Seasonal irritations

Runny nose, watery eyes and sneezing? It sounds like hay fever. But you don't get that in the depths of winter, do you? Allergies don't disappear with the sun at this time of year. The pollen may have gone but there are plenty of other winter-loving allergens left to irritate you.

An allergy can start at any time in your life. The number of allergy sufferers in the UK has quadrupled in 20 years to around half the population and that figure is still zooming up. According to Dr Chris Corrigan, allergy expert at Guy's Hospital, the problem has reached epidemic proportions.

So if you're feeling off-colour this winter, don't assume it's a cold or the flu. You may be allergic to one of the following...

Dust mites

These microscopic creatures live wherever there's dead skin - their staple diet. Your carpets, bedding and clothes are teeming with them.

It's worse in winter: Mites like it hot and wet, so centrally heated houses and offices are a perfect breeding ground. Cold kills them, so open windows.

What happens: The allergen is the proteins the mites excrete. The nose and mouth react to these by releasing histamine, which cause hay fever-like symptoms. Asthma can also be aggravated. Direct contact with the skin, for example through a pillow, can also cause eczema.

Prevention: Some sprays eliminate mites (Total Hygiene, £14.99), but they are often insecticides and can irritate asthmatics. Put your bedding and pillows in the freezer during the day to kill the mites living in them. Anti-allergy bedsheets are also available (£44 from www.medivac.co.uk).

Nuts

Any food can cause an allergic reaction but nuts are the most common. One in ten children in the UK now suffers from nut allergy (one in seven in the US).

It's worse in winter: Nuts are ubiquitous at Christmas, whether they're in a bowl on their own or a constituent of festive cooking (Christmas puddings, stuffings and so on).

What happens: The food causes a release of histamine from the body's cells that are in contact with the food. This can lead to swelling, constriction of the chest and rashes. In severe cases, it leads to anaphylaxis (see factfile).

Prevention: Avoid nuts or foods which contain them. If you're allergic, there's nothing you can take to enable you to eat nuts without suffering the consequences. Luckily, reactions are mild in most cases.

Animal fur

Around one in ten people have this allergy. You don't have to own pets to be exposed to the allergen. Recent studies have found it in unlikely places, from trains to cinemas.

It's worse in winter: Admittedly, animals don't moult as much in colder months, but cats and dogs tend to spend more time indoors with us during winter.

What happens: Proteins deposited on the hair - either secreted through the animal's skin or from its gut and mouth when it licks itself - cause an allergic response, which is much the same as with dust mites, causing hay fever-like symptoms.

Prevention: Keep animals out of the house and clean daily with an allergen-filter vacuum (£235 from Dyson). Allergy sprays can neutralise the allergens (£17.95 from www.allergymatters.com).