Q&A about allergies with Sense About Science

In June 2015, we ran a Q&A about allergies with Sense About Science - they've just released a new guide which aims to make sense of the causes, diagnosis and treatments of allergies.

The guide tackles topics ranging from whether allergies are becoming more common to how to get an accurate diagnosis to allergies that can come and go. The guide was published as allergy specialists and charities warn of the dangers of misinformation and over-diagnosis. More and more people are diagnosed with allergies in developed countries, but what are the best ways to diagnose and treat allergies safely and effectively?

Expert Panel - answering Mumsnetters' questions


Dr Paul Seddon is a Consultant Respiratory Paediatrician at the Royal Alexandra Children's Hospital in Brighton. 

Dr Adam Fox is a Consultant Paediatric Allergist at Guy's and St Thomas' Hospitals Foundation Trust in London - the UK's largest specialist allergy service. He's Chair of the Advisory Board of Allergy UK, Director of Allergy Academy and member of the Anaphylaxis Campaign.

Dr Tariq El-Shanawany is a Consultant Clinical Immunologist at the University Hospital of Wales, Cardiff.  

Dr Samantha Walker is Deputy Chief Executive and Executive Director for Research and Policy at Asthma UK. 

Q&A: Cause and diagnosis | Treatment | Symptoms and how allergies work | Other


Cause and diagnosis

Q. lmnz: I'm interested to know the latest thought/research on how stomach bugs like Norovirus may impact on the likelihood of becoming sensitised to an allergen?

Dr Tariq El-Shanawany

A. Dr Tariq El-Shanawany: This question quickly demonstrates some of the complexity in trying to unpick allergies. The gut microbiome appears to be involved in modifying the risk of developing allergies. However, this is not the same as saying that it determines whether you develop an allergy or not, just that the chance of developing an allergy may be higher or lower.

Norovirus and other such infections may change the gut microbiome, but can have different effects on different people depending on factors both to do with the person and their genetic make-up and the gut microbiome before the infection.

Q. OliveCane: I am convinced my son has allergies because he had antibiotics straight after birth, as a precautionary measure. Is there any association between use of antibiotics straight after birth and multiple allergies?

A. Dr Paul Seddon: In a word, no.

Q. Loraline: I have a severe allergy to tree nuts (have been in anaphylactic shock) and to a lesser extent peanuts. My son is just about to turn two and so far we've kept him away from nuts. My husband has hayfever but no more serious allergies. How and when would you recommend introducing our son to nuts? He has no other issues with any food and only very mild eczema.

A. Dr Adam Fox: Fortunately, it is not hereditary but having allergies generally is. I would advise having your son allergy tested ASAP and if negative you can get on with introducing nuts. Ideally, the time to make this assessment is four to six months when you may be able to prevent nut allergy developing by introducing them into the diet.

Dr Adam FoxQ. LatinForTelly: My son was hospitalised for an anaphylactic reaction to Brazil nuts when he was about 18 months old. He is fine with peanuts, almonds and hazelnuts. He gets stomach pain when he eats baked beans, lentils and chick peas. He gets a rash on his face when he eats tomatoes and some other things, and has one most of the time at the moment on his face. He had moderate to severe eczema as a baby, which is now mild. When he was in hospital, we were told he would be referred to an allergy clinic, but this never happened.

Should he be further investigated, or given he is generally well, is it just one of those things?

A. Dr Adam Fox: I would advise following this up to get a clear diagnosis for the allergies – what he can have and what he can't - otherwise you risk unnecessary restrictions. You also need training around food labelling, recognising and managing reactions as well as repeat testing to see if he has outgrown any of the allergies.

Q. Lovepancakes: Is IgA and IgG combined testing reliable? 

Also regarding these what I think are non-coeliac food sensitivities, why has it taken me and DD years of illness to find out about it and do doctors get enough training in this area? Or are there very few of us with this?

A. Dr Adam Fox: Doctors get very little training in this area despite many people being affected. Just because you don't have coeliac disease doesn't mean you don't have a problem with wheat and many people have non-coeliac gluten hypersensitivity.

Neither IgE or IgG testing will be helpful here – better a good registered dietician to go through stepwise exclusion/reintroduction diets to work out what the problem is.

