Milk allergy is common, affecting 2-3% of UK children and can cause severe allergic reactions and every year, around 40% of milk allergic children have accidental exposures to milk. Milk allergy is often outgrown during early childhood, but in some children can persist in later teenage years or even early adulthood. Until recently, the standard treatment has been careful avoidance but this is starting to change and there has now been a 15 year history of medical research into desensitisation to milk.
What is Oral Desensitisation?
Oral desensitisation (OD), also known as Oral Tolerance Induction (OTI or 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 OD is to increase the tolerance to milk so that larger amounts of milk can be taken without causing any symptoms and as a result, milk containing foods can be eaten safely or at very least, accidental exposures to small amounts of milk will not cause reactions. This treatment has been most studied for milk and egg and is also the subject of intensive research for peanut allergy. It is important to recognise that this treatment leads to a state of desensitisation (a temporary state, where greater amounts of milk can be tolerated without symptoms) and not necessarily true ‘tolerance’ (a permanent state where any amount of milk can be consumed without any risk of reaction). In practice, this means that the regular doses of milk must be continued regularly in the long term for the treatment effect to remain. If it isn’t, the risk of reaction returns.
How effective is it?
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 oral desensitisation works well for milk and egg. Different studies use different approaches in different children but report up to 100% effectiveness.
Children tend to have 3 possible responses to treatment:
- They achieve a full, high dose that they can tolerate without any problem
- They can’t reach the full dose without persistent side effects but can still tolerate a useful amount of milk without reactions
- They are unable to progress at all due to side effects
One protocol, based on a German one (Staden et al 2007), was adapted by the Paediatric Allergy team in Leicester Children’s Hospital. They published a report on the first 50 patients they have treated, with 64% of patients achieving regular doses of up to 250mls of milk consumed per day. They have since reported that 75% of their patients achieved the full 250ml dose, with a further 15% achieving a significant increase in their milk tolerance, albeit not the full, top dose. Only 10% were unable to progress at all. Studies are starting to show that children with very high skin prick or blood allergy tests to milk are less likely to find the treatment to be effective and this will be considered at any assessment. Multiple studies have also shown a clear improvement in quality of life for both children and parents, where oral desensitisation has been performed.
How safe is it?
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 oral desensitisation 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. The most important influence on safety is the actual desensitisation protocol. Some studies are focussed on a rapid dose increase, with multiple hospital visits. This can mean the treatment works much more quickly but carries a greater risk of severe reactions. For me, any preferred protocol, will have been used widely for a long time, and be slower, with much smaller dose increases, but have the benefit of less hospital visits and be much safer, but has the disadvantage of being slower. We should prioritise safety first. 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 (patient will be prescribed and trained 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 oral desensitisation can result in the development of eosinophilic oesophagitis (E0E – 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 oral desensitisation for IgE mediated food allergy (although the review is based on incomplete datasets, because most trials of OD 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.
Currently, international guidelines on the management of food allergy (published in 2014) have stated that oral desensitisation is not well enough understood in terms of safety or effectiveness to be offered as a treatment. However, this is now changing and the upcoming European Academy of Allergy & Clinical Immunology guideline for allergen immunotherapy has now stated for the first time that this treatment can be offered by allergy specialists, reflecting our improved understanding and the experience of the many doctors in Europe now offering this.
Is this treatment the right thing for my child?
Oral desensitisation is not right for everyone. If your child has suffered severe reactions, especially to very small exposures to milk or has poorly controlled asthma or other illnesses, then this treatment is not suitable. If your child’s allergy tests are very high (eg skin test >9mm or IgE >50) then this increases the change of problematic side effects and reduces the chance that the treatment will be successful. If you are unable to commit to very reliable daily dosing then this would not be suitable.
If your absolute priority in managing your child’s milk 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 thenoral desensitisation is worth considering.
The most useful scientific articles to read would be the 2 systematic reviews of milk oral desensitisation and the paper describing the Leicester experience of this treatment:
Brozek JL et al. Oral immunotherapy for IgE-mediated cow’s milk allergy: a systematic review and meta-analysis. Clinical & Experimental Allergy. 2012 Mar;42(3):363-74.
Calatayud CM et al. Journal of Investigative Allergology & Clinical Immunology 2014;24(5): 298-307.
Luyt D et al. Implementing specific oral tolerance induction to milk into routine clinical practice: experience from first 50 patients. Journal of Asthma & Allergy 2014;7:1-9.