What is a food challenge?

A food challenge consists of having a patient eat a food suspected of previously causing symptoms in a controlled fashion under medical supervision. This is done by feeding gradually increasing doses of the suspected food at predetermined time intervals (such as every half hour) until a reaction occurs or a normal amount of the food is eaten without causing symptoms. Food challenges can be performed in a variety of ways.

In an open food challenge (OFC), both the patient and medical staff are aware that the patient is eating the suspected food. For example, a child receiving an OFC to egg might be given increasing doses of scrambled egg every 30 minutes until a whole egg is ingested.

In a single-blind placebo-controlled food challenge (SBPCFC) the medical staff is aware of what the patient is being fed, but the patient is not. A child receiving a SBPCFC to egg receives egg masked by concealing it in another food. The medical staff knows if and how much egg is contained in each challenge dose, but the patient and the patient’s family do not. Each dose could either contain concealed egg, or a placebo. However, the final dose of any food challenge is the open ingestion of a normal portion of the suspected food. SBPCFCs are performed to eliminate bias on the part of the patient and/or the patient’s family.

In a double-blind placebo-controlled food challenge (DBPCFC) neither the patient nor the medical team involved in administering the challenge is aware of what the patient is being fed. The DBPCFC is performed to eliminate both patient and observer bias. For the safety of the patient at least one medical care provider not directly involved in the challenge must be aware of the challenge contents even in a DBPCFC. The final dose of the DBPCFC is a normal portion of the suspected food ingested openly.

A food challenge is completed when the patient has an obvious reaction to the food or when a normal portion of the food has been ingested openly without symptoms. The length of time a patient is kept for observation after completion of the challenge depends upon several factors including the timing and severity of previous reactions. The results of the challenge are thoroughly reviewed with the patient and his or her family and all questions are addressed in light of the results of the challenge.

Should I consider a food challenge for my child or myself?

This information has been approved by Dan Atkins, M.D. (December 2006).