Q. ssunniebear: I have IBS D symptoms with consultant treatment. I have tried a low FODMAP diet but found that certain symptoms got worse particularly burning feelings in the tummy and I started to vomit. I get rashes on my chest and a saw mouth with ulcers. The dietitian suggested that these symptoms could be caused by allergy. I have not noticed any obvious food triggers and the GI seems reluctant to consider this. Could these symptoms be allergy-related and if so, how would I go about finding the cause?

A. Dr Tariq El-Shanawany: The FODMAP diet does appear to be helpful for some patients with IBS, but unfortunately doesn't help everyone. Mouth ulcers can occur for various reasons and are not always allergy, and the same is true of rashes. One important question is around whether there is a consistent food trigger, and a food diary and symptoms can be helpful in determining whether there is a link with a particular food, or whether there is no pattern.

Q. AllergyMums: What is the relationship between reflux and allergies? Is there any new information on the causes of urticaria? Is patch testing accurate? For intolerances - is there any test or is it down to the patient to figure it out?

A. Dr Tariq El-Shanawany: Urticaria can occur for many reasons, allergies being one, but it can also occur spontaneously and the mechanisms behind spontaneous urticaria are not well understood.
Nearly all tests carry a false positive and false negative rate, which is why interpretation by a qualified individual is important. The key with most tests is to view them as part of the picture, and to consider them alongside the clinical history.

Q. mandmsmummy: My four-year-old daughter has had what the GP says is eczema for ages. It's only in the crease of her elbows and comes and goes. I'm wondering about an allergy, possibly wheat. Is this a possibility?

A. Dr Adam Fox: Unlikely – eczema is genetically programmed and can be made worse by food allergies. However, food tends to be an issue in younger kids, where the eczema is diffuse and treatment resistance and often alongside gastrointestinal symptoms.

Q. OliveCane: I would like to know whether atopy patch test could be used to confirm a delayed allergy and where this type of test could be done?

A. Dr Tariq El-Shanawany: Patch testing can be useful in the investigation of delayed skin reactions. This is usually performed in dermatology departments and involves taping a cap containing the suspected substances to the patient's back for 48 hours and reading any resultant skin changes.

Q. diggerdigsdogs: My son is two-and-a-half years old and has viral induced wheeze/asthma. He has a daily steroid and ventolin as needed (every time he catches a bloody cold but well otherwise). There is a strong history of asthma, eczema, milk intolerance, cat hair and dust mite allergies and hayfever in my family and some in DH's family.

Should I push for allergy testing or to find out if there is any other cause for the viral induced wheeze and why he has such extreme reactions to a cold (he hasn't had a cold that hasn't resulted in a hospital admission) or just wait and see? Is there anything at all that can boost immunity in children like my son? 

Dr Paul SeddonA. Dr Paul Seddon: If your son really has no symptoms in between colds (eg no regular night cough, no salbutamol needed except with colds) it is very unlikely that allergies are a significant trigger for his wheezing, and so even if he has positive skin tests this will not influence his treatment.

Most children with viral induced wheeze don't have a problem with their immunity - if anything, the wheezing is part of a too-vigorous immune response! He may develop other triggers as he gets older, or he may just grow out of the problem as at least 50% do. In the meantime, it would be worth considering the following and discussing with your doctor:

  • Are you getting in early enough and aggressively enough with Salbutamol?
  • Is he on a very low dose of inhaled steroid? (There may be scope to increase.)
  • Would he benefit from daily Montelukast?



Q. Katymac: I have various skin/contact allergies but my GP has told me that contact allergies aren't really allergies - if they aren't, why do they often respond to antihistamines? And could it be possible that my IBS is 'contact' allergy internally?

A. Dr Tariq El-Shanawany: Contact skin reactions are still an immune reaction and can be thought of as an allergy. However, whether it is called an allergy or not doesn't really change the advice or management. If someone with contact dermatitis knows what they are reacting to then avoidance is recommended. If it is not clear whether there is an external trigger or what the trigger is then patch testing by dermatology may be helpful. The understanding of IBS is that this is a separate condition from contact dermatitis.

Q. DoJo: I would love to know if there is ongoing research into the efficacy of using hookworms as treatment for allergies, and indeed other immune system malfunctions?

