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.
Safety
Oral food/drug challenges 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.
Locations
We offer challenge services in one of two private patient facilities:
Great ormond Street International and Private Facility
Challenges are udertaken on Monday and Tuesday of each week.
Portland Hospital
The Portland Hospital, on Thursdays. Melanie Davies is the Specialist Nurse who will co-ordinate/perform these nurse-led challenges. Prof Du Toit will be on hand in case of severe allergic reactions.
Private Challenge At the Evelina London Childrens Hospital
Children's Allergy Service at St Thomas' Hospital, Private Patient Facility. Our office can provide details for this service.
Preparation for the Challenge
OFCs and ODC's must be postponed if 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 to 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.