Dr. Adam Fox answers common questions parents would like to know when their child is first diagnosed.
Dr. Adam Fox
– Consultant Paediatric Allergist, Guy’s & St. Thomas’ Hospital, London (MA(Hons),MD,MSc,MB,BS,DCH,FRCPCH,FHEA,Dip. Allergy)
- Q: What should a parent do if they suspect their child has a food allergy?
- The first step should always be to visit your GP and discuss your concerns with them. Often, parents report that they don’t feel they have had these concerns taken seriously, but in 2011 the National Institute for Clinical and Healthcare Excellence (NICE) produced guidelines for GPs to ensure that they took concerns about food allergy seriously. It also provided them with guidance about which questions to ask and which tests to consider. NICE have produced an excellent parents guide that explains exactly what the GP should be doing when you raise concerns about food allergy.
- Q: If a large 'weal' appears from a skin prick test, does this mean your child is highly allergic to that particular food?
- No. Skin prick tests (and allergy blood tests) detect allergic antibody produced by the immune system. The more that they detect, the more likely it is that you have a genuine allergy to that thing. In effect this means that if you have a large ‘weal’ on a skin prick test, or a large positive blood test, then you can be more confident that there is a real allergy. Allergy tests can not predict severity of likely reactions – this is because severity is determined by many other unpredictable factors, e.g. your state of health when you react (being unwell predisposes to more severe reactions), the amount of food eaten and the form it is in e.g. roasted peanuts are more likely to cause a bad reaction than boiled peanuts. Exercise can also worsen a reaction.
- Q: Do allergic reactions increase in severity as the child gets older?
- There is an urban myth that each time you react, it gets worse. Allergic reactions are unpredictable and the severity of any reaction is influenced by many factors. These include your state of health when you react (being unwell predisposes to more severe reactions), the amount of the food eaten and the form it is in e.g. roasted peanuts are more likely to cause a bad reaction that boiled peanuts. Exercise can also worsen a reaction. The main risk factors for a severe reaction are: presence of asthma, a history of severe reactions, being a teenager and allergy to nuts.
- Q: If a baby has been diagnosed with a milk allergy, are they likely to develop other food allergies?
- About 30% of children with milk allergy will have other food allergies so it’s worth having this checked out. Having food allergy also predisposes to other allergic problems such as eczema, asthma and hay fever. For example about 75% of children allergic to nuts, will develop asthma.
- Q: When a child has been diagnosed with a nut allergy does this mean they should avoid all nuts including peanuts (part of the legume family), water chestnuts (aquatic vegetable), coconuts, pine nuts and nutmeg (seeds)?
- This depends on the individual circumstances but ideally, it is worth getting a precise diagnosis as to exactly which nuts are a problem. Nutmeg, coconut, chestnut and butternut are very rarely a problem and are not routinely screened for in nut allergic children. Pine nuts are actually seeds, so again are not routinely checked for. However, 30-40% of peanut allergic children are allergic to a tree nut and 25% allergic to sesame, so if a nut allergy is diagnosed, make sure there is consideration given to these when testing is done.
- Q: How, and when, should you test if your child has outgrown an allergy?
- Some allergies are commonly outgrown – e.g. milk, egg, wheat, soy – often during childhood, so regular annual retesting is recommended. Nut, fish and shellfish allergy is less commonly outgrown and thus testing may be less frequent. But regular follow-up with an allergy doctor is still recommended to check for other allergic problems, and to go through avoidance advice and emergency treatment.
- Q: The MMR injection contains egg protein. Is this safe for a child with an egg allergy to have?
- The MMR is safe in children with egg allergy and no extra precautions are needed so it can be done at the GP surgery. There was concern about the MMR vaccine in egg allergic children as the vaccine is grown on chick cells. However, it has become clear over time that the amount of egg is not enough to cause a reaction in even the most sensitive egg allergic child.
Allergic reactions to the MMR are very rare and are most commonly caused by reactions to other components of the vaccine such as gelatine or neomycin. The most important reason to take extra precautions with the MMR vaccine is if there has been a previous reaction to it. As there was previous advice (withdrawn in 2007) suggesting extra care should be taken with egg allergic children receiving the MMR, some doctors and nurses may recommend the vaccine is given in a children’s ward, but this is not necessary.
- February 2013