A. Dr Tariq El-Shanawany: Certainly this is an interesting field, and has helped improve our understanding of the immune system. The hope is that research will identify the important components of this response, leading to new treatments without having to use parasites.

Q. bananaandcustard: My 15-year-old daughter developed a mild milk allergy at 13 with a small positive skin prick test. Her symptoms have always been feeling sick with facial swellings and so we avoid. Her older brother has a list of food allergies since birth and both of them have all environmental allergies. What are her chances of outgrowing milk allergy? What are her chances of developing full blown anaphylaxis and would you advise carrying an epi pen as a precaution?

A. Dr Adam Fox: It's unusual to develop milk allergy at this age and as a result it's hard to predict the course. We know a lot about milk allergy that develops in infancy (and most outgrow by six years old) but it's hard to apply that here.

Anaphylaxis is very hard to predict – we know that kids who have food allergy and asthma, or a history of severe reactions are at higher risk but you can still have a bad reaction without these risk factors. There are other factors to consider too, so this needs to be discussed with your own allergist.

Q. Fozzybear22: My son was diagnosed with cow's milk protein allergy at five months. After regular testing his allergy had reduced by 20 months so we were given the go ahead for a milk challenge. We've got past the baked milk stage as his behaviour deteriorates massively. I spoke to the allergy nurse about this, who said there was no link between allergy and behaviour and to keep with the milk ladder. However, we have stopped every time as it is extremely distressing for him and the rest of the family.

My question, which I've never found the answer to, is do we keep moving up the milk ladder, and if we do this, will he become sensitised to the milk protein over time and his behaviour be less affected? 

A. Dr Adam Fox: Although behavioural issues are not considered as allergic symptoms, sometimes the tummy ache the milk causes can present as a deterioration of behaviour. I would only advocate regular baked milk as a way of speeding up outgrowing of the allergy if the milk is being well tolerated. It doesn't sound like it is so perhaps you should step back for six months before trying again.

Q. lmnz: Your document says that an allergic reaction doesn't make the next more severe. Does sensitisation stop once an allergic reaction occurs?

A. Dr Tariq El-Shanawany: Some allergies are often lifelong (eg peanut), whereas other allergies are often outgrown over time (eg hayfever).

Many factors affect how severe an allergic reaction is: the allergen, the dose of exposure, the method of exposure and also factors to do with the person such as whether they are otherwise unwell. The severity of each reaction will vary according to these factors as well as the underlying allergy.

Sensitisation refers to whether the individual makes specific IgE against the allergen. Allergy refers to whether there is a reaction to the allergen. People can be sensitised but not allergic, which can cause confusion as in this case blood tests can be positive even though the person is not allergic.

Q. ronap23: My 10-year-old daughter has asthma and has tested positive for various airborne allergens. She is recommended to take antihistamines daily. Her asthma is stable and she isn't showing signs of irritation so I am reluctant to give her this medication daily. What are the long term effects from daily use of antihistamine?

A. Dr Paul Seddon: Antihistamines will relieve hayfever-like symptoms (eg runny nose, itchy eyes) caused by airborne allergens but have no effect on asthma symptoms. There are no worrying long term effects of daily antihistamines, but on principle I agree with you that it's best not to take medication daily if it is not needed. I would suggest just giving the antihistamine if your daughter has allergic nose or eye symptoms. Fortunately antihistamines work quickly so they can just be given for symptom relief.

Q. Feckinlego: My son is seven and my daughter is nearly two. As babies they both had reflux and eczema. My son has asthma. They both suffer chronic constipation. Their dietician suspects milk allergy, so we're on a trial of dairy free at the moment, and both children's bowels are working normally. Their paediatrician has said there's nothing to indicate milk allergy and to stop the dairy free diet. How likely is it that they are allergic? No improvement in eczema or asthma.

Dr Samantha Walker

A. Dr Samantha Walker: I suspect your paediatrician is right and the constipation is not an allergy problem; their asthma and eczema may well be but if neither are clearing up on a dairy-free diet then it's almost certainly not the culprit.

Q. lmnz: I've read about the research with large quantities of lactobacillus rhamnosus GG and peanuts in Australia. I am giving my seven-year-old son (hospital confirmed peanut, cashew, pistachio, egg, kiwifruit, dust mites, grasses, cats allergies) a probiotic with this in daily (recommended amount only). Wondering if there is any evidence this is helpful or harmful?

