Long grass - banner

Pollen

Find out why pollen causes hay fever, how it can affect asthma, and how to manage a pollen allergy.

You may have heard that pollen is a common trigger for people with asthma. Here's all you need to know...

What is pollen?

Pollen is a tiny powder-like substance produced by certain types of trees, grasses and weeds. It is spread by insects and the wind. An allergy to grass or hay pollen is known as hay fever. The term hay fever is now also widely used to include allergies to other pollens (such as trees and weeds).

Who is most likely to have hay fever?

Hay fever is very common. It affects about 1 in 5 people in the UK. Teenagers and young adults are most commonly affected, although it can develop any at age. The condition is more common in boys than in girls. In adults, men and women are equally affected.

Hay fever and asthma are closely linked. Research results vary but its thought that between 20% and 60% of people with hay fever also have asthma. Approximately 80% of people with asthma also have a pollen allergy (which means their asthma symptoms are triggered by pollen).

Symptoms of hay fever

The most common symptoms of hay fever are:

  • blocked nose
  • watery, runny nose
  • sneezing
  • itchy nose
  • watery eyes.

Other symptoms include:

  • headaches
  • reduced sense of smell
  • itchy eyes
  • disrupted sleep and tiredness
  • earache.

Why can pollen increase your risk of asthma symptoms or an asthma attack?

Pollen contains proteins that are harmless for most people. In people with hay fever these proteins cause the immune system to overreact and release a chemical called histamine. This chemical causes the nose, eyes, throat and sinuses (small air-filled cavities behind your cheekbones and forehead) to become swollen, irritated and inflamed.

For many people with asthma, this release of histamine (caused by hay fever) can make asthma symptoms worse.

Having a blocked nose can also affect asthma control. Usually when you breathe in, you breathe in through your nose so the air is warmed and moistened by the nasal passages. When you breathe in through your mouth, the air you're inhaling is colder and drier. In some people with asthma, the airways are sensitive to this and react. This can lead to asthma symptoms, such as coughing, wheezing, a shortness of breath and tightness in the chest.

How do you know if pollen is your trigger?

Keeping a diary can help you notice if pollen is a trigger for your asthma symptoms. If, for example, you get symptoms after you’ve been in the garden or walking in the woods at a certain time of the year, it could suggest a pollen allergy.  

Noting the daily pollen count can also help you spot whether or not your allergy symptoms are worse when the count is high.

Your GP may prescribe some medicines to see if they help your symptoms. Or they may refer you for a skin prick test and/or blood test to confirm whether or not you're allergic to pollen and to identify which pollen(s) you're allergic to.

When is pollen most likely to affect you?

There are hundreds of different types of grasses, trees and weeds in the UK. Different types of pollen are released at different times of the year in different parts of the country (due to variations in climate and plant life). In the UK:

Tree pollens tend to affect people from March to May each year, but can cause symptoms from as early as January. About 20 per cent of people with hay fever are allergic to birch tree pollen. Oak and plane trees (common in many streets in London) also affect lots of people.

Grass pollens are the most common cause of hay fever and usually affect people in May, June and July.

Weed pollens (such as nettles and docks) usually release pollen from early spring to early autumn.

If you know pollen is a trigger for your asthma, speak to your GP or asthma nurse to include hay fever medicine in your action plan.

Met Office - Pollen infographic

Source: metoffice.gov.uk

It is possible to be allergic to more than one type of pollen.

Can the weather affect hay fever symptoms?

On hot, sunny days, more pollen is released so the pollen count tends to be higher. Air pollution can peak during warm, dry days too, and the combination of both can cause 'grey fever'. Less pollen is released on cooler, cloudy days.

If air pollution levels are high, this can make hay fever symptoms worse because it creates a smog which traps pollen, preventing it from escaping into the upper atmosphere.

During a thunderstorm when the humidity is high, high levels of pollen can be swept up high into the air where the moisture breaks them into much smaller pieces. As the pollen settles back down, these smaller pieces can be breathed into the smaller airways of the lungs where they can irritate the airways and trigger asthma symptoms.

Can a bunch of flowers trigger hay fever symptoms?

Some people may find the smell of cut flowers can trigger asthma symptoms.

What's the best way to reduce the risk of pollen affecting you?

It's difficult to avoid pollen completely, but there are a number of ways you can reduce the risk of pollen affecting you.

1. Take the asthma attack risk checker. Most people don't think they're at risk of a potentially fatal asthma attack. Around 75% of emergency hospital admissions could be preventable with better management and support. In just 60 seconds, it will reveal your risk of having an asthma attack and tell you how you can reduce it.

2. Manage your asthma well. This is the best way to reduce the risk of pollen making your asthma symptoms worse. You can do this by:

  • Taking your medication regularly as prescribed.
  • Using a written asthma action plan.
  • Going for regular asthma reviews.

3. Take medicines for hay fever. Research shows that anyone with asthma who also has hay fever can significantly reduce their risk of going to A&E or being hospitalised if they treat their hay fever. This could include nasal steroids, anti-histamines or anti-inflammatory eye-drops; so ask your pharmacist or GP which one is right for you.

4. Try these practical tips that people with asthma have shared with us. This is especially important on dry, warm and sunny days when the pollen count is usually higher.

  • Keep doors and windows closed when you're indoors.
  • Wear wraparound sunglasses to stop pollen getting in your eyes when you're outside.
  • Change your clothes and have a shower when you've been outside.
  • Don't cut the grass and avoid walking in grassy areas.
  • If possible, avoid drying your clothes outside as pollen will stick to them.
  • Remember that pollen counts are generally higher in the early morning and late afternoon/early evening, so it may be better to avoid being outside at these times if possible.
  • Dust with a damp cloth and vacuum with a HEPA (high-efficiency particle arresting) filter regularly.
  • Don't smoke or let other people smoke around you because it can make hay fever (and asthma) symptoms worse.
  • Alcohol can increase your sensitivity to pollen so it may be worth avoiding it when the pollen count is high and/or your symptoms are severe.
  • If possible, don't go outside before, during or just after a thunderstorm.
  • Keep an eye on air pollution levels on the Defra website and, if possible, avoid going out when air pollution levels are particularly high.
  • When you're booking a holiday, remember that the pollen count is likely to be lower in locations by the sea.
  • If you're going abroad, check the local pollen information and forecast before travelling. 
  • We also have useful advice for anyone taking exams during the hay fever season.

Last updated February 2015