Food provocations and challenges

An oral food challenge (OFC) is a medical procedure in which a food is eaten slowly, in gradually increasing amounts, under medical supervision, to diagnose or rule out a true food allergy. Please call the Centre to discuss pricing

Overview

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What is a food provocation or challenge?

An oral food challenge (OFC) is a medical procedure in which a food is eaten slowly, in gradually increasing amounts, under medical supervision, to diagnose or rule out a true food allergy. It is usually done when a medical history and allergy tests (skin/blood tests) are inconclusive. Most OFCs are performed openly, meaning that both the patient and doctor know what food is being eaten. In blinded challenges, either the patient (single-blind), or both the patient and the doctor (double blind) do not know whether the real test food is being eaten or a placebo.

What do I need to do ahead of the test?

You need to be in good health on the day of the test. Chronic allergic conditions such as asthma, atopic dermatitis/eczema and hay fever have to be well controlled so they do not interfere with the interpretation of any symptoms. Antihistamines have to be stopped 3 days before the OFC since they might mask mild early symptoms. Intranasal steroids and antihistamines, antihistamine eye drops, leukotriene antagonist or inhaled corticosteroids for asthma do not need to be stopped.

What happens on the day of the test?

The OFC starts with a small serving of the food and after a period of time, usually 15-30 minutes, if no symptoms are present, a slightly larger amount is eaten. Before each dose, careful evaluation is performed to look for any symptoms. If symptoms occur, the OFC might be stopped and emergency medications (antihistamines, oral steroids, adrenaline etc) are given if needed. Otherwise, the OFC continues until, typically, a meal sized portion is eaten. If there are no symptoms during an OFC, you will be free to go home within 1-2 hours of completing the OFC. In case of allergic symptoms, you might stay under observation for 2 – 4 hours from the time symptoms go away or improve, with longer observation periods required for patients with more severe reactions.

What are the risks?

The risks of OFC include an allergic reaction including anaphylaxis. There is no evidence that having an allergic reaction during an OFC makes future reactions worse.

Test / diagnostic pricing

Please contact the centre to discuss pricing.


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Overview

Average time of test

2-4 hours

Any prep needed?

Stop taking antihistamines 3 days before

Post-test recovery

Depends on any reactions caused by test

Risks

Allergic rash, swelling, stomach upset

Test / diagnostic pricing

Please contact the centre to discuss pricing.