A. Dr Tariq El-Shanawany: It is hard to give specific clinical advice around this issue. There is growing evidence that the gut microbiome may be involved with changing the risk of developing allergies. However, this is different from knowing how best to alter the microbiome. An interesting area, but one on which more research would be helpful.

Q. lmnz: I chose sublingual immunotherapy for my seven-year-old (for dust mites/grass) to make it less traumatic, what's the latest evidence on effectiveness, and could this help other existing allergies, or avoid further sensitisation? 

A. Dr Paul Seddon: There is good evidence for the effectiveness of sublingual immunotherapy for grass allergy. Unfortunately it isn't available on the NHS is many areas of the country.

Q. SirVixofVixHall: I have a wasp sting allergy, which I find really stressful. I did wonder about desensitisation treatment, but is there hope on the horizon of any other treatments?

A. Dr Tariq El-Shanawany: While it is great that in some situations desensitisation immunotherapy offers the chance of treating the underlying allergy, it would of course be preferable if the schedule of treatment could be more convenient. There is the possibility that by combining desensitisation with immune modifiers the schedules could be improved, but as with all medicines these take years to come to market and not all ideas prove possible to translate into an actual treatment.

Q. codandchipstwice: Hi, my nearly ten-year-old has many food allergies stemming from his massively severe birch pollen allergy (no celery, apples, carrots, peaches etc). He is also allergic to some nuts, including peanuts. His hay fever is just awful at the moment too, and has actually tipped into asthma this summer too.

Two questions if I may: Will eating food he's allergic to actually cause him harm? He does love the food he avoids plus many adults don't 'get' that's he's allergic to fruit and veg and just think he's trying it on. And what more can be done to educate as to the impact severe hay fever can have? The school's first reaction to the wonderful weather is to take all classes outside and it is just so awful for him come evening time.

A. Dr Adam Fox: This is oral allergy syndrome. Severe reactions are rare but still best not to eat things that he reacts to. Try peeling the fruit or microwaving it for 10 seconds – this sometimes makes a difference.

Dr Samantha Walker: The most effective treatment for hayfever is a regular nasal steroid spray, taken every day, twice a day, for the whole pollen season. They are safe and well tolerated (although not popular!) in children. Secondly, he should take a non-drowsy anti-histamine like cetirizine (there are lots of alternatives but check they are non-drowsy). If he also suffers from itchy eyes, then sodium cromoglycate eye drops used up to four times a day work like a charm (not for use if he wears contact lenses). All of these are available over the counter from a chemist.

If that combination doesn't work despite taking it all regularly, then grass or birch pollen desensitisation (also called immunotherapy, when increasing amounts of allergen are given under-the-tongue or by injection on a daily or weekly basis) is available in some NHS allergy centres; check out the BSACI website to see a map of allergy clinics and what they offer.

A good argument for persuading people to take hayfever seriously is to tell them that children with hayfever are four times more likely to drop a grade between their winter and summer exams if they have hayfever compared to those who don't, and seven times more likely to drop a grade if they take drowsy-making anti-histamines.

Q. MrsDeVere: My 12-year-old has severe atopic eczema from birth. Now he has horrible hay fever and has just been diagnosed with asthma.  He is autistic so cannot always tell me what is going on. How do I help him? He is really suffering with the pollen allergies and they can set off an asthma attack.

I don't feel I know how to manage it all properly and I need a plan. Can ENT help or are there specialist allergy clinics? Is it worth asking for a referral or is this the sort of thing I should just be able to manage myself? Currently I give him a generic hayfever tablet once a day and he has brown inhalers daily.

A. Dr Paul Seddon: I think you do need advice from someone who knows about allergies. Ask your GP if there is a paediatrician who runs an allergy clinic in your area. Alternatively, if your son is under a paediatrician for his asthma they may be able to help. If there are no paediatric allergy clinics in your immediate area your GP may be able to refer you to one which is further away.

