In short: Allergies and asthma are closely connected. In allergic asthma, the same triggers that cause hay fever or other allergies, such as pollen, house dust mite, pets and mould, can inflame the airways and cause wheeze, cough and breathlessness. Treating allergic rhinitis well, taking asthma preventer treatment as prescribed and having an up-to-date asthma action plan all help keep both conditions under control.

This guide, written by a Ready Health prescribing pharmacist, explains how allergies and asthma affect each other and what you can do to stay well.

How are asthma and allergies linked?

The nose and the lungs are part of one connected airway, so inflammation in one often goes hand in hand with inflammation in the other. Many people with asthma also have allergic rhinitis, and poorly controlled rhinitis can make asthma harder to manage. When asthma symptoms are triggered mainly by allergens, it is often described as allergic asthma.

When someone with allergic asthma breathes in an allergen, their immune system releases chemicals that make the lining of the airways swell, produce more mucus and tighten. That narrows the airways and causes symptoms.

What allergens commonly trigger asthma?

Pollen: tree, grass and weed pollen in spring and summer.
House dust mite: a year-round trigger, often worse at night.
Animals: cats, dogs, horses and other furred animals.
Mould spores: indoors in damp homes and outdoors in late summer and autumn.

Non-allergic triggers such as colds, cold air, exercise, smoke and air pollution matter too, and many people have a mix of both.

What is thunderstorm asthma?

During some summer thunderstorms, wind can sweep pollen and mould spores up and break them into tiny fragments that reach deep into the lungs. This can cause sudden asthma symptoms, even in people whose asthma is usually mild. It is uncommon, but people with both asthma and hay fever are more at risk. On stormy, high-pollen days, stay indoors with windows closed if you can, keep taking your hay fever treatment and preventer inhaler, and carry your reliever.

How can I manage asthma and allergies together?

Take your asthma treatment as prescribed. Current UK guidance from BTS, NICE and SIGN places inhaled steroid treatment at the centre of asthma care, and many adults now use a combined inhaler as both preventer and reliever. Do not stop or change treatment without speaking to your clinician.
Treat your nose as well as your chest. A daily steroid nasal spray and non-drowsy antihistamine can improve hay fever and may help overall asthma control.
Know your triggers. Allergy testing, interpreted alongside your history, can confirm which allergens matter for you.
Have a written asthma action plan that says what to do when symptoms worsen.
Check your inhaler technique at every review, and attend an asthma review at least once a year.
Prepare for pollen season by starting hay fever treatment early and checking the pollen forecast.

People with severe allergic asthma that remains uncontrolled despite optimised treatment may be referred to a specialist asthma service, where additional treatments can be considered.

Are food allergies linked to asthma?

Yes. People with a food allergy who also have asthma, particularly if it is poorly controlled, have a higher risk of a severe allergic reaction. If you have both, keep your asthma well controlled, make sure you have an allergy management plan, and carry any adrenaline auto-injectors you have been prescribed.

When should I get urgent help?

Call 999 if you are too breathless to speak, eat or sleep, your lips or fingers look blue or grey, your reliever is not helping, or you have swelling of the lips, tongue or throat. Follow your asthma action plan while waiting for help.

Frequently asked questions

Can hay fever turn into asthma?

Hay fever does not directly turn into asthma, but people with allergic rhinitis are more likely to develop asthma, and the two often occur together.

Should I take my preventer inhaler during pollen season even if I feel well?

Yes. Preventer treatment works by controlling airway inflammation over time, so take it as prescribed throughout the year unless your clinician tells you otherwise.

Will allergy testing help my asthma?

It can, by identifying the allergens most likely to trigger your symptoms so you can plan treatment and avoidance more precisely.

Are antihistamines safe if I have asthma?

Non-drowsy antihistamines are widely used by people with asthma. Check with a pharmacist if you take other medicines.

Key takeaways

Allergic triggers such as pollen, dust mite, pets and mould commonly worsen asthma.
Treating hay fever properly supports better asthma control.
Thunderstorms in pollen season can trigger sudden symptoms in people with asthma and hay fever.
Use preventer treatment as prescribed, keep an action plan and have a yearly review.

You might also like our guide to private asthma reviews and treatment plans and our article on hay fever symptoms and prevention.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician.

If you would like to understand your triggers, Ready Health in Standish, Wigan, offers allergy consultations and testing, and you can also book a private GP appointment to discuss your asthma.