What happens at a food allergy oral food challenge?

An oral food challenge is the “gold standard” for food allergy testing. Actually eating some of a food you are thought to be allergic to is obviously going to give a definitive answer, which isn’t always the case with other types of allergy testing. We have been through multiple food allergy oral food challenges over the years, both good and bad. Here are some important things to know and some real life experiences of the highs and lows of oral food challenges.

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What is an oral food challenge?

A food allergy challenge is form of allergy testing. The patient eats small amounts of a suspected food allergen, which is gradually increased at regular intervals. This challenge is done under medical supervision see whether the food causes an allergic reaction or not.

If there is an allergic reaction of any sort, the challenge will be stopped and the patient’s allergy symptoms treated. If the challenge is completed with no symptoms of an allergic reaction, the patient is required to stay for observation. This is in case of a delayed reaction. The supervising allergy staff will then given instructions about follow up and eating the food in the future.

In our experience, our allergist has recommended food challenges after skin prick testing (and sometimes IgE blood tests) show a likely allergy, but we haven’t experienced a reaction. This has usually been for foods that our child has never actually eaten before. Sometimes a food challenge is recommended because repeat allergy test results are better and the allergy may have resolved. For example, a child might do a challenge to see whether they have outgrown a milk or egg allergy.

Can food challenges be done at home?

Food allergy oral food challenges are done either in hospital or in your allergist’s office, under medical supervision. There is a very good reason for this. If you have, or your child has, an allergic reaction during an oral food challenge, it is important to have immediate medical care available.

But I’ve heard of other people doing food challenges at home?

You might have heard about people doing in home food challenges. I would never attempt an oral food challenge at home under normal circumstances. That said, we have actually done 2 low risk challenges at home now. But we only did these at home oral food challenges on medical advice from our allergist and in very specific circumstances.

For one challenge, the food had been eaten previously but was only suspected of causing eczema exacerbation and not any more serious allergy symptoms. A skin prick test was only borderline positive. We eliminated this food for a number of months to see whether it had any direct effect on our child’s eczema. We then reintroduced it by doing a measured challenge at home and monitoring for any reaction very closely. Our allergist considered that there was a very minimal risk of an allergic reaction from this process. We of course had detailed instructions on how to do the challenge. And we had an anaphylaxis action plan and medications including EpiPens available just in case.

For the second challenge, our allergist again considered this a very low risk in our particular circumstances. This included improved results of repeat allergy tests and the fact that our child had previously eaten the food without any symptoms of an allergic reaction, but had just not been eating it consistently enough. In these circumstances, our treating specialist recommended a controlled home food challenge. We received very strict instructions on how to do the challenge and again had an anaphylaxis action plan and EpiPens available just in case. Importantly, we had the confidence to manage any reactions and were close to medical care if needed.

Medical supervision required

All of the other oral food challenges we have done have taken place as an admitted patient in the medical day unit of our local tertiary hospital. These challenges took place under the care of trained allergy nurses and under supervision of an allergist. And some of these food challenges resulted in significant allergic reactions, including anaphylaxis.

Never attempt a home challenge unless your own treating allergy specialist has advised that it is appropriate for your particular circumstances and given you very clear instructions. Your allergist will take into account your own circumstances in deciding where to do a challenge. This might include the type of food, past or expected reactions and whether you have asthma or other conditions that might increase the risk of reacting during a challenge.

From personal experience, in the event of an allergic reaction, you’ll be very glad you have immediate medical care at hand.

What happens during an oral food challenge?

Our experience may be slightly different to what happens at your allergy clinic, but the general principles will be similar.

On arrival, the allergy nurse takes observations including temperature, heart rate and blood pressure. The allergist then explains what will happen during the food challenge, the risk of allergic reaction and what to expect if that happens.

Once it is time to start the challenge, it is time to eat the food. This can be quite confronting, especially if it is a food that you have been strictly avoiding for a long time. I remember the conflict I felt watching my small child taste peanut butter for the first time ever. At our challenges, food is normally eaten from a spoon. This is to make sure that the allergen food is not accidentally transferred from hands to face.

Your allergy clinic or treating specialist will have a strict protocol setting out the amount of food for each each ‘dose’ and the time between doses.

What might happen during the challenge

Using our latest challenge as an example – almonds – the first dose was 1/4 almond. We then waited for 15 minutes for observation. The next doses, also given 15 minutes apart, were half an almond, then a whole almond, 3 almonds and finally 5 whole almonds. During this time, the allergy nurse continued to monitor closely and taking blood pressure and heart rate measurements. We then waited for a further 2 hours for observation to make sure there was no delayed reaction. This challenge showed that there was no allergy to almonds.

