Hay Fever and Asthma
One continuous airway, one inflammation. Why pollen season shows up in asthma admissions, what a thunderstorm does, and why the nasal spray is part of asthma treatment.
Part of the Complete Hay Fever Guide.
Key fact: Untreated hay fever makes asthma harder to control, and treating the nose properly measurably improves the chest. The nose and the lungs are one airway with one continuous lining — which is why pollen season shows up in asthma admissions every June.
One airway, not two
The lining of the nose and the lining of the bronchi are continuous, structurally similar and populated by the same inflammatory cells. Allergic inflammation does not respect the boundary between them. This is why the two conditions travel together: the large majority of people with asthma also have allergic rhinitis, rhinitis frequently appears first and predicts who will go on to develop asthma, and the severity of one tends to track the severity of the other.
Treating them as two unrelated problems — a tablet for the nose from one shelf, an inhaler for the chest from a different clinic — is the mistake this guide exists to correct. If your hay fever is uncontrolled, your asthma is being made harder to control, and no amount of reliever inhaler addresses that.
What pollen season does to asthma
The effect is measurable and predictable. Across the UK, asthma exacerbations, unscheduled appointments and hospital admissions all rise through the grass pollen season, and the rise tracks the pollen count. At an individual level, the pattern people describe is a summer in which the reliever inhaler is needed more often, exercise is harder, and sleep is broken by coughing — usually attributed to the heat rather than to the pollen.
~80%
Of people with asthma also have allergic rhinitis
Jun–Jul
When UK asthma attacks driven by grass pollen peak
2 wks
Head start a nasal spray needs to be working by the peak
The mouth-breathing problem
There is a mechanical reason a blocked nose matters to the chest, quite apart from the shared inflammation. The nose warms, humidifies and filters inhaled air. When it is blocked and breathing shifts to the mouth, air arrives at the lower airway colder, drier and carrying more of what was in it. Cold, dry air is itself a bronchoconstrictor in asthma, which is why exercise on a cold day is a classic trigger.
So a blocked nose in June delivers unfiltered pollen-laden air straight to an airway that is already inflamed, all night, every night. Unblocking the nose is not a comfort measure in that situation. It changes what the lungs are breathing.
Thunderstorm asthma
Intact grass pollen grains are too large to reach the small airways; they are filtered out higher up, which is why grass pollen usually causes nose and eye symptoms rather than chest ones. A thunderstorm changes that. The humid downdraught ahead of a storm draws pollen grains down to ground level and ruptures them osmotically into far smaller fragments, which are small enough to be inhaled deep into the lung in very large numbers.
If you have both hay fever and asthma, take a thunderstorm in pollen season seriously. Episodes of mass presentation to emergency departments within hours of a summer storm are well documented, including in people whose asthma is normally mild and in some who did not know they had asthma. Keep your reliever inhaler with you, stay indoors with the windows shut while the storm passes, and do not wait to see whether it settles.
Why treating the nose helps the chest
This is the part that changes what people do. Treating allergic rhinitis properly — specifically, with a regularly used steroid nasal spray rather than an antihistamine alone — is associated with better asthma symptom control, less reliever use and a lower risk of asthma exacerbations and emergency attendances.
The reasons are the ones already described: less shared inflammation, and nasal breathing restored so that air reaching the chest is warmed, humidified and filtered. The practical implication is simple. If you have asthma and hay fever, a steroid nasal spray is not an optional extra for comfort. It is part of your asthma management.
| Treatment | Effect on the nose | Effect on asthma |
|---|---|---|
| Steroid nasal spray — fluticasone furoate, fluticasone propionate, beclometasone, budesonide | The most effective treatment for blockage and the underlying inflammation | Associated with better symptom control and fewer exacerbations |
| Daily non-drowsy antihistamine | Sneezing, itching, runny nose, itchy eyes | Helpful for the nasal symptoms; not a treatment for asthma in itself |
| Preventer inhaler | None | The foundation of asthma control — and the thing most often quietly dropped over summer |
| Reliever inhaler | None | Rescue only. Needing it more often is information, not a solution |
What to do through the season
- Keep the preventer going. Summer is exactly the wrong time to let a preventer inhaler slide, and it is the time people most often do, because the winter viruses have stopped.
- Start a steroid nasal spray two weeks before your season — early May for grass pollen. The UK pollen calendar sets out when each season runs.
- Add a daily antihistamine for the sneezing, itching and eye symptoms.
- Carry the reliever, particularly on high-count days and in unsettled weather.
- Check inhaler technique at the start of the season rather than in the middle of a bad week.
- Have a written asthma action plan and know what it says to do when symptoms step up.
- Treat rising reliever use as a warning. Needing it three or more times a week means the asthma is not controlled, whatever the reason.
When to get help urgently
Call 999 if the reliever inhaler is not helping or not lasting four hours, if you are too breathless to speak in full sentences, eat or sleep, if breathing is fast and it feels like you cannot get enough air, or if lips or fingers look blue. Do not drive yourself.
Arrange a review, without waiting for the season to end, if you are using your reliever three or more times a week, waking at night with cough or wheeze, finding your usual activity limited, or have needed a course of steroid tablets for asthma in the past year.
Frequently Asked Questions
Can hay fever make asthma worse?
Yes, and the effect is well established. Asthma exacerbations and hospital admissions rise across the grass pollen season, and people with both conditions typically need their reliever inhaler more often through the summer. The nose and the lower airway share one continuous lining and the same allergic inflammation, so uncontrolled rhinitis makes asthma harder to control.
Does treating hay fever improve asthma?
Treating allergic rhinitis with a regularly used steroid nasal spray is associated with better asthma symptom control, less reliever use and fewer exacerbations. Two things appear to be at work: less shared inflammation across the airway, and restored nasal breathing, so air reaching the chest is warmed, humidified and filtered rather than arriving cold, dry and unfiltered through the mouth.
What is thunderstorm asthma?
A sudden surge of asthma attacks during or shortly after a summer thunderstorm. Humid downdraughts pull pollen to ground level and burst the grains into fragments small enough to be inhaled deep into the lungs, where whole grains would normally be filtered out by the nose. It can affect people whose asthma is usually mild. If you have hay fever and asthma, keep your reliever with you and stay indoors with windows shut while a storm passes.
Should I keep using my preventer inhaler in summer?
Yes. Summer is when preventer inhalers are most often quietly dropped, because the winter viral triggers have gone, and it coincides exactly with the pollen peak. If anything, pollen season is a reason to be more consistent with a preventer, not less. Any change to preventer treatment should be a decision made with a clinician, not a drift.
I only wheeze in summer. Is that asthma?
It may well be. Seasonal wheeze, cough or chest tightness alongside hay fever is a recognised pattern and it deserves proper assessment rather than being managed with hay fever medicines alone. Antihistamines and nasal sprays do not treat the lower airway. Speak to a clinician about whether you need testing and an inhaler.
References
- NHS. Hay fever. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Allergic rhinitis. cks.nice.org.uk
- British Society for Allergy & Clinical Immunology. BSACI guideline for the diagnosis and management of allergic and non-allergic rhinitis. bsaci.org
- Joint Formulary Committee. British National Formulary: antihistamines, allergen immunotherapy and allergic emergencies. bnf.nice.org.uk
- electronic Medicines Compendium. Summaries of Product Characteristics. medicines.org.uk
- Met Office. Pollen forecast and the UK pollen calendar. metoffice.gov.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Allergy medicines differ in how much drowsiness they cause and in who can take them, and decongestant nasal sprays are not for long-term use. If you have asthma, breathing symptoms that worsen alongside hay fever need review rather than more antihistamine. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.