Q. Milica261613: My five-year-old boy has asthma. Allergy tests to inhalant allergens confirmed a ragweed allergy. He takes Flixotide (fluticasone propionate) twice a day. His asthma attacks are rare but difficult and caused by allergens as well as by viruses. I say difficult because he doesn't have a good response to bronchodilators.

Ventoline (salbutamol) helps him, but not exactly as it should, ie initial therapy gives an effect, then the situation is stagnant, and then level of oxygen falls again. Berodual (fenoterol, ipratropium bromide) initially helps, but after 2-3 treatments he starts coughing, irritating, which takes hours and introduces him to a new crisis. I've read about Atrovent (ipratropium bromide) and Xopenex (levalbuterol tartrate), but among the adverse reactions are difficulty breathing, so I am afraid to try them. Could you please tell me if there is any possibility that he has an allergy to any of the ingredients of the aforementioned medicaments? And please recommend for which substances he should be tested in order to find the best bronchodilator for him?

A. Dr Paul Seddon: There are really only two types of bronchodilators:

1. Beta-agonists - this includes Salbutamol, Fenoterol and Levalbuterol

2. Anticholinergics - including Ipratropium

There are really only minor differences between all the beta-agonists on the one hand, and between all the anticholinergics on the other hand. Berodual is a combination inhaler which is not widely used in children - it is really designed for adults. If a child with acute asthma is not responding well to a beta-agonist, or the effect is not sustained, it may be worth adding an anticholinergic, but if the asthma is so acute this would normally be in a hospital emergency department. There is rarely any benefit in switching to a different beta-agonist since they all work in the same way.

If bronchodilators stop working, or are only lasting a short time, what is usually needed is treatment with a steroid - either by mouth (for an acute severe problem) or by inhaler. Is your child under the care of a paediatric respiratory specialist? If not, it would be reasonable to ask for a referral for advice.

Q. Goldthorpewise: Should an allergic cough be treated in the same way as asthma? Could it be more related to post nasal drip and be treated with nasal sprays instead? Would treatment with steroid nasal sprays be more desirable than steroid inhalers, if this were the case? How can it be determined whether a child has allergic cough or asthma?

A. Dr Samantha Walker: Allergic and non-allergic coughs can be difficult to differentiate and so I can't answer your question without asking a lot more questions; you will need to consult your doctor for specific advice. Steroid inhalers and steroid nasal sprays have similar safety and tolerability profiles.

Q. Penfolds5: My question is about desensitisation for hayfever. Do you consider that, so long as it does not trigger dangerous reactions during the process, it is safe? Are there any longer-term disadvantages of desensitisation (e.g., effects on the immune system more generally), or do you have any concerns that there might be? 

A. Dr Samantha Walker: Yes, is the quick answer! Desensitisation for hayfever given to carefully selected people is very effective, and safe as long as it is carried out by trained healthcare professionals in a suitable environment like an allergy clinic. There have been no reported adverse effects of long term use as far as I am aware.

Q. MOsMum2: My 12-year-old has had delayed reactions to baked milk in a muffin - about an hour after eating he developed hives and a cough. We treated with antihistamine and ventolin. Is this still classed as anaphylaxis since it was delayed? Why did it occur an hour after eating the food? He would like to be desensitised to milk, can we still follow the milk ladder by going down several steps and slowly working back up again, and will this help him outgrow his milk allergy?

A. Dr Adam Fox: is an immediate type (involves IgE antibodies) allergy with a respiratory component, which is the definition of anaphylaxis. The delay is due to the effect of mixing the milk in with wheat usually which delays the response. Desensitisation could well be an option but you need to do this under medical supervision.


Symptoms and how allergies work

Q. lmnz: How common and severe can skin contact reactions to foods be? It's proving a real problem with school and integrating with the rest of society.

A. Dr Adam Fox: It is unusual for these to be severe. An American study showed that only 30% of peanut allergy patients have skin contact reactions and none of these were severe. It seems you need to eat the food you are allergic to in order to get a really nasty reaction.

Q. lmnz: Can you have sensitivity to an allergen in one organ (eg skin) without other organs (lungs/digestive system)? Will digestive system sensitivity always be more severe than skin contact? Do we understand why some allergens seem to react to different organs (eg dust/pollen in lungs)?