We also have completed numerous other challenges which did prove a food allergy. We had to stop a peanut challenge after the very first dose due to an immediate reaction (facial swelling, hives and vomiting). The hospital staff immediately gave antihistamines and we stayed for observation. Fortunately this reaction did not progress to breathing difficulties. Our milk challenge was different again, as we made it through each increasing amount of milk to the end of the challenge without any signs of a reaction at all. The challenge was considered a “pass” and we were discussing how to introduce milk into the diet on a regular basis when the reaction occurred. This reaction including flushing, facial swelling, full body hives, vomiting and breathing difficulties (anaphylaxis) and required more medications to treat and a longer period of observation.

Although reactions were frightening at the time, we were in very safe hands at at the hospital.

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What happens after the test?

If you or your child have an allergic reaction during the challenge, the allergy is confirmed. This means that you will have to keep avoiding the food in question. It may be that you are able to repeat allergy testing in the future and try again, depending on your allergist’s advice.

When the challenge is completed without any symptoms of an allergic reaction, your allergist will give you detailed instructions on what to do next. For us, we had to wait a full 24 hours before eating any of the food again. During this time it is important to watch for any delayed reaction. After 24 hours, we had to reintroduce a serve of the food at home. If this was also successful, we had to make sure to eat the food in question around 3 times a week for the next 3 months. After that it needed to be eaten regularly as part of our normal diet.

It is very important to follow advice about eating the challenged food regularly. If not, it is possible to become lose tolerance to that food and risk having an allergic reaction to it in the future.

Practical tips for your oral food challenge appointment

Your treating allergist should give you detailed information about preparing for your food allergy challenge. Make sure you read any information carefully and take notes of anything important. You may need to stop certain medication prior to the challenge. You might also have to supply the food to be challenged, depending on your allergist’s practice. Sometimes you might need to bring a favourite soft food that your child will eat to mix with the challenge food so that they will eat it.

Reassuring children

If you are taking your child for an oral food challenge, depending on age it is good to talk to them beforehand about what is going to happen. They (and you) may be very anxious about trying a food that they have been told could make them sick. It can be reassuring to talk about how the challenge will start with just a small taste and that the doctors and nurses are there to make sure they will be fine.

Antihistamines and other medications

One instruction to check closely is if and when you need to stop medications leading up to the challenge. We had to stop all antihistamines (and other medicines containing antihistamine) at least 72 hours beforehand. Some allergists require longer than this. Antihistamines can mask some symptoms of an allergic reaction. We’ve had to reschedule an appointment in the past due to taking antihistamines too close to a scheduled food challenge.

We take our EpiPens, antihistamines and asthma medications everywhere. Make sure you take them to your food challenge too. Even if you are in a hospital environment, you should have your medication available. This is especially important if there is a chance of a delayed reaction after you leave.

Take something to do

Oral food challenges can take a long time. Between initial observations before you start, the staggered doses and the need to stay for observation afterwards, it can take around 4 hours or more. In the unfortunate event that you or your child have an allergic reaction, the stay could be longer. For younger children, you can take some toys, books, colouring or a favourite movie on an iPad. Teens may be happiest with their phone/iPad or a book. We are fortunate that our children’s hospital has a play therapist who makes sure that everyone has an activity to keep them entertained.

Take a change of clothes

This piece of advice comes from personal experience. Take a change of clothes for the patient. Also consider packing a change of clothes yourself if you are taking your child. During one of our unsuccessful challenges, our then almost 2 year old vomited profusely, all over himself and all over me. While I was able to give my toddler a bath and a change of clothes, I wasn’t so lucky. I had to wait until we got home many hours later to change!

References and more information about oral food challenges

We’ve referred to our personal experiences with oral food challenges in this post. However you should always discuss any questions about your own allergies and allergy testing with your treating allergist/immunologist. For more information about food allergy challenges, we recommend the following references we’ve referred to in this post:

You might also like to read more about different types of food allergy testing which might lead up to an oral food challenge – All about genuine allergy testing – the tests specialists use.

*Disclaimer: Allergy Spot does not provide medical advice. You should always consult a suitably qualified medical practitioner in respect of your own medical conditions, symptoms or concerns. See our Website Terms for more details.

This Post Has One Comment

  1. I never thought that there is such oral food test to determine allergies! At least know, i have some insights!
    I do have some allergies with food rich in protein!

    Will be sharing this with my friends..

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