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According to Allergy UK: sufferers have tripled in the last 20 years, and the figure is rising about 5 per cent every year.

'At some point a person becomes sensitised to a particular allergen. This could be a food substance, dust mites or pollutants, among many others.

'The body produces an antidote (antibody) against the allergen. Now the body is ready to fight back the next time it's exposed to the allergen,' says Lindsey McManus, spokesperson for Allergy UK.

'When the person comes into contact with the allergen again, the body will produce antibodies to try and fight it off.

'This can cause an allergic reaction – involving the release of chemicals, such as histamine, leukotrienes and prostaglandins. This causes allergic symptoms – such as a itching, swelling, and hives,' she says.

While some people may get a runny nose – for others allergies can be dangerous, even life-threatening.

But if you know your triggers and how to control your symptoms, you can have a positive impact on the effect they have.

There's a huge range of food stuffs that can cause an allergic reaction.

In principle, you can be allergic to all kinds of food. But reactions to the following are common:

Food allergies affect 2 per cent of adults and around four to 5 per cent of children.

Eczema, also known as dermatitis, is a condition where the skin is damaged allowing allergens, such as pollen and animal dander, to get under the skin and react with an overactive immune system.

Eczema mainly affects young people: 85 per cent of children will develop eczema to some extent before the age of five – and in around two-thirds of people, the condition will resolve itself by puberty.

Cats, dogs, rabbits and horses can all cause allergic reactions – such as rhinitis (hay fever) and asthma.

The reaction isn't caused by the animals themselves, but rather allergens in the saliva, urine or dander from their fur.

Pets are one of the main causes of allergies in the home, with 50 per cent of asthmatic children sensitised to the allergens of cats and 40 per cent to dog allergens.

'Hay fever or allergic rhinitis – an allergy caused primarily by pollens and spores – affects between 1 in 10 and 1 in 14 of the population,' says Dr Apelles Econs, medical director of Allergy Medical UK.

'Most often hay fever starts during teenage years and lasts until the person is 30 or 40, after which the allergy tends to wear out because the sufferer becomes more tolerant,' she says.

Contact allergy can be caused by a number of substances that come into touch with the skin, including metals such as nickel, perfumes, glues and dyes.

They can cause swelling, itching and dermatitis.

Asthma is caused by a combination of genetic predisposition and exposure to certain triggers that can be different for each individual.

The immune reaction causes the airway walls to become tightened and inflamed, which makes the airway smaller and causes breathing to be difficult.

With stings, you can get a localised reaction – where an area of your body may swell up, and it can become incredibly itchy and painful.

However, for other people the allergic reaction can spread, and it can be a trigger for anaphylaxis.

Sting allergies can affect anyone, but they are most common in gardeners and bee-keepers.

Hives (also known as urticaria or nettle rash) is composed of reddish itchy weals or swellings in the skin, similar to those resulting from contact with stinging nettle.

The condition is relatively common, affecting one in five people over their lifetime.

'Dietary triggers include foods that contain salicylate, such as fruit, vegetables or nuts. But the heat, the cold and pressure can also trigger urticaria,' advises Lindsey McManus.