A graded challenge (oral supervised challenge) is the most accurate means of diagnosing food/drug allergies and remains the 'gold standard'. In essence, a supervised food/drug challenge entails no more than exposing the patient to incremental doses of one or more food/drug allergen(s), followed by ongoing consumption of the food/drug at home over the following days. There are normally 5 to 6 dose increments in a food challenge. The top dose aims to approximate an age-appropriate portion of the food/drug. Open or unblinded food/drug challenges are usually all that is required to determine food/drug allergy or intolerance.
Oral food/drug challenges (OFCs, ODC'd) are generally a safe procedure with the proviso that they should be performed by experienced health care workers and with caution. Severe allergic reactions are extremely rare but should be anticipated. All challenges are performed on premises with access to a PICU. OFCs and ODC's are time consuming but highly informative procedures; challenges are only undertaken when allergy tests do not provide a secure answer with regard to diagnosing an allergy or intolerance.
We offer challenge services in one of two locations
Children's Allergy Service at St Thomas' Hospital, Elizabeth Ward, for an NHS appointments, you will need to be referred by your GP to St Thomas' NB - you will then first be seen in Outpatients before being booked in on a second occasion for the challenge.
The Portland Hospital, on Thursdays and Saturday mornings. Louise Cameron is the Specialist Nurse who will co-ordinate/perform these nurse-led challenges. Louise can be contacted on Louise.Cameron@hcahealthcare.co.uk There is more information on this process in the attachment below.
Preparation for the Challenge
OFCs and ODC's must be postponed if the individual is unwell. Antihistamines must be stopped 3 days before the challenge. Despite the many websites and texts with detailed common recipes and placebos, there is no replacement for an experienced, on site paediatric dietitian to deal with novel scenarios which may arise when performing Oral Food Challenges. We provide this level of expertise.
Food challenges are most frequently performed baked(?) egg, scrambled egg, milk, sesame, nuts, wheat, fish, shellfish.
Drug Challenges are most frequently performed to: antibiotics e.g. Amoxicillin, Analgesics e.g. Ibuprofen, Paracetamol and Anaesthetics e.g. Lignocaine.