Food allergy is common, affecting 5% of UK children and can cause severe allergic reactions. Every year, children have accidental exposures to the foods they are allergic to and whilst most reactions are mild, occasionally, they can be more severe. Until recently, the only treatment for food allergy has been careful avoidance. This is starting to change and there has now been over 20 years of intensive medical research into desensitisation to common food allergens, such as peanut, milk and egg, which means that in some cases, there may be other approaches to treatment.

Allergy London offers desensitisation to a range of food allergens for younger children including peanut, treenuts, sesame, wheat, milk and egg. We work closely with our partner practice, the Allergy Centre of Excellence, to offer an even broader range of desensitisation for children up to 17 years of age including those who have a history of severe anaphylaxis. The Allergy Centre of Excellence is a joint service founded by 3 paediatric allergy Professors, offering desensitisation and high-risk diagnostic testing at Great Ormond Street Hospital as well as centres in Marylebone and Poole, Hampshire.

Further details can be found here:

What is food desensitisation?

Oral Desensitisation (OD), also known as Oral Tolerance Induction (OTI or most commonly as OIT) or food desensitisation, is a treatment that involves giving very small, but gradually increasing amount of the food that the child is allergic to. The intention of this is to increase the tolerance to the food allergen so that larger amounts of it can be taken without causing any symptoms and as a result, allergen containing foods can be eaten safely or at very least, accidental exposures to small amounts of them will not cause reactions.

This treatment has been most studied for peanut, milk and egg. It is important to recognise that this treatment leads to a state of desensitisation (a temporary state, where greater amounts of allergen can be tolerated without symptoms) and not necessarily true ‘tolerance’ (a permanent state where any amount of the allergen can be consumed without any risk of reaction). In practice, this means that the regular doses of allergen must be continued regularly in the long term for the treatment effect to remain.

This treatment is thus not a cure and if doses of the allergen are not continued regularly, the risk of reaction returns.

Watch our videos about food desensitisation

What does food desensitisation involve?

The starting point is an assessment visit, to discuss the process and ensure that you fully understand it. The assessment will involve a detailed history and examination focussing on the relevant food allergy and may require skin prick or blood tests if these have not been done for more than 6-12 months. It will also require a detailed asthma assessment and where appropriate, lung function testing as any child whose asthma is not extremely well controlled, would not be suitable for treatment.

If it is felt your child is suitable for the treatment, you will be asked to sign a consent form to indicate that you have fully understood the risks involved. You will be prescribed an Epipen and trained in its use, if this hasn’t been done already. In the case of milk or egg allergy, if your child has never been exposed to baked milk or baked egg, it may be necessary to clarify if your child is able to tolerate this, by consuming a fairy cake under supervision. If they can, this suggests a different strategy for desensitisation may be used but if your child cannot tolerate milk/egg in the baked form, and is otherwise suitable, then the treatment can proceed.

Treatment starts with a tiny amount of allergen being given under medical supervision. You will be shown how to make up the correct doses in order for the same dose to be given safely at home. Depending on the allergen and the protocol, you will then either slowly increase the dose at home or, for example with peanut, just give the same dose, returning intermittently to give an increased dose under direct medical supervision. You will be supported, with close email contact throughout the process.

How long does the food desensitisation process take?

This will depend on the protocol use and the success of the treatment. With peanut, sesame or treenuts it may take approximately 4-6 months to get to the ‘maintenance’ dose but it is important to note that this can be slowed down, with ‘up dosing’ visits where higher doses are carefully trialled, may be done at longer intervals if preferred. If a child has a lot of reactions, this may also slow the process down. The important thing is that safety is more important than how quickly the process is done.

How does Food Desensitisation work?

Studies on desensitisation suggest that exposure to the allergic at doses that do not cause reactions, promotes the production of food specific IgG4 antibodies and reduces food specific IgE. This gradually tips the balance towards tolerance rather than allergy, at least while the levels are maintained.

What allergies does Food Desensitisation work for?

Sesame, treenuts, peanut and milk are the allergens most commonly desensitised. However, there is increasing interest in treatment for allergens such as pea, lentil, chickpea and others becoming available.

Does Food Desensitisation have any side effects?

The key symptoms are those of allergic reactions to the doses given – these are usually mild (itch, rash, hives as well as gastrointestinal symptoms such as abdominal pain). More severe reactions are rare but can happy including anaphylaxis. The risk of this will vary according to the allergen and the child’s age. Studies relating to 1127 patients receiving Palforzia (peanut) in children age 4 to 17, 14 patients (1.2%) had a severe reaction, all of which responded to emergency treatment with Epipen. Safety is a key issue to be discussed before starting treatment.

