The Times
John Naish
Gerry Gajadharsingh writes:
“An interesting update on the difference between allergies and intolerances. The stats haven’t changed in at least 20 years, in that it’s still only 3% of the UK population who have a true clinical immune mediated allergy.
An interesting quote from the immunologist featured in the article.
“About half of the patients who come to my clinic are not allergic at all,” she says. “For every person who has a food allergy, there will be another six who believe that they are allergic. About 10 per cent of the UK population are labelled by their family doctor as allergic to penicillin. Some 90 per cent of cases are thought to be incorrect.”
“Much of what people think is food allergy is actually intolerance,”
“Food intolerances, by contrast, are a reaction that doesn’t involve the immune system. The problem is digestion. The commonest intolerance is for lactose.
“Allergy is 99 per cent caused by protein. Intolerance is caused by lactose or a sugar,”
All the food we eat provokes a degree of endotoxaemia, a local inflammatory reaction in the gastrointestinal tract. Usually, our bodies bio and neurological/immune regulators can normally keep this under control. The issue is when we over consume certain foods. It’s one of the reasons why in the UK, many people are intolerant to too much cows’ dairy and wheat produce, because that is such a large part of the population’s diet. The key, as always, is a balance and variety in your diet i.e. don’t eat the same thing every day, this really minimises the risk of developing intolerances in the first place.
Even if there is a suspected food intolerance avoiding that food for up to 6 weeks and gradually reintroducing it at a very minimal level often allows people to build up a tolerance to that particular food.
We offer via TDL, a test for lactose intolerance, TDL Genetics offers a genetic test to assist in the diagnosis of primary lactose intolerance in both children and adults, which historically has been difficult to formally diagnose.
They also offer a numerous, IgE mediated tests to confirm true allergy, sometimes a bit like a needle in a haystack, unless there is a real suspicion of the food that may be causing a true allergy and of course coeliac testing for gluten sensitivity.”
Dr Sophie Farooque was working long, pressured hours as a junior hospital medic when she developed a nasty bout of sinusitis. Her GP prescribed penicillin to tackle the infection. She also took ibuprofen to quell the pain overnight and went back into work.
As Farooque walked on to the ward, the consultant saw that her face had become swollen and her neck and arms were covered with red hives. He told her she looked like Shrek, then proclaimed that she would frighten his patients and sent her home.
“On the way out, he said I was clearly allergic to penicillin and that I would be a good teaching case for the medical students,” she says. “It was only several years later that I realised he was completely wrong. I hadn’t suffered an allergic reaction at all.”
By then Farooque was well on the way to being one of the UK’s leading allergy experts. In 2001 she was the first doctor in the UK to enrol on a rigorous five-year allergy-specialist training programme. Now a consultant, she leads allergy services at St Mary’s Hospital in Paddington and is on the council of the British Society of Allergy and Clinical Immunology.
As well as diagnosing and treating allergy, Farooque is also busy undiagnosing people who are convinced — often thanks to a medical diagnosis — that they have serious allergies to food or medicine when in fact it is not true.
“About half of the patients who come to my clinic are not allergic at all,” she says. “For every person who has a food allergy, there will be another six who believe that they are allergic. About 10 per cent of the UK population are labelled by their family doctor as allergic to penicillin. Some 90 per cent of cases are thought to be incorrect.”
If anyone can persuade people to let go of their allergy fears, it’s Farooque. Rather than the cartoon-caricature coldly strict consultant, she is comfy-jumpered and warmly jovial, a personality to reassure and cure. Now Penguin is publishing her book explaining what allergies are and, just as important, what they aren’t.
Farooque now knows that penicillin did not provoke her outbreak of hives and swelling. “That was caused by infection,” she says. “It had nothing to do with an allergy. Mast cells [allergy cells responsible for immediate allergic reactions] in your skin can release histamine in response to infection, which causes inflammation and consequently hives. Taking NSAIDs [non-steroidal anti-inflammatory drugs] such as ibuprofen can also kick off your mast cells.”
Such hives, the medical name for which is urticaria, can often be treated successfully with antihistamines. Yet they are so common, and so often mistaken for allergic responses, that Farooque calls them the “biggest red herring of them all”. She adds that stress, be it chronic or sudden, can also spark attacks.
Currently, though, it’s the difference between food allergy and food intolerance that causes most confusion in the UK. According to NHS data, about 3 per cent of the UK population have classic clinical food allergies and might be at risk of potentially life-threatening allergic reactions. Yet social surveys in the UK repeatedly find that a third of people think that they suffer a food allergy that has not been diagnosed medically.
“Much of what people think is food allergy is actually intolerance,” Farooque explains. “Allergy is your immune system responding to something that’s harmless as though it’s harmful, such as peanut, milk or seafood. You get itching, sneezing, hives — and in rare extreme cases life-threatening anaphylaxis.
“Food intolerances, by contrast, are a reaction that doesn’t involve the immune system. The problem is digestion. The commonest intolerance is for lactose. If people don’t have the gene to break down lactose, you get diarrhoea,” she says.
