Patient information leaflets

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FOOD ALLERGY TESTING

This information leaflet explains what to expect when you have food allergy testing at St. Bartholomew’s Hospital. If you have any questions or concerns, please do not hesitate to contact us –details are at the end of this information sheet

What is a food challenge?

A food challenge is when a food we suspect you may have an allergy to, is given to you under close medical supervision. This involves eating increasing amounts of the suspected food, until a typical portion is eaten, or a reaction occurs.

What are the benefits of having a food challenge?

A food challenge will confirm whether or not you have a food allergy.

If the test is negative this may help you and your family have a less restricted diet, without fear of you reacting to a certain food.

If the test is positive, our allergy dietitian will advise you on how to safely exclude the food from your diet. You will also be given advice on what to do in the event of accidental exposure and you will be able to pass this information on to your doctors, family members and anyone else concerned.

Are there any risks associated with having a food challenge?

There is a risk that you will have a reaction to the challenge food. This is why the challenge testing is done in a hospital setting, where an allergy nurse specialist will monitor you for any signs of allergic reaction and a doctor will always be available if needed.

If you do have an allergic reaction the food challenge will be stopped. Medicine will be given to relieve the symptoms and to stop the reaction from getting worse. This may be an antihistamine, steroid or in a severe reaction an adrenaline injection may be given.

What is a prick-prick skin test?

This is often done before the oral food challenge as the first step. You will have a skin prick test with the food you are requested to bring in (this is usually called a “prick-prick skin test”). Please bring the test food(s), without any flavouring’s or spices, in individual containers to prevent cross contamination.

A lancet is used to prick the food and the same lancet is then used to prick your skin. After 15 minutes, the site is inspected. A positive reaction is when the skin around the needle prick becomes itchy, red and develops a swelling which usually disappears within 30-60 minutes. If the skin prick test is negative, you may go on to have an oral food challenge. If the skin prick test is positive, the test will stop here.

In some cases, the prick to prick skin test may be done during your clinic appointment with the allergy dietitian, prior to your oral food challenge appointment.

What happens during the challenge?

Please arrive on time or your test may have to be postponed.

On arrival you will be seen by the allergy nurse specialist who will take your pulse, blood pressure and peak flow. These will continue to be monitored throughout the day

The challenge procedure will be explained to you, including the risks and benefits and you will be asked to sign a consent form.

In some cases, a small cannula (plastic tube) may be inserted in your arm before the challenge begins. This will be decided by the challenge team, depending on your medical history.

You will be given increasing portions (doses) of the challenge food, in 15–30-minute intervals. The challenge team will check for signs of an allergic reaction between doses. Reactions tend to be mild and

include: itching, rash swelling, vomiting, diarrhoea. Sometimes people experience more severe reactions including: throat tightness, difficulty breathing, light-headedness/dizziness. A doctor is present during the testing to treat you if needed. 

You will need to stay for observations for approximately 1 hour after the final dose of food is given, to make sure there is no delayed reaction.

If you have an allergic reaction at any point, the challenge will be stopped immediately. You will be treated accordingly and reviewed by a doctor, If you experience mild symptoms, we may decide to repeat the dose. If the symptom subsides, we may continue with the challenge.

If you are unwell on the day please contact us as soon as possible and we will reschedule.

What food will be required?

You will need to bring along the foods for prick-prick skin testing and oral food challenge. You will be advised which foods to bring at the time of booking. Please ensure the foods are in the relevant form, as outlined below:

* No seasoning, spices, sauces, oil etc

What happens after the challenge?

A positive challenge:  

• This is when you react to the food given. We will observe you for a few hours after a reaction and occasionally, you may need to be monitored longer or even in hospital overnight.
• A positive reaction means you are allergic to the test food
• You need to avoid that food and you will be reviewed by our allergy dietitian.
• We will also give you written information about managing your allergy.

A negative challenge test:

• This is when no allergic reaction occurs to the test food.
• A negative test after eating a typical portion means you are not allergic to the food and we will discuss how to re-introduce it into your diet. If you are unable to eat a typical portion, our allergy dietitian will advise you on what to do next.

Reactions after you are discharged

• We will give you written information on delayed reactions and advise on what to look out for and how to treat it, before you leave the hospital.
•  Please contact our Specialist Allergy Nurses on 07720 948 385 if you develop a delayed reaction.

Your GP will be sent a letter with the challenge result

Are there any alternatives?

A food challenge is the only safe and definitive way to find out whether you have a food allergy or not. However, you may choose not to have a food challenge and continue to avoid the food you might be allergic to.

Further information

If you have any questions or concerns, please contact the Allergy Nurse Specialists (Monday to Friday 9am-5am) on Tel: 020 3765 8096 or 07720 948 385 or email: adultallergynurses@nhs.net

For appointment booking queries please contact our

Patient Pathway Co-ordinator on 0203 765 8584 or

Email: adultallergy.bartshealth@nhs.net  

Large print and other languages
This information can be made available in alternative formats, such as easy read or large print, and may be available in alternative languages, upon request. For more information, speak to your clinical team.
 

এই তথ্যগুলো সহজে পড়া যায় অথবা বৃহৎ প্রিন্টের মত বিকল্প ফরম্যাটে পাওয়া যাবে, এবং অনুরোধে অন্য ভাষায়ও পাওয়া যেতে পারে। আরো তথ্যের জন্য আপনার ক্লিনিক্যাল টিমের সাথে কথা বলুন।

Na żądanie te informacje mogą zostać udostępnione w innych formatach, takich jak zapis większą czcionką lub łatwą do czytania, a także w innych językach. Aby uzyskać więcej informacji, porozmawiaj ze swoim zespołem specjalistów.

Macluumaadkaan waxaa loo heli karaa qaab kale, sida ugu akhrinta ugu fudud, ama far waa weyn, waxana laga yabaa in lagu heli luuqaado Kale, haddii la codsado. Wixii macluumaad dheeraad ah, kala hadal kooxda xarunta caafimaadka.

Bu bilgi, kolay okunurluk veya büyük baskılar gibi alternatif biçimlerde sunulabilir, ve talep üzerine Alternatif Dillerde sunulabilir. Daha fazla bilgi için klinik ekibinizle irtibata geçin.

یہ معلومات متبادل فارمیٹس میں دستیاب کی جا سکتی ہیں، جیسا کہ پڑھنے میں آسان یا بڑا پرنٹ  اور درخواست پر متبادل زبانوں میں بھی دستیاب ہو سکتی ہیں۔ مزید معلومات کے لیے، اپنی کلینکل ٹیم سے بات کریں'۔

Patient Advice and Liaison Service (PALS)

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Reference: BH/PIN/1123

Publication date: March 2022

All our patient information leaflets are reviewed every three years.

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