A. Dr Samantha Walker: You can, although often allergies do manifest themselves in more than one organ systems although not necessarily on exposure to the same allergens. The type of symptoms you'll get largely depends on the route of exposure, so people allergic to peanuts may get mouth and lip swelling (followed by skin rashes if severe) because they're absorbing it through the mouth, whereas people allergic to pollen will get lung/nose problems because they're inhaling it through the nose and lungs. Abdominal allergy symptoms almost never occur on their own, they are preceded by mouth and lip symptoms for the same reason.

Q. lmnz: Is there any research evidence on whether histamine levels in blood/brain can cause behavioural changes?

A. Dr Adam Fox: When kids are starting to have an allergic reaction, as histamine is released, they often show behavioural changes before then getting rashes etc but I suspect your question is really asking whether kids with behavioural problems may have an underlying histamine issue, in which case I am not aware of any evidence to support this.

Q. OliveCane: Could a reaction to a cat allergy be in the form of developing a cough?

A. Dr Samantha Walker: Yes, although not on its own; allergy to cats almost always causes wheezing, chest tightness, sneezing and itchy eyes as well as cough.

Q. OliveCane: My son has multiple delayed allergies, including wheat. Should he be able to tolerate barley? Have any of your patients who react to chicken eggs been able to tolerate quail/duck eggs?

A. Dr Adam Fox: Yes to barley, usually. No to the eggs!



Q. fearofmusic: Can you explain why AllergyUK promoted IgG food intolerance testing for many years? Why did Allergy UK give a consumer award to an IgG testing service? Why has Allergy UK never publicly apologised for this? Why are several of the people who allowed this still involved in Allergy UK?

How many children do you estimate have been malnourished as a result of IgG food intolerance testing promoted by Allergy UK? I understand Dr Fox that this was before your time at AllergyUK and you are to be commended for cleaning it up. But I can't understand why some of the old guard are still there.

A. Dr Adam Fox: Allergy UK does not endorse food intolerance tests and has not done for several years.

Allergy UK is the leading national patient charity supporting the estimated 21 million allergy sufferers in the UK. Our dedicated helpline, support network, website and online forum provide support to over 250,000 people each month, seeking information about allergies.

The charity's primary objective is to support those with allergy but we are commonly contacted about food intolerance. It is worth bearing in mind that there is currently no other organisation that offers any support to those with food intolerance, and we remain the charity that is most commonly approached by such patients. True food allergy is a reaction involving the immune system whereas food intolerance is not so clear cut and there is still limited scientific research.

Although not life threatening, food intolerance can, and often does, make the sufferer feel extremely unwell. It may also have a major impact on ability to work and on enjoyment of social life. Ongoing symptoms can affect the person psychologically as they may feel that they will never get better.

Allergy UK always clearly states that the gold standard, and only reliable way, to find out which foods are causing adverse reactions in an individual is by keeping a detailed food and symptoms diary, alongside a food exclusion diet, ideally under the supervision of a registered dietitian.

Unfortunately there are insufficient numbers of registered dieticians working in the field of food intolerance. Historically the limited evidence available was that IgG testing for food intolerance could be found to be of benefit by patients, who often reported this anecdotally to the charity.*1;2.

It was for this reason, and not a financial one, that the decision was made to work with laboratories offering IgG testing, over a decade ago.

Allergy UK, back then, provided information on companies that carried out IgG testing to those who contacted the organisation about food intolerance. However, we always advised that tests were not scientifically proven and that any evidence was anecdotal.

Understanding of health issues, diagnosis and treatment change over time as new scientific evidence emerges. Over the years Allergy UK has developed a comprehensive health advisory board, with a broad range of NHS specialists. The advisory board's advice is now very clear that these tests do not have a role in diagnosis of food allergy or intolerance. For this reason, Allergy UK's association with IgG testing came to an end a number of years ago.

The trustees of the charity, which include the Chair of the Health Advisory Board have been informed by this view and taken steps to ensure that our position on this is clear.

1. Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. W Atkinson, TA Sheldon, N Shaath, PJ Whorwell in Gut 2004: 53 1459-1464 doi: 10.1136

2. Food allergy in irritable bowel syndrome: new facts and old fallacies. E Isolauri, S Rautava, M Kalliomaki – Gut 2004: 53 1391-1393 10.1136


Last updated: 7 months ago