Monday 22 January 2018

15 facts about allergies

They can be life-threatening - or at the very least, annoying - and allergies seem to be on the rise around the world. Kathy Donaghy asks experts about the symptoms, triggers and different forms of treatments, and finds out who is more likely to be a sufferer

Allergies can range from annoying to life-threatening.
Allergies can range from annoying to life-threatening.

Allergies are frustrating, restrictive, frightening, and in some cases, life-threatening conditions that seem to be on the rise in the Western world. There are 100 million allergy-related Google searches a year, with hundreds of Facebook pages dedicated to the subject, with people seeking answers. But sometimes the answers are difficult to find among the noise, with conflicting ideas about what's going on.

1 What is an allergy and what isn't?

An allergy is an over-reaction of the immune system in response to something that is normally harmless. Different allergies are distinct conditions and there isn't one test to diagnose all allergies. Accurate diagnosis requires both a test and a medical consultation.

Food intolerances, which can be unpleasant, do not pose the same threats as allergies, which are less common. Allergies occur when someone's body treats a harmless substance - called an allergen - as a threat and the immune system produces an unnecessary response to it.

Intolerance to foods can cause problems such as bloating, stomach cramps and vomiting, but food intolerances are not allergies as they do not involve the immune system. They can be mistaken or self-diagnosed as allergies. People with intolerances can usually eat small amounts of the food to which they are intolerant. However, allergic reactions to foods usually happen quickly and can be life-threatening.

2 Symptoms of allergies

The body reacts to an allergen by releasing chemicals such as histamine from cells in the body. The type of symptom depends mainly on how the person is exposed to the allergen because symptoms usually occur where the allergen has come into contact with the body.

In the case of a food allergy, some of the symptoms include itching or swelling in the mouth or throat, hives anywhere on the body, runny nose and eyes, feeling sick, diarrhoea or vomiting. Exposure to airborne allergens can cause nasal and eye symptoms such as sneezing, streaming eyes and wheezing.

3 Misdiagnosing and self-diagnosing

A comprehensive report published in the UK last year found that middle-class parents were leaving their children malnourished by cutting out entire food groups because of needless concerns about allergies. The report by some of the UK's leading allergy specialists found that many people were increasingly misdiagnosing themselves with allergies and food intolerances leading to a culture of cynicism, which trivialised real complaints.

They found that while 40pc of people claimed to have a food allergy, only 5pc actually did. Likewise the report found that around one third of parents believed their children suffered from food allergies but just one in 20 would pass a clinical diagnosis.

Dublin-based dietitian Sarah Keogh says she meets people who have cut foods out of their children's diets even though their kids didn't have any issue. She says it's really worrying when parents cut out whole food groups like dairy, because of some mistaken belief that they have an intolerance.

4 Food allergies

The most frequently encountered allergies include those to milk, egg, peanuts, tree nuts and seeds, fish, shellfish, soya and wheat.

Sarah Keogh says a genuine food allergy can only be identified with a specific blood test. She says it's not a good idea to get a test to see if you are allergic to 10 or 20 foods.

"You don't do a blanket test. The best thing is to get a medical history taken with a specific blood test called an IgE test to check if you are allergic to a particular food," she says. She points out that if the tests show a person has a food allergy, they must be familiar with the treatment and carry their adrenaline pen. She says because the way the body responds to allergy can be different each time, it's important not to be complacent.

5 Growing out of it

Allergies can come on at any age and be outgrown. Keogh says while some young children will have an allergy to cow's milk or eggs, these allergies are unusual in adults. However, other allergies such as nut allergy are usually lifelong. Why some people outgrow some allergies is not known. Experts believe if the process could be fully understood, it could help find cures.

6 Anaphylaxis

According to the organisation SafeFood, if the allergic reaction to a food is severe it can lead to anaphylactic shock. This is where a sudden feeling of weakness caused by a drop in blood pressure occurs or breathing problems arise where the throat starts to swell up or close.

This can be a life-threatening reaction and requires immediate treatment by adrenaline injection, followed by expert medical assistance.

Anaphylaxis Ireland, the national charity which was set up to raise awareness of this condition and to provide support to people at risk and their families, lists the most common causes of anaphylactic shock as peanuts, tree nuts such as almonds, walnuts, cashews, Brazil nuts, sesame, fish, shellfish, dairy products, eggs, soya, wasp or bee stings, natural latex, rubber and penicillin and other drugs. The organisation has a wide range of information for anyone affected by severe allergies on its website - see

7 Eczema and allergies

Eczema can be triggered by many things including soap or detergent. However, allergens like dust mites, moulds, pollens, foods and pets can also trigger eczema.

