Allergic rhinitis - not just a runny nose

1. The house dust mite. This is a microscopic creature, which feeds on flakes of human skin and is present in every household, however clean, but is only a problem if you are allergic to it. It causes symptoms all year round.
2. Pollens, moulds, animal fur and dander are other common allergens that tend to cause seasonal and more localised problems.

All of these allergens have to be inhaled to cause a problem, and affect up to 40 per cent of the population.

Prevention

• Avoid keeping furry animals as pets if you are allergic to them.
• Replace pillows and quilts containing animal feathers with synthetic stuffing.
• To reduce house dust mite numbers remove dust-collecting items such as carpets and curtains, particularly in the bedroom. Vacuum and turn your mattress regularly, cover the mattress with a spongeable cover and wash bed linen regularly.
• Some people suggest placing soft toys in the freezer every six months to kill the house dust mites.
• To prevent the symptoms of hay fever avoid areas with long grass or where grass is being cut. In summer keep the doors and windows closed and spend as much time in air-conditioned buildings as possible. Try to stay indoors when the pollen count is highest, such as late morning and early evening. Keep the lawn mowed short to prevent grasses flowering.
• Wear sunglasses to avoid pollen getting in your eyes, and shower when you get home to remove pollen from your face and nose.
• To avoid moulds keep your house well-ventilated and free from damp.

Treatment
Antihistamine drugs (tablets or syrups) prevent symptoms such as itching, sneezing, and a runny nose. Many are available, both over the counter and on prescription. The most recently developed antihistamines such as Desloratidine and Fexofenadine are less sedating, and less likely to interact with other drugs than the older types of antihistamines.

Topical nasal steroid sprays such as Beconase and Nasonex are very effective if used correctly. They should be used according to the instructions in the pack and are most effective for hay fever if you start before the pollen season starts and continue until after the season finishes. The steroid is not absorbed into the bloodstream enough to give any side effects and so is safe for everyone.

Steroid injections are also available and will provide relief for up to six weeks. They are not used routinely because of the potential side effects of steroids, particularly in children.

Immunotherapy Immunotherapy attempts to alter the way a person reacts to an allergen and has been shown to be particularly effective for hay fever. There were concerns about the safety of this injected treatment, and in 1986 strict guidelines were laid down to restrict its use to specialised centres. The recent development of an oral 'vaccine' for hayfever, called Grazax may in the future bring safe immunotherapy to the masses. It needs to be taken daily, starting at least 4 months in advance of the hayfever season, and continued throughout the season, to be effective.

Who is affected?
There is a lot of evidence now to show that allergic conditions are getting more common. There are several plausible theories for this, for example, more house dust mites are found in houses with central heating, wall-to-wall carpeting and double glazing. Another theory is that as children are exposed to fewer childhood infections their immune systems become more active in other directions. Certainly the numbers of people with rhinitis, asthma and eczema are on the increase; it is estimated that by 2015, half the population of Europe will suffer some kind of allergy.