How effective is food desensitisation?

There are numerous studies from around the world as well as systematic reviews (where the results of lots of studies are combined) that demonstrate that OIT works well for peanut, milk and egg. Different studies use different approaches, in different children but report up to 100% effectiveness. In practice, most children (over 90%) will achieve maintenance dosing with the remaining 10% dropping out due to a mixture of logistical or medical reasons. Multiple studies have also shown a clear improvement in quality of life for both children and parents, where OIT has been performed.

How safe is food desensitisation?

There has been a lot of concern around safety of this treatment, because of the known risk of severe allergic reactions that could happen to foods. Most, if not all children, will have some allergic reactions during the treatment but these are virtually all mild. Typical reactions are rashes, lip/face swelling, wheeze and abdominal discomfort. Severe reactions, requiring adrenaline are reported in a small number of patients in the published studies but with this treatment now widespread in Europe and the US, it is very reassuring that there have been no reported fatal or near fatal reactions reported. However, there are a number of clear ways that the risk of severe reactions can be reduced and many lessons have been learned for the severe reactions that have occurred. As a result, most reactions we see happen when there is a deviation from the rules around dosing (such as avoiding the dose when the child is unwell).. It is impossible to desensitise without any risk of allergic reaction, but this is further mitigated by not offering it to certain patients, ensuring parents are fully able to manage allergic reactions in the unlikely event that they happen (every patient will be prescribed and trained how and when to use Epipens), and observing some simple rules around dosing.  The risk of reacting must also be considered in the context of the risk of severe reactions that may happen if the child were not desensitised and had an accidental exposure.

There is also a concern that OIT can result in the development of eosinophilic oesophagitis (EoE – an inflammatory condition of the oesophagus) and other food-induced gut related problems. A systematic review reported EoE in up to 2.7% of patients undergoing OIT for IgE mediated food allergy (although the review is based on incomplete datasets, because most trials of OIT have not reported the presence or absence of EoE as a longer-term adverse event) although as EoE is known to disproportionately affect children with allergies anyway, there is no evidence as yet of a causative link. Importantly, EoE tends to settle if OIT doses are reduced.

Currently, international guidelines, both European and North American, on the management of food allergy support the role of OIT offered by allergy specialists, reflecting our improved understanding and the experience of the many doctors in these areas now offering this. Palforzia, became the first licenced food OIT in the UK in 2021 and received NICE approval for NHS use in 2022.

What if food desensitisation doesn’t work?

This treatment does not work for everybody, but if the dose cannot be increased above a certain point because of recurrent side effects, then this dose can be continued for 3 months and then increasing attempted again. This can often be successful. Even if only limited desensitisation is achieved, this can still protect from reactions due to accidental exposures. It is also possible for smaller doses, if required daily for a long period, to be changed to an easier alternative eg chocolate button in milk OIT. There are also additional options available now such as Xolair (Omalizumab) which reduces reactivity to food allergens and can be used alongside OIT when side effects are very troublesome as well as emerging options such as sublingual immunotherapy.

Can I get food desensitisation for my child?

OIT is not right for everyone. If your child has poorly controlled asthma or is very averse to eating even small amounts of the food, then they may not be suitable. The size of the allergy tests or severity of previous reactions are seldom a reason not to offer treatment.

If your absolute priority in managing your child’s food allergy is avoiding any reactions, then a policy of strict avoidance is probably best. If you are prepared to accept a regular daily treatment, with occasional mild allergic reactions then OIT is worth considering.

How much does food desensitisation cost privately?

Cost of treatment will depend on the cost of the allergen itself and how many treatments are being done concurrently as this can be upto 3 allergens together. It will also depend on the number of visits to increase the dose so will depend on the protocol used. Peanut desensitisation using Palforzia will be more expensive as we are required to use the proprietary capsules from Aimmune.

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Food OIT (desensitisation) carries significant risk of allergic reaction, especially when the dose is increased and this should NEVER be attempted without careful medical supervision. Please do not consider attempting to desensitise your child yourself, even if you have access to detailed protocols. It is dangerous to do so and puts your child at risk of harm.

Written by

Professor Adam Fox

Date reviewed: March 2021

Adam Fox is a Professor of Paediatric Allergy with over 20 years experience in both the NHS and private sector. Professor Fox is Commercial Medical Director at Guy’s & St Thomas’ Hospitals NHS Foundation Trust and Professor of Paediatric Allergy at King’s College London and the founding Director of the KCL Allergy Academy, a postgraduate educational programme, which was a finalist at the BMJ Awards in 2018.

View Professor Fox’s profiles on:

Food Desensitisation

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