8 Drug allergies

These are immune reactions to medicines. Dublin GP and allergy specialist Dr Paul Carson says the most common type of drugs people are allergic to include over-the-counter drugs like aspirin and ibuprofen. He says people with a history of asthma have a greater risk of having an allergic reaction to these drugs than others.

9 Treatment

While avoiding the allergen is the most effective way of avoiding an allergic reaction, we don't live in an ideal world and this can be difficult. Keeping a diary of symptoms can be useful in avoiding triggers. Anti-histamines block the action of histamine, reducing symptoms like itching skin and watering eyes. In the case of hay fever, steroid nasal sprays reduce inflammation. For anaphylaxis, people at risk of experiencing an anaphylactic shock should carry injectable adrenaline in a device. In all cases, the first port of call should be your GP.

10 Myths about allergies

The belief that allergic reactions become more severe each time a person is exposed to an allergen is false. According to a report compiled by Britain's leading allergy experts last summer, lots of factors influence the strength of an allergic reaction, including the amount of allergen and the site of exposure, combined with alcohol, exercise, stress, sleep deprivation and drugs.

11 The most common allergies

Hay fever, or allergic rhinitis, to give it its medical name, affects 20pc of us. The pollen released by plants, trees and grasses around this time of year triggers an allergic reaction in hay fever sufferers leaving them scratching, sneezing, feeling congested and sometimes downright miserable.

According to Dr Paul Carson, experts believe that up to 50pc of the population will suffer to varying degrees with hay fever within the next 10 years.

"There's no one single theory as to why it's on the increase, but the big theory is environmental pollution, particularly the amount of diesel fumes in the atmosphere. Diesel fumes leaching with pollen grains produce a super pollen," says Dr Carson.

The other common allergies include food allergies, house dust mites, animal hair and moulds.

12 Asthma and allergies

It's estimated that 470,000 people in Ireland have asthma and 60 to 80pc of these also have hay fever. Pollen is a big trigger for asthma and grass pollen affects 90pc of those with hay fever. Spokesperson for the Asthma Association of Ireland, Anne Kearney, says there are other things that can make an asthma sufferer's condition worse. These are known as 'triggers'.

"A trigger is anything that irritates the airways and causes the symptoms of asthma to appear. It can be difficult to identify exactly what triggers your asthma as the effects can take up to four to six hours before you notice them, or even longer," says Kearney. She advises asthma sufferers to keep a diary to identify what's triggering their asthma. The big triggers for asthma sufferers are house dust mites, pets, pollens and moulds.

13 House dust mites

Dr Paul Carson estimates that about a quarter of the Irish population are affected by some form of allergy. House dust mites are a common allergen, even though they are too tiny to see. They eat the flakes of skin we constantly shed. They occur in every home and they are no indication of the cleanliness of our homes.

They're found in furniture, on carpets and especially on beds. We breathe in their waste products, which may cause an allergic response in a person's airways. Signs of allergy to dust mites may include wheezing when you're hoovering or when you enter a dusty house.

People affected by dust mites should remove all carpets and replace them with hard flooring if possible, and use barrier coverings on their mattress, duvet and pillows. According to the Asthma Society of Ireland, vacuum cleaners with HEPA filters are much more effective at picking up the house dust mite and do not scatter the dust. The society also advises keeping soft toys to a minimum and wash at them at 60 degrees Celsius on a weekly basis.

14 Pets

Dr Paul Carson says the most aggressive allergic reactions is to horse hair, but cat and dog hair are allergens too. Avoiding pet allergens is impossible as they are found in so many environments. However, the Asthma Society says unfortunately cats are not a good choice of pet for families who have members with allergies.

It says other pets do not seem to produce such potent allergens but dogs, rabbits, guinea pigs, hamsters and even mice can cause problems for some people.

15 Moulds and fungal spores

Moulds release tiny seeds called spores into the air which can trigger asthma symptoms in some people. Mould spores are found in damp places - from piles of autumn leaves and woody areas to bathrooms, kitchens and even piles of damp clothes. For people suffering from mould allergies, making their home a mould-unfriendly place is the key. It's important to control the amount of moisture in the air - dehumidifiers will help.

Mould can thrive in warm, damp bathrooms and humid kitchens. A clean surface isn't a breeding ground, but those with soap scum or grease are.

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