Understanding hay fever: A comprehensive guide

Hay fever is the common name for symptoms like sneezing and a stuffy nose caused by an allergy to pollen. Doctors refer to it as allergic rhinitis and it happens when you breathe in the tiny airborne plant particles, triggering inflammation in the tissue lining your nose. ¹

Hay fever is quite a modern problem. The condition was first described more than 200 years ago and gradually became more common as industry developed. In the 1950s the number of people with allergic rhinitis really began to grow and it’s still growing all around the world. Hay fever can make you feel miserable as well as unwell and interfere with daily life. Yet many people never even see their GP about it and instead manage their pollen allergy themselves. So they may struggle without knowing there could be other options.¹

That’s what our guide is for, to explain those options. Find out what hay fever is, what causes it and how to spot the symptoms. Then move on to getting a diagnosis and how that can lead to the right hay fever treatment for you to relieve symptoms. This is important and not just for right now but because hay fever can lead to other health conditions too.¹

What exactly is hay fever?

The difference between hay fever vs allergies to other airborne substances is the name. Otherwise it’s like an allergic reaction to breathing in pet dander, dust mites or mould. Plants release pollen at different times of year as part of their reproductive cycle and some can trigger hay fever symptoms.¹ 

But how long does hay fever last? It could be for weeks at a time or even months depending on the type of pollen and whether you react to more than one plant. This is a common type of allergic rhinitis.¹

What causes hay fever?

Your immune system causes hay fever by overreacting to harmless pollen in the air you breathe, mistakenly identifying the tiny particles as dangerous. It tries to protect you by producing antibodies called Immunoglobulin E (IgE) and releasing chemicals like histamine to fight off your allergy trigger whenever they detect it.³

Histamine is behind your runny nose and other annoying hay fever symptoms.³ You’re not contagious as you would be with a cold. And the symptoms usually die down when it’s not your allergy season. The timing depends on what type of pollen you’re allergic to, where you live and the weather.¹ Hay fever is closely linked to the environment.

Meanwhile, chronic hay fever symptoms all year round could be a reaction to a different airborne allergen, probably one that’s indoors like dust mites or animal dander.¹

Which types of pollen trigger hay fever?

About 95% of Britons with hay fever react to grass pollen;⁴ in 2023, visits to the hay fever page on the NHS website tripled between early May and mid-June.⁵ Pollen from trees and weeds are triggers but not usually colourful flowers pollinated by insects, like pear or cherry blossom.^1,6

These are some of the common culprits:⁷

• Tree pollen: alder, ash, beech, birch, cedar, elm, fir, hazel, hornbeam, horse chestnut, lime, maple, oak, pine, plane, poplar
• Grass pollen: meadow timothy, common clump grass, meadow bluegrass, common smooth oats, meadow foxtail, perennial ryegrass, soft brome, common rye grass, tall fescue, flying oats and woolly honey grass
• Weed pollen: mugwort, nettle, plantain, ragweed

Does hay fever vary by season or region?

Hay fever generally strikes in spring, summer and autumn.¹ Trees release pollen first, once temperatures hit 13C and often before their leaves are out to get in the way.^8,9 Then it’s grass, followed by weeds.¹ Shorter days in late summer signal mugwort pollen to start flying.¹⁰ 

Plants are part of our environment so of course changing conditions could have a big influence on your typical pollen season. 

Exactly how does the environment influence hay fever?

Climate change does seem to be causing heavier pollen production, more allergenic pollen and longer pollen seasons. For instance, a milder winter can trigger trees and grass to start releasing pollen early.¹ Daily changing aspects of your local environment, like rainfall, can influence your hay fever too.¹¹

Warm dry spells generally encourage pollen production and if it’s windy too the fine powdery grains can travel further. Steady light rain and humidity can weigh the tiny particles down, which is helpful. But a sudden downpour can be unhelpful, scattering and splashing the particles around.¹¹

What are the symptoms of hay fever?

Typical hay fever symptoms to look out for include:¹ 

• Nasal stuffiness ¹
• Runny nose ¹
• Sneezing ¹
• Itchy nose and throat ^1,6
• Postnasal drip (the build-up of mucus at the back of your throat) ¹
• Red, watery or itchy eyes ¹

You might also experience:¹

• A cough
• Chest tightness or wheezing

You can see how hay fever symptoms might make life quite a struggle.¹ 

Stuffy nose¹²

You breathe in pollen, which sets off an allergic reaction causing blood vessels and tissue in your nose to become inflamed. Your nose may feel so blocked you can only breathe through your mouth. It’s been found that one possible effect of nasal congestion is being less productive at work.¹

Runny nose¹³

A runny nose, like a stuffy nose, is a common early sign of a bout of hay fever. This first phase of the allergic reaction, when you’ll probably be sneezing too, usually lasts for about 2 or 3 hours after you have contact with your pollen trigger.

