Hay fever

Introduction 

Hay fever advice

Hay fever is an allergy to pollen that affects around one in four people. An expert explains how it is diagnosed, symptoms and treatment.

Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines

The ARIA guidelines were developed during a World Health Organization (WHO) workshop in 1999 by a panel of experts. They were updated in 2008.

The ARIA guidelines have changed the terms that were traditionally used to describe allergic rhinitis. Allergic rhinitis is no longer described as ‘seasonal’ when it occurs during the summer months and ‘perennial’ when it occurs all year round.

Instead, allergic rhinitis can either be:

  • intermittent: symptoms are present for up to four days a week, or for up to four weeks in a row, or
  • persistent: symptoms are present for more than four days a week, or for more than four weeks in a row.

These terms have been changed to better reflect the reality of people’s symptoms.

Previously, ‘seasonal’ was used to mean an allergic reaction at a particular time of the year, usually caused by outdoor allergens, such as pollen. ‘Perennial’ meant that the allergic reaction symptoms lasted all year, and were usually caused by indoor allergens, such as dust mites.

In reality, pollens can be present and cause allergic reaction symptoms throughout the year, and those with allergies to ‘all year’ allergens, such as dust mites, may not have their symptoms all year round.

The new terms of ‘intermittent’ and ‘persistent’ define allergic rhinitis based on the frequency of the symptoms, not the time of year they appear or the allergens that cause them. 

Hay fever is a type of allergic rhinitis caused by pollen or spores. Allergic rhinitis is a condition where an allergen (something that causes an allergic reaction) makes the inside of your nose inflamed (swollen).

Hay fever affects the nose, sinuses (small air-filled cavities behind your cheekbones and forehead), throat and eyes. It causes:

  • sneezing,
  • a runny nose, and
  • itchy eyes.

Hay fever usually occurs in spring and summer, when there is more pollen in the air. Trees, grass and plants release pollen as part of their reproductive process. Mould and fungi also release tiny reproductive particles, called spores.

People with hay fever can experience their symptoms at different times of the year, depending on which pollens or spores they are allergic to.

Allergic rhinitis can be classified as either intermittent or persistent, depending on how often people experience their symptoms (see box, left)

Allergic reaction 

The symptoms of hay fever occur when the immune system (the body’s defence system) overreacts to a normally harmless substance, in this case pollen. When the body comes into contact with pollen, cells in the lining of the nose, mouth and eyes release a chemical called histamine. This triggers the symptoms of an allergic reaction.

How common is it?

Hay fever is a common condition that affects around 20% of people in the UK. Hay fever is more likely if there is a family history of allergies, particularly asthma or eczema. In England, there may be over 10 million people with hay fever.

Outlook

Hay fever cannot be cured completely, but there are a number of treatments available to relieve the symptoms. These include antihistamine tablets, nasal (nose) sprays and eye drops. Some can only be prescribed by a GP, but many are available over-the-counter (OTC) in pharmacies. 

For persistent hay fever, a treatment known as immunotherapy can be used to gradually increase a person’s exposure to the allergen while monitoring their response. This can be effective at reducing the severity of an allergic reaction, but is not suitable for everyone.

  • show glossary terms

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance, such as pollen, that reacts with the body's immune system and causes an allergic reaction.

Sneezing
Sneezing is an involuntary expulsion of air and bacteria from the nose and mouth.

Last reviewed: 03/12/2009

Next review due: 03/12/2011

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