Desensitisation therapy for allergies in children: part 2

In the second article of a two-part series, Professor Nick Makwana explains more about how desensitisation therapy can be used for allergies in children, including what ways it can be used and side effects of the treatment.

What are the different ways of performing desensitisation?

Subcutaneous immunotherapy (SCIT) involves a series of injections aimed at desensitising the patient. Currently, it's available for both grass and tree pollen allergies. The treatment regimen involves six injections administered over 6 weeks before the onset of pollen season each year, spanning three years. SCIT has demonstrated high effectiveness and is generally well-tolerated by most individuals with severe hay fever. However, rare but severe allergic reactions, particularly in children with asthma, can occur, making this treatment unsuitable for asthmatics. SCIT is exclusively administered under meticulous supervision in a hospital setting, with each injection followed by a 1-hour observation period.

Sublingual immunotherapy (SLIT) consists of placing allergen extract under the tongue via tablets or drops. This method is highly safe, with severe reactions being exceptionally rare; however, the initial dose is always administered under careful medical supervision. Consequently, SLIT is particularly suitable for asthmatics whose condition is well-controlled. The prescribed treatment dose is taken daily for three years and has been proven to exert a lasting influence on the immune system.

Are there any side effects of immunotherapy?

As with all medications, SLIT can potentially cause side effects, and in the early stages of the treatment it is common to experience the following within a few minutes of taking the dose:

• Mouth itching
• Irritating sensation

Typically, this resolves within 20 minutes of beginning treatment but can be eased with readily available over-the-counter antihistamines.

Other side effects which may affect up to 1 in 10 people are noted below.  These tend to occur in the first week of taking the medication and generally mild to moderate and short lived:

• Eye or ear itching
• Numbness of skin, mouth or tongue
• Asthma symptoms
• Eye, nose or mouth inflammation
• Cough or sneeze
• Shortness of breath
• Nasal discomfort
• Dry throat
• Swelling of lips or tongue
• Stuffy or runny nose
• Mouth blisters
• Stomach pain or discomfort
• Heartburn
• Tiredness
• Itching
• Chest discomfort
• Fever

How successful is immunotherapy (desensitisation)?

The patients I have treated with immunotherapy report an improvement in symptoms and less use of traditional treatments, such as antihistamines and steroid nasal sprays.  As also mentioned, using immunotherapy from an early age may prevent new allergies developing and reduce the likelihood of getting asthma, which we know is 8 times more likely in child who suffer from hay fever.

Food Immunotherapy / Desensitisation

Desensitsation, also referred to as immunotherapy, involves administering gradually increasing doses of an allergen extract to alleviate or diminish the symptoms associated with the condition it triggers, such as hay fever or specific food allergies. Initially conducted approximately a century ago for pollen allergies, it is now globally recognised as a safe and efficacious treatment for allergies. While extensively used for hay fever, pet allergies, and house dust mite allergies, it is now also offered for select food allergens, with the aim of enhancing the quality of life for children and their families.

What is food immunotherapy?

Oral tolerance induction (OIT), alternatively known as oral desensitisation therapy (OD), entails administering minute yet progressively increasing quantities of food to which the child is allergic. The objective is to heighten the tolerance level towards the food, enabling the consumption of larger amounts without triggering symptoms. Consequently, accidental exposure to small quantities should not provoke reactions. This therapeutic approach has primarily been researched with milk, egg, and peanut allergies. Notably, Palforzia®, a peanut-containing capsule, has recently emerged as the first licensed food immunotherapy treatment. While our NHS service has long provided milk and egg desensitisation, we now extend the option of private treatment, inclusive of Palforzia®.

How does food immunotherapy work?

There has been an increasing body of research which has been looking at how the treatment impacts on the immune system.  It has shown that the regular exposure to the food causing allergy, but at a level below that which causes a reaction, leads to the production of an antibody called IgG4.  This antibody has a blocking effect on IgE antibody, which is the antibody that is responsible for causing allergic reactions. 

Which food allergies can be treated with immunotherapy?

Most research has been done on desensitisation to milk, egg and peanut.  As noted, we have been offering desensitisation to milk and egg on the NHS for some time but can also offer desensitisation to peanut using Palforzia®.

How long does the process for food immunotherapy take?

This will depend on which food immunotherapy is being given and which protocols are used.  Some are faster than others, but a typical protocol takes 8-12 weeks, although Palforzia®’s protocol takes 6 months to reach the top dose. The doses are increased with specific gaps between doses but reactions or other factors such as incidental illness or missed doses may require a longer gap between doses. Once we have reached the top dose (maintenance) then the patient needs to continue to take this regularly to maintain effect.  The frequency of this dosing can be reduced, but not stopped, over time without apparent loss of effect.

Is food immunotherapy the right treatment for my child?

Although a child may be suitable for immunotherapy, it may still not be the right treatment option for them.  For many patients, continuing to avoid the food they are allergic to, coupled with an appropriate emergency action plan is still the most appropriate way to manage the allergy. Food immunotherapy is associated with a risk of reaction and can impact on day-to-day life during up dosing and beyond. 

To decide if immunotherapy is right for your child there is an important process of shared decision making, which together with detailed information about the treatment, will help doctors to decide if it is the right thing to do. Your child will only be considered for treatment once this process has been completed and you will be required to sign a consent form to confirm that you understand the risks and benefits of each approach.

If you would like to book a consultation with Professor Nick Makwana, simply visit his Top Doctors profile today