Hay fever is a type of allergic rhinitis (irritation and inflammation of the membranes of the nose) that is characterized by itching, sneezing, runny nose and nasal congestion. Although it is not life threatening unless accompanied by severe asthma or severe allergic reaction (anaphylaxis), the impact on everyday life can be severely limiting. Approximately 20% of the world’s population is known to have hay fever.
Hay fever affects the nose, sinuses, throat and eyes. It is usually seen in spring and summer, when there is more pollen in the air. People with hay fever can experience symptoms in different part of the year, depending on which pollen they are allergic to.
Symptoms of hay fever occur when a person’s immune system overreacts to a normally harmless substance ( in this case pollen). When the body comes into contact with pollen, defense cells in the membranes of the nose, mouth and eyes release histamine, a chemical that triggers the allergic response seen in patients with allergies.
FACT CHECK ABOUT POLLEN
Hay fever symptoms are likely to be worse if the pollen count is high. The pollen count is the number of grains of pollen in one cubic meter of air.
Air samples are collected in traps set on buildings two or three storeys high. Taking samples from this height gives a better indication of the pollen in the air from both local and distant sources. Traps on the ground would only collect pollen from nearby trees and plants.
The air is sucked into the trap and the grains of pollen are collected on either sticky tape or microscope slides (glass plates). The pollen is then counted. Samples are usually taken every two hours, and the results are averaged for a 24-hour period.
The pollen forecast is usually given as:
- low: fewer than 30 grains of pollen in every cubic metre of air
- moderate: 30-49 grains of pollen in every cubic metre of air
- high: 50-149 grains of pollen in every cubic metre of air
- very high:150 or more grains of pollen in every cubic metre of air
Hay fever symptoms usually begin when the pollen count is over 50. The pollen count is usually given as part of the weather forecast during the spring and summer months.
- From January to April, pollens from trees are the most common cause of hay fever.
- From May to August, pollens from grass are the most common cause of hay fever.
- During the autumn, hay fever may be caused by weeds such as nettles and docks, late flowering plants, and mould and fungal spores.
SIGNS AND SYMPTOMS
Hay fever symptoms vary in severity and people may experience different levels of severity than others, depending on the weather conditions and the pollen count. Symptoms may start at different times of the year depending on which types of pollen a person is allergic to.
The symptoms of hay fever include:
runny or blocked nose
itchy, red or watery eyes (also known as allergic conjunctivitis)
an itchy throat, mouth, nose and ears
the loss of your sense of smell
facial pain (caused by blocked sinuses)
While symptoms of hay fever may be mild, they can interfere with your sleep and your daily activities at school or work.
If you have asthma, your asthma symptoms may get worse when you have hay fever. Sometimes, asthma symptoms only occur when you have hay fever. These symptoms include:
shortness of breath
The management of hay fever consists of the following 3 major treatment strategies:
Environmental control measure and allergen avoidance: keeping exposure to allergens such as pollen, dust mites and mold to a minimum.
Pharmacological management: Use of oral medication (antihistamines/anti-allergy medication) along with decongestants to relieve symptoms. Nasal steroids may be prescribed to patients with long-term symptoms.
Immunotherapy: treatment with antibodies may be initiated in patients with severe disease, poor symptom control with other medication, or other long term illnesses which may complicate allergic rhinitis.