Sneezing¹⁴

Sneezing is a way for your body to get rid of anything that’s irritating your nose including tiny particles of pollen. The inflammation caused by the allergic reaction stimulates a nerve, which then sends a message to the sneezing centre in your brain, triggering the achoo. 

Postnasal drip^{1, 12}

Postnasal drip is when mucus drains down the back of your throat, usually without you noticing. But hay fever can give you a runny nose and inflamed sinuses, turning that drip into a persistent flow, which can be irritating, especially at night when you’re lying down and the mucus pools. 

Allergy cough^{1, 15, 16, 17}

Coughing can be the result of irritation in your throat from hay fever postnasal drip. You breathe in pollen and almost immediately your immune system reacts to expel the (harmless) threat from your airways, triggering the cough reflex. 

A cough can also be a symptom of allergic asthma. This is when pollen causes a reaction in your lower airways.

Chest tightness and wheezing¹⁶

Some people with hay fever also get tight chest and wheezing after contact with pollen. These are among the common symptoms of allergic asthma. The allergic reaction makes your airways swell and produce more mucus, which starts to clog your bronchial tubes.

Itchy, red, watery eyes¹

Hay fever and allergic pink eye are so commonly seen together that there’s a name for the combined group of symptoms: allergic rhinoconjunctivitis. Pollen lands on your eye and triggers allergic inflammation on the surface and inside the lids, typically making you produce more tears than usual and causing itching.

How does hay fever affect daily life?¹

Hay fever can make you feel miserable and miss days at work or school. It may be hard to get a good night’s sleep, which can interfere with concentration and performance. Your social life might suffer and you may have to give up certain activities at least during pollen season. 

How is hay fever diagnosed?

Diagnosing hay fever usually involves the doctor asking about your allergy symptoms, your medical history and whether there’s allergic rhinitis in the family, which could make you prone to it too. You’ll probably have a physical examination and one or more allergy tests.¹

Try keeping an allergy diary to take to each clinic appointment. Note when exactly you get hay fever symptoms, how long they last, whether you take medication for them and what you think the trigger might be. If the allergy symptoms tend to happen indoors and calm down in winter, you may be allergic to dust mites, pet dander or mould instead. Your GP will also be able to rule out other conditions like a bad cold.¹

What tests are used for diagnosing hay fever?

There are two common types of allergy tests that can help your doctor make a diagnosis. Both can check several allergens at once: ¹

• Skin prick test: Clinic staff put drops containing the suspect pollen onto your forearm (or upper back for young children) and watch for signs of an allergic reaction.
• Blood test: A small sample goes to the lab, which will check if your immune system has made antibodies to a particular pollen.

When should you see a doctor for hay fever?

See your GP to discover what’s making you feel unwell or if you already have a diagnosis and your hay fever symptoms aren’t under control. Over-the-counter allergy medication works for some people but you may need a different approach and the doctor can review your treatment plan.¹

Hay fever vs cold

Symptoms of hay fever and the common cold, which is caused by a virus, are similar but the timing is usually quite different and can help you tell the difference: ^1,18

Cold symptoms: 

• Build over a couple of days
• Last less than two weeks

Hay fever symptoms:

• Can appear suddenly
• May last several weeks or months each year

Are certain people more prone to hay fever?¹

You’re more likely to develop hay fever if other members of your family have allergies because this can be an inherited condition. Environmental factors can increase the risk too, for instance living somewhere with high air pollution or being exposed to allergens at work, say in farming. 

How does genetics play a role in hay fever?¹⁹

Having a faulty filaggrin gene can make your skin less effective as a natural barrier against the outside world. Allergens can pass through more easily and put your immune system on alert, which seems to increase the risk of developing allergic conditions like eczema, hay fever and asthma. 

What are the treatment options for hay fever?

Hay fever treatment options include avoiding your pollen trigger and using short-term allergy relief, over-the-counter or prescription, as needed.¹ That may mean daily medication during hay fever season. A third option is allergy immunotherapy where the aim is fewer symptoms and less need for regular relief even after treatment ends.³

People often ask how to stop hay fever immediately but medication doesn’t just switch symptoms off. Left to run its course, a bout of hay fever could take up to 30 hours or so to subside.¹³ That’s if you haven’t breathed in pollen again in the meantime. Short-term relief could start to have an effect on nasal symptoms after 30 minutes or within a few hours, depending on the type and form.^1,20 

