General Information

• During your allergy assessment your doctor will ask several questions about your reaction to determine if there is an underlying allergy to a certain food
• The history of the reaction is the most important tool that your doctor will use to help determine if you / your child has an allergy
• The skin prick test (SPT), blood test and oral food challenge help confirm the presence of an allergy to a certain food
• Your doctor will never perform SPT to foods that you / your child are eating. The fact that the food is being eaten means there is no allergy
• Performing a SPT before a food is eaten (ex. skin testing to peanut before a child has actually eaten a peanut) is strongly discouraged because the test can be positive when there is no allergy
• SPT is the most common allergy test performed in an allergy clinic by specially trained allergist - It is a simple, safe and quick test, providing results in 15 minutes
• One week before the appointment, you / your child need to avoid antihistamines such as Benadryl, Reactine, Claritin, Aerus and Allegra because these medications will interfere with the test
• Many cough medications and decongestants also have antihistamines and should also be stopped one week before the appointment
• If antihistamines are not stopped one week before the appointment the SPT may not be done - The test can be performed on all ages including babies
• The number of tests will vary depending on the suspected allergy, as few as 3 or up to 15 tests may be performed depending on the suspected food

Skin Prick Test Procedure

• Two control samples are included to make sure that the test has worked:
  • One control will cause an itchy bump in all people
  • The other control is water and should not cause an itchy bump
• The test is performed on the inside of the forearm but in some cases it may be carried out on another part of the body such as the back
• The steps for the SPT include the following:
  • Cleaning the skin with an alcohol swab
  • A pen or marker will be used to label the skin and identify the foods to be tested
  • Tiny liquid drops will be placed on the skin
  • The skin is then pricked through the drop using a metal device called a lancet (this is not a needle)
  • The doctor or nurse will return in 15 minutes to interpret the test
• The test may feel a little sharp but is generally not painful and does not cause any bleeding - Any allergies will cause a localized red bump that is itchy and usually appears within 5 to 15 minutes
• The bumps will be measured with a ruler by the doctor or nurse
• These itchy bumps usually go away within 30 minutes
• The test is very safe in most people but certain people may not be suitable for the SPT such as those with active wheezing. Your doctor will decide if it is safe to do the test

Allergy Bloodwork

• Bloodwork may be requested by your doctor to help determine if there is a food allergy
• The results are usually available in 2 - 3 weeks

Oral Food Challenge

• The oral food challenge (OFC) is used to confirm a food allergy or show that the food allergy is outgrown. Your doctor will decide if an OFC is needed
• With an oral challenge, only one food is tested at a time
• This test has the potential to cause a serious reaction and should ONLY be performed by a trained allergist at a medical facility such as the hospital or clinic
• The test must be performed when you / your child is feeling well
• During the OFC, you / your child will be fed the food in measured doses, starting with a very small amount and increasing with each step
• You / your child will be monitored closely for signs of an allergic reaction - If a reaction occurs treatment will be provided by your doctor
• Please see the oral food challenge patient handout for more information