Types of allergies

Allergic Rhinitis (Hay fever)

Hay fever is caused by pollen, fine particles produced by trees, grass and weeds to fertilize other plants, especially in the spring, summer and autumn. Pollen is carried by the wind, sometimes for miles at a time, and often enters your nose instead of finding its intended destination. People who are allergic to one kind of pollen are often allergic to many other kinds. This can result in an almost endless cycle of suffering as the seasons change and different types of pollen are released in the atmosphere.

Symptoms of allergic rhinitis include; sneezing, nasal irritation and congestion; itchy nose, palate and throat; a runny nose that is normally clear and copious in volume; and itchy, watery red eyes. It is often mistaken for a cold, until it is apparent that it has gone on for too long.

Animal allergies

Many people have allergies to dogs, cats and other furry pets. People with asthma are especially vulnerable. The cause is proteins in the animal's saliva, skin oil, dander (dead skin flakes) and urine. The immune system may also be reacting to pollen and mould spores carried on the animal's fur, or to fleas and fleabites. Allergies to pets may take over two years to develop, so it is possible that you or a family member could experience symptoms with a pet that's not a newcomer to your home.

Symptoms of animal allergies depend partly on the type of exposure. Airborne dander can produce an itchy nose, congestion, itchy eyes, sneezing and shortness of breath. Direct skin contact with fur or saliva can produce different symptoms, most notably itchy, red, raised bumps on the skin (nettle rash).

Food allergies

Food allergies are sometimes confused with food intolerance. For example, an intolerance to lactose, a component of milk products, can cause vomiting and diarrhoea. In fact, only 1 percent of adults and 3 percent of children have true food allergies. If you suspect that you or your children are allergic to a type of food, it is important to have an accurate diagnosis from your doctor or a specialist in allergic diseases. A lot of people avoid eating things to which they mistakenly believe they are allergic.

The majority (about ninety percent) of all food allergic reactions are cause by eight foods: milk, eggs, wheat, peanuts, soy, tree nuts (such as walnuts, pecans and almonds) fish and shellfish. The allergic person reacts to proteins in these foods that are not broken down by cooking or digestion. Children usually outgrow allergies to milk, eggs, and soy, but are less likely to shake an allergy to peanuts or tree nuts. As with other types of allergies, you're more likely to have a food allergy if one or both parents had allergies.

It is also possible to have a cross-reacting allergy. For example if you're sensitive to birch pollen, eating hazelnut and other nuts, apple, pear, cherry, walnut, almond, plum, kiwi, potato peel, tomato and carrot can cause itching and swelling in the mouth. Similarly, grass cross-reacts with beans and green peas causing the same reaction.

Symptoms of food allergies include:

• nausea
• vomiting
• abdominal cramps
• diarrhoea
• a flushed face
• itchy skin and a rash
• headache
• tiredness and irritability
• a prickly sensation in the mouth and on the lips
• respiratory symptoms such as sneezing, watery eyes, coughing and wheezing are distinctly less common.

These symptoms can develop within minutes of exposure to the foods Very rarely anaphylactic shock can occur, which is a circulatory collapse that needs acute treatment with adrenaline. Symptoms which are mild one day can be life threatening the next because of the danger of suffocation or anaphylactic shock. You should never expose yourself to a reaction by eating foods you know you are allergic to just to avoid putting people to extra trouble or causing embarrassment. If you begin to have difficulty breathing, you need medical treatment right away.