Hay fever (or hayfever) also known as allergic rhinitis, is a common condition that shows signs and symptoms similar to a cold with sneezing, congestion, runny nose and sinus pressures.

Allergic rhinitis is caused by an allergic response to airborne substances, such as pollen – unlike a cold which is caused by a virus. The time of year you get hay fever depends on what airborne substance you are allergic to.

Hay fever does not mean that the person is allergic to hay and has a fever. Hay is hardly ever an allergen, and hay fever does not cause fever.

Although hay fever and allergic rhinitis have the same meaning, most lay people refer to hay fever only when talking about an allergic reaction to pollen or airborne allergens from plants or fungi, and understand allergic rhinitis as an allergy to airborne particles, such as pollen, dust mites or pet dander which affect the nose, and maybe the eyes and sinuses as well.

The rest of this article focuses on hay fever caused by pollen and other airborne allergens that come from plants or fungi. Hay fever caused by pollen is also known as pollinosis.

Some people are only mildly affected by hay fever and rarely reach a point where they decide to seek medical advice. However, for many, symptoms may be so severe and persistent that they are unable to carry out their daily tasks at home, work or at school properly – these people will require treatment. Treatments may not get rid of the symptoms altogether, but they usually lessen them and make it easier to cope.

As with other allergies, the symptoms are a result of your immune system mistaking a harmless substance as a harmful one, and releasing chemicals that cause the symptoms.

It is estimated that about 20% of people in Western Europe and North America suffer from some degree of hay fever. Although hay fever can start affecting people at any age, it generally develops during childhood or perhaps early adulthood. The majority of hay fever sufferers find their symptoms become less severe as they get older.

What are the symptoms of hay fever?

Symptoms of hay fever may start at different times of year, it depends on what substance the patient is allergic to. If a person is allergic to a common pollen, then when the pollen count is higher his symptoms will be more severe.

Common symptoms include:

• Sneezing
• Watery eyes
• Itchy throat
• Itchy nose
• Blocked/runny nose

Severe symptoms may include:

• Sweats
• Headaches
• Loss of smell and taste
• Facial pain caused by blocked sinuses
• Itchiness spreads from the throat, to the nose and ears

Sometimes hay fever symptoms can lead to:

• Tiredness (fatigue)
• Irritability
• Insomnia

People with asthma may find that when hay fever symptoms emerge their wheezing and episodes of breathlessness become more severe. A significant number of people only have asthma symptoms when they have hay fever.

What are the causes of hay fever?

Hay fever occurs when the immune system mistakes a harmless airborne substance as a threat. As your body thinks the substance is harmful it produces an antibody called immunoglobulin E to attack it. It then releases the chemical histamine which causes the symptoms.