ASK LIZA GEDDES what she can't eat, and she takes a deep breath: "Dairy, yeast, wheat, sugar, anything artificial - which includes colourings, E-numbers and artificial flavourings - aspirin and penicillin." It may not seem like such a long list to some, but when you realise that bread, pasta, cheese, chocolate, wine, beer and most of life's culinary pleasures are therefore out of bounds, it's hard to imagine how she continues to exist, writes Fiona McCann

Geddes first noticed her skin becoming irritated when she was about 14, but put it down to heat rash. It was only when she visited an allergy specialist that she realised what the problem was. "He told me, 'You've got some food intolerances'. Then he started reading this list and I just stared at him, thinking he was joking," she recalls.

Her immediate reaction was denial, but her symptoms got worse. "I had hives and rashes, but then I got eczema on my leg from it, and I started sneezing violently, itching, my eyes started going red, I was welling up," she says. "I also got tired, low in energy, and if I ate bread four or five days in a row, my immune system would be weakened, so I'd end up getting a bit of a cold." With her reactions becoming too aggressive to ignore, Geddes cut out all the offending food for a two-year period in her teens, hoping that if she got rid of them entirely for a while, she would eventually be able to reintroduce them.

"The first thing I had after that two years was a KitKat, and it was this amazing feeling. I thought, 'Oh my God! What have I been missing?'. About half an hour later I was sneezing."

Sneezing and hives may sound bad enough, but for six-year-old Iarlaith Crewe, the consequences of straying onto his banned foods list can be much more serious. "About a week after his second birthday, I gave him peanut butter," remembers his mother, Clare O'Brien. "Within about 10 to 15 minutes he was telling me he was sick. He started to get a tummy ache, and then his face started to go red." O'Brien rang her GP immediately, and was told to give her son an antihistamine, but once she saw he was having difficulty breathing, she took him to the A&E. "They took him in immediately and gave him adrenaline and within 20 minutes he was fine again."

Iarlaith has anaphylaxis, the medical term given to a severe reaction which in its most extreme form can have have potentially fatal consequences. The good news is that if adrenaline is injected speedily enough after the reaction begins, the process can be reversed and, as in Iarlaith's case, the sufferer can make a total recovery.

The downside is that Iarlaith, who is also allergic to egg, now has to carry an adrenaline shot with him everywhere he goes. Before he began school this year, O'Brien had to show his teachers how to administer it.

"He was the first child in their school to have anaphylaxis so it was completely new to them," she says.

It's not just his teachers that are affected, however. "For a play-date after school, I have to make sure the other mother is aware of his allergy and is okay with it," says O'Brien.

Iarlaith is not alone. Statistics suggest that some 5 per cent of Irish children and 3 per cent of adults suffer from food allergies. According to Dr Paul Carson, an allergist who helped set up the Allergy Foundation of Ireland, the number of those with life-threatening nut allergies could be as high as one in 50 children, while he says 10 per cent of children and young adults have more than one allergic disorder.

"There is an allergy epidemic," he says. While theories abound over what has caused the rise in children reporting allergic reactions to foods, the most important thing, according to Carson, is to get medical confirmation of any suspected allergies. Two tests - the skin prick test, and one which involves taking a blood sample - are used to detect allergies. "These are the only orthodox tests," Carson stresses, adding that parents should have any suspected allergies verified by one or the other.

Kieran Haughey is a trained kinesiologist, who has been practising and teaching for eight years. An alternative treatment that purports to isolate any foods inhibiting the body from functioning optimally, kinesiology involves testing for intolerances by placing food samples on a person's chest, and testing their muscle response.

"An allergy is a true medical condition, we are not talking about that type of response," specifies Haughey. He says there have been positive results for clients who have removed the foods highlighted through kinesiology from their diets. "People come back and tell me they're feeling more get up and go, they're feeling more motivation, they're feeling they can have clearer thinking, less tiredness all the time, they're waking up refreshed, they're sleeping better," he says. "We're dealing with these things day in and day out, and maybe they're things that people won't go to the doctor with, but they are things that inhibit their enjoyment of life."