Avoiding allergens: 8 ways to reduce your exposure to pollen

1. Use a pollen calendar to find out when your trigger plant is likely to flower

2. In allergy season check the pollen forecast online or in our app every day to help you plan your activities

3. Avoid going outside at peak pollen times

4. Wear a wide-brimmed hat, wrap-around sunglasses and a face mask if you do need to go out, and maybe take an antihistamine, a type of short-term allergy relief, beforehand²⁰

5. Keep windows and doors closed and air your home when the pollen count is low

6. Think about getting an air purifier

7. Wash your hair before going to bed and leave your clothes outside your bedroom

8. Dry laundry indoors in pollen season

Short-term hay fever relief: Prescription and over-the-counter medications

There are several types of short-term hay fever relief available:¹

• Antihistamines block the effects of histamine, which is what causes a lot of your symptoms, and come as tablets, nasal sprays, creams and eye drops
• Corticosteroids mimic an anti-inflammatory hormone your body makes naturally and come as nasal sprays, inhalers, creams, lotions or tablets
• Decongestants tackle both a stuffy nose and a runny nose and come as tablets or nasal sprays

Using a simple saline nasal spray as well can help your hay fever symptoms a lot and make it easier to breathe.¹² 

Possible side effects of short-term hay fever medications

Allergy medications can cause side effects like any medicine. Read the patient information leaflet carefully and ask your GP for advice. 

First-generation antihistamines like chlorphenamine, promethazine, and diphenhydramine (sold under various brand names) can make you drowsy. That’s why newer types of antihistamine are generally preferred. Corticosteroid nasal sprays may cause local irritation. And decongestants could actually make symptoms worse if you use them for more than a few days at a time.^1,20

Long-term hay fever relief: Allergy immunotherapy

Allergy immunotherapy tackles the underlying cause of allergic rhinitis by retraining the immune system to be more tolerant of pollen.⁴ The goal is you have fewer allergy symptoms so need less short-term relief medicine, and are at less risk of developing new allergies or allergic asthma.⁷  

Treatment could be daily tablets or drops at home or injections at the clinic, once or twice a week initially and then more spaced out.²¹ You may start to feel the benefit within months but it’s important to finish the full course, which is usually 3-5 years.²²

Your doctor will know if you could be eligible for treatment and, if so, which form – tablets, drops or injections. That will depend on your age and trigger.

Possible side effects of long-term hay fever relief

Allergy immunotherapy can cause mild local symptoms, usually at the start and less so after a couple of weeks. Severe allergic reactions are rare but possible, more so with allergy shots.²¹ Whichever type of treatment it is, your doctor will be prepared for every side effect and so will you. 

Can hay fever lead to other health issues?

Hay fever can lead to blocked sinuses, sinusitis and ear infections, and to allergic asthma, if your symptoms are not well-controlled.^1,12,19  Pollen allergy may also give you a mild local reaction when you eat certain fresh fruit, vegetables, nuts or spices, although it doesn’t happen to everyone.¹

What is the link between hay fever and asthma?

Hay fever triggered by pollen or another airborne allergen increases the risk of children developing asthma before they reach puberty by up to 7 times (according to the study, Childhood Allergic Rhinitis Predicts Asthma Incidence and Persistence to Middle Age, 2007).²³ 

Also, around 80% of people with asthma have rhinitis.¹ This interconnection is part of how allergies can progress, known as the allergic march.¹⁹

Why does pollen allergy cause you to react to certain foods?

Proteins in certain plant-based foods are similar to those in some pollen types and that can confuse your overactive immune system into reacting when you eat them. It’s called oral allergy syndrome (OAS) or pollen food syndrome (PFS) and the symptoms are local, like an itchy mouth, lips and throat.¹

You could get hay fever from birch pollen and also react to peach; or have grass pollen allergy and find eating melon affects you.¹ 

Don’t assume it’s a cross-reaction though, especially if it happens when you eat nuts.¹ A primary nut allergy can cause the same local symptoms but also carries the risk of life-threatening anaphylaxis. So seek medical advice and a diagnosis.⁷ 

You can also speak to your GP, about any other allergy symptoms you’re concerned about.

The short version

Hay fever affects more and more people around the world. It’s an allergic reaction to pollen from trees, grass or weeds. Symptoms include nasal stuffiness, postnasal drip and watery eyes. A type of allergic rhinitis, hay fever follows the different pollen seasons and usually stops in winter. ¹

To diagnose hay fever your GP will need to know all about your symptoms and medical history, and whether there’s any family history of allergies. They’re likely to suggest allergy testing too. Treatment usually involves a combination of allergen avoidance, plus short-term hay fever relief and maybe allergy immunotherapy to reduce the symptoms in the longer-term.¹

Hay fever can lead to other health issues such as blocked sinuses, ear infections and allergic asthma so it’s important to tackle it promptly.^1,12,19