several times a day and started before or kept up through the allergy season, and they do not relieve symptoms quickly once a reaction has started — so people who expect instant relief abandon them too soon. They are very safe and well tolerated, with mainly local effects such as brief stinging of eye drops or nasal irritation, which makes them attractive in children and pregnancy and where avoiding steroids matters. For most allergic rhinitis and eye allergy, antihistamines and steroid sprays are more effective first-line, so cromoglicate tends to be an add-on or alternative. An oral form is used for a specific gut condition (mastocytosis/food-related mast-cell symptoms) and acts locally in the bowel rather than being absorbed.
Examples
Practical use
How to take it & use it well
- Use these treatments regularly every day as a preventer, even when you feel fine, as they work by stopping symptoms building up rather than relieving them once they start.
- Understand that they will not give you quick relief during an attack, so keep any separate reliever or rescue treatment you have been given for sudden symptoms.
- For eye drops or a nasal spray, start using them before and throughout the season you usually react, as they need time and steady use to take full effect.
- Follow the technique you have been shown, such as shaking an inhaler or aiming a nasal spray slightly away from the centre of the nose, for the best results.
- Keep going for the whole period advised rather than stopping as soon as you feel better, since the benefit is lost quickly once you stop using them.
- A little local stinging, a bitter taste or mild irritation can happen at first and usually settles, but mention anything that troubles you to your pharmacist.
Common uses
- Allergic conjunctivitis (eye drops)
- Allergic rhinitis (nasal spray) and some asthma
- Specialist gut/mast-cell conditions (oral)
Monitoring
- Symptom control with regular use
- Whether a more effective first-line option is needed
- Local tolerance (eye/nose)
Weighing it up
Advantages & disadvantages
Advantages
- They prevent allergic and some asthma symptoms from developing when used regularly over time.
- They are very safe and gentle, with few side effects, which makes them suitable for many people, including children.
- Because little is absorbed into the body, they avoid many of the effects of medicines taken by mouth.
- They come in several forms, including eye drops, nasal sprays and inhalers, to target where you react.
- They can reduce the need for stronger treatments when used steadily as part of a prevention plan.
Disadvantages
- They are preventers, not relievers, so they do nothing for symptoms that have already started.
- They have to be used regularly and consistently to work, which is easy to forget when you feel well.
- The benefit builds up slowly, so they are not helpful for quick or one-off relief.
- They can cause mild local stinging, a bitter taste or short-lived irritation where applied.
- Their effect wears off soon after stopping, so protection is lost if use is not kept up.
Key safety principles
What to watch for
- Preventive, not a reliever — use it regularly and start before/through the allergy season; it will not relieve a reaction quickly.
- Very safe with mainly local effects (brief eye stinging or nasal irritation); attractive in children and where steroids are best avoided.
- Often an add-on or alternative — antihistamines and steroid sprays are usually more effective first-line for nose and eye allergy.
Key interactions
What to avoid or check alongside
- They have very few interactions with other medicines because so little is absorbed into the body.
- If you use other eye drops, leave a short gap between them so each has time to work.
- When used alongside other allergy or asthma treatments, they are meant to add to, not replace, your reliever.
- Tell your pharmacist about your other treatments so your overall prevention plan stays balanced.
- Contact lens wearers should check whether to remove lenses around eye drops, as some preservatives can affect them.
Patient & carer advice
- Use it regularly every day for it to work — it prevents symptoms rather than relieving them on the spot
- Start before the season or exposure where you can, and keep going through it
- Brief stinging of the eye drops or nose spray is normal and settles
Answers
Mast-cell stabilisers: frequently asked questions
Why isn't my mast cell stabiliser helping during an attack?
These medicines are preventers, not relievers, so they will not ease symptoms that have already started. They work by stopping reactions building up when used every day in advance. Keep any separate rescue or reliever treatment for sudden symptoms, and use the stabiliser regularly for prevention.
Do I need to use it even when I feel fine?
Yes. The whole point of these treatments is to prevent symptoms, which only works if you use them consistently, including on good days. Stopping when you feel well lets the protection fade, so keep going for the full period you have been advised.
Are mast cell stabilisers safe for children?
They are among the gentler allergy treatments, with few side effects and little absorbed into the body, which is why they are often suitable for children. Always follow the specific instructions for the form and the child's age, and ask your pharmacist if unsure.
When should I start using them for hayfever?
Start before the season you usually react and keep using them throughout, because they take time and steady use to build up their effect. Beginning only once symptoms are in full swing means they work far less well.
Is the stinging in my eyes or nose normal?
A little local stinging, irritation or a bitter taste when you first use them is common and usually settles with continued use. If it is severe, persistent or you develop swelling, stop and check with your pharmacist or GP.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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