“Allergy is 99 per cent caused by protein. Intolerance is caused by lactose or a sugar,” Farooque adds. “Intolerance is not the same level of risk as, say, a peanut allergy where a tiny amount can cause severe reaction. Intolerance is more quantity dependent. With lactose, for example, you can have just a bit of butter or cake and it won’t set off a reaction. Intolerance doesn’t kill people, as far as I know.
“I have intolerance with milk. I can drink one skinny latte, but two can set me off. Having a lactose intolerance is not an issue for me, but clearly intolerances are unpleasant and can affect quality of life, especially if it’s on the far end of the scale.”
Seafood is another item that can prompt intolerance, Farooque says. “I see people who sometimes have had really bad vomiting or diarrhoea after eating it. There must be mechanisms that we don’t yet understand. These things resolve and don’t normally hospitalise people. The best thing to do is avoid the problem food.”
As for telling the difference between allergy and intolerance? “A lot of it is about the timing of the reaction’s onset and how long it carries on for,” she explains. “Allergy is immediate. If you wake up in the morning with it, having not eaten or taken any new medicine, usually it’s not allergic. If the response comes two or three hours after taking a suspect medicine, then it’s not allergy because that’s too long. If it carries on for a week, it’s not likely to be an allergy.
“Not every hive is an allergy and not every itch is an allergy. Some 60 per cent of kids brought in with food allergy have non-allergic hives,” Farooque says, but adds: “Clearly intolerances are stressful, especially if it’s affecting a baby, so do see a doctor about them.”
Meanwhile, Farooque would love to see doctors’ diagnoses of penicillin allergies vastly reduced, not least because of her own experience. “In an ideal world I would delabel everyone with penicillin allergy and have them tested properly,” she says.
“The majority of people who get labelled penicillin-allergic acquired the diagnosis following a rash that occurred after taking penicillin in childhood or adulthood. People get hives when they are unwell and blame it on the medicines. The moment there’s a sniff of a medication allergy, doctors are reluctant to prescribe that medicine again.”
Being wrongly labelled with penicillin allergy can be dangerous, Farooque warns. “If you don’t have the allergy but also don’t receive penicillin for things such as hard-to-treat chest or urine tract infections, your health can seriously be impacted.” She cites a Pennsylvania State University study of more than 26,000 Covid-19 patients, published in The Journal of Allergy and Clinical Immunology: In Practice, which found that patients labelled as penicillin allergic were significantly more likely to be put on ventilators in intensive care.
“That was surprising, as Covid-19 is a viral infection and therefore antibiotics are not directly useful,” she says. “One explanation is that the virus can make patients more vulnerable to bacterial pneumonia. If penicillin is off limits, bacterial pneumonia is harder to treat.”
In the realm of severe allergies — food reactions that can cause lethal anaphylaxis — Farooque is delighted to bring some good news. “We were just about to publish the book with me lamenting how a new oral therapy called Palforzia wasn’t available in the UK outside research settings. Then suddenly NHS approval came through just before Christmas, so I was happy to rewrite that.”
Palforzia capsules contain 0.5mg of peanut protein that has been pharmaceutically graded. It is given in strictly controlled doses to children with severe peanut allergies with the aim of helping their bodies to develop some level of tolerance to the allergen, so that if they accidentally ingest it in food it won’t send them into anaphylactic shock.
“It’s not a cure, but it reduces the reaction. The goal is not that your children can have a peanut-butter sandwich,” she says. “Prior to Palforzia’s approval people had been trying to desensitise children by giving them fragments of chopped-up peanuts. But not all peanuts have the same amount of allergen, so it could be dangerous.
“It’s a faff because the kids can’t sleep or exercise straight after the Palforzia dose and the side effects are an itchy mouth and stomach pain. But it’s good for families where peanut activation really affects their quality of life.
“There can also be a problem with treatment fatigue as kids grow older, and it’s not good for kids with multiple food allergies, but it is still lovely to have this option.”
Other forms of immunotherapy may be used for other allergies, such as severely debilitating hay fever. But again Farooque says they are problematic. “Jabs involve eight weeks of having an injection of something into your arm that makes your arm itch. You have to sit for an hour afterwards at the hospital in case you have a serious reaction,” she explains.
“The alternative is a tablet under the tongue, for children who don’t like injections. You have to do this for three years, taking these tablets every morning and getting reactions such as an itchy mouth. And you have to keep taking anti-allergy medicines as well.
“Immunotherapy is the final rung of the ladder, for the most severe cases,” she stresses. “You only do this for people who had to go through everything else and it didn’t work.”
For all its challenges, however, allergy medicine brings Farooque great joy. She discovered the specialism when her professional life was at a difficult juncture.
“I took time out from work after my qualifying exams to think about what I wanted to do in medicine,” she says. “Within a few weeks the advert came out for the first NHS allergy post. It was love at first sight. I would not dream of doing anything else. It’s making a difference and improving lives. I’m a happy doctor, which may be a rare thing nowadays.”