Despite the rise in food allergies, Carson warns against paranoia. "There is real food allergy, obviously, and there is the perception that there is a food allergy, and very often this is reinforced by people as various as grannies, uncles, child minders, chemists, or homeopathists.

"The poor mum is very often both confused and distraught and isn't sure what to do," he says.

He cites cases in a recently published medical journal of children in Britain being diagnosed with rickets - a disease caused by vitamin D deficiency or lack of calcium - because parents had cut out too many important foods from their diets out of fear of allergies.

In some cases, however, the mother's instinct can prove the most reliable of all. Malachi Quinn was born in 1971, when the concept of food allergies and intolerance was still relatively unknown here. When he came off breast milk and was put on cow's milk as a nine-month-old baby, his mother noticed he wasn't thriving as he should.

"I was taken into Crumlin's children's hospital, and I spent three weeks there while they did tests, and they couldn't figure out what was wrong," he says.

"My mother kept apparently telling them that she thought it was the milk, and they told her not to be crazy."

His mother eventually removed him from the hospital and switched him to soy milk. "I was taken off all dairy products and eggs, and they noticed an instant improvement in me." Quinn stayed off dairy until well into his teens, and then reintroduced some products slowly, although he still keeps dairy consumption to a minimum.

"I didn't know it was called lactose intolerance," he recalls of his dairy-free childhood. "I just got used to saying at kids' parties that I didn't eat cream." Quinn was lactose intolerant when many of the dairy alternatives now available were not so easily found on Irish shelves. While Irish eating habits are changing and there is a broader range of foodstuffs available, it can still be difficult for those with problems to keep a balanced diet.

"Up until the mid or late 1990s I felt like I was living in jail, with just water and rice or porridge," recalls Geddes. "My diet was very, very boring." Thankfully things have changed. "What saves me is spelt bread. Then soy milk, plus a lot of health food shops will have sugar-free and yeast-free cornflakes, so I'm okay for breakfast."

There are still challenges, however. "Lunchtime is my hardest part of the day. If I could eat bread, I'd be really happy," she sighs. She also finds it difficult to maintain a healthy weight. "I would like to be half a stone heavier," says Geddes, "but with this diet you actually can't put on weight."

Packing for holidays brings its own difficulties. Where the rest of us prioritise a toothbrush and passport, Geddes has to think about food. "I always make sure when I'm going away that I have Flora with me and a supply or Ryvita or peanuts," she says.

Iarlaith's food allergy has also meant some serious adjustments. "I had to contact every manufacturer of everything we would eat here, and get their labelling policies," says his mother.

Eating out can be extremely challenging, so she has to ensure she always has food for Iarlaith with her. "If he's going to a party in someone's house, he will bring a party bag with him himself, so he can just eat his own things," she explains.

O'Brien says joining the Irish Anaphylaxis Campaign (www.irishanaphylaxis.org) helped her cope with the huge changes to her life since Iarlaith's diagnosis.

She now works for the campaign, explaining to her son that her decision to do so was made so she could help people whose lives are made more difficult because of their allergies. "But I have allergies, Mum, and I have a great life," was his response.

For Geddes, however, there are still many foods she misses and, having tried all sorts of treatment, she is hopeful that somebody out there will find a remedy for the food intolerances that have inhibited her life. "You never know, someone reading this might know of a miracle cure," she says hopefully. "One less allergy, that's all I ask for. Wheat, sugar, dairy - I just want one of them back!"

Allergic versus intolerant

A food allergy involves the immune system, and how it responds to certain foods. A food intolerance tends to involve the digestive system.

Symptoms and triggers can overlap, though allergies can trigger a more acute response.

Symptoms of allergies include shortness of breath, chest pain, itchy skin, nausea, sneezing and anaphylaxis. Symptoms of intolerance include bloating, cramps, palpitations, headaches and heartburn.

Common food allergies include peanuts, eggs, tree nuts (walnuts, pecan nuts and almonds) fish and shellfish.

Common food intolerances include yeast, dairy products, monosodium glutamate and caffeine.