Food challenge in the allergy clinic (1307)

What is a food challenge?

It is the best test to find out if a patient is allergic to a certain food. It can also tell us if the patient has outgrown the allergy or is still allergic.

When is a food challenge done?

• When skin or blood tests meet required parameters or are negative.
• When the patient’s history leads us to think they will be able to handle the food.

Why is it done in the clinic?

• There is a risk for an allergic reaction. The clinic has supplies and staff who are trained to treat an allergic reaction.

What happens during a clinic food challenge?

• Questions will be asked and a physical exam will be done.
• The patient will have a breathing test if they have asthma or breathing problems.
• A small amount of the food is rubbed on the lower lip. If there is no reaction, the patient will eat a small amount of the food. Bigger amounts will be eaten every 15 minutes. This often happens in 4 or 5 steps.
• If the patient has a reaction, the challenge is stopped and the reaction is treated.
• A clinic food challenge may last 3 to 4 hours if there is not a reaction. It may be longer if the patient has a reaction.
• The patient will stay for at least 30 minutes after eating the last dose of food.

How do I prepare for a clinic food challenge?

• Keep taking all medicines as prescribed. This includes antihistamines.
• Bring the food to eat for the challenge. You will be told what to bring.
• You may also bring snacks and drinks that you have eaten before.
• Bring activities or a book.

Who should not have a food challenge?

A food challenge should not be done:

• If the patient is sick or is coughing, wheezing or having breathing problems. The patient may need to reschedule. This is for the patient’s safety.
• Call the clinic if albuterol has been used in the last 3 days. You do not need to call if Albuterol was used for exercise or activity within 3 days of the challenge.
• If the patient is taking beta blocker medicines for high blood pressure, migraine headaches, or eye drops for glaucoma. Common names are: Propranolol, Metoprolol, Atenolol, Timolol or Betaxolol.

What are the risks?

Mild reactions may happen during or after the challenge. They include rash, a few hives, eczema that gets worse, diarrhea, vomiting once, sneezing, stuffy nose, and runny nose, a change in behavior or headache.

Serious reactions do not happen often, but they can lead to death if not treated. Tell the nurse right away if there are any of the following:

• Hives: Rash, swelling or itching of more than one part of the body.
• Swelling: Any part of the body, inside or out. This includes the mouth, tongue or throat. It can be one or many parts of the body.
• Breathing problems: Shortness of breath, coughing, wheezing or chest feeling tight.
• Other: Constant sneezing, feeling dizzy, stomach ache, nausea, constant vomiting, severe diarrhea, or just not “feeling right.”

Anaphylactic shock is the most serious allergic reaction. It can be a combination of any of the above symptoms and can be life threatening. It can happen in a few minutes or up to 24 hours after the food has been given. It is important to watch for anaphylaxis, but it is does not happen often. Call 9-1-1 if any of these symptoms happen after leaving the clinic!

What happens if there is a reaction?

• The food challenge will be stopped and the reaction will be treated.
• For a mild reaction, an antihistamine like cetirizine (Zyrtec®) may be given.
• If there is a serious or anaphylactic reaction, emergency medicine will be given right away. The medicine is called epinephrine. The patient may need to be transferred to the emergency room if 2 doses of epinephrine are given.
• If a reaction happens during the challenge, the patient will need to keep avoiding the food. Plans for follow-up care or testing will be made.

By signing the consent form, permission has been given to the provider to do a food challenge and treat any reaction.

What happens after a clinic food challenge?

• The patient should not eat the food for 24 hours. Watch for a delayed reaction. This is rare, but still possible.
• If there is a reaction at home, take medicine to treat the reaction according to the discharge instructions. Go to the emergency room if needed. Call the Allergy Clinic.
• If there is no reaction, the patient should be given 1 to 2 servings of the food every day for 2 weeks.
• If the food is eaten at home with no reaction for 14 days, the patient is no longer allergic to the food. The patient should eat at least 1 to 2 servings of the food each month. This will let the patient keep eating the food and prevent the allergy from coming back.
• Call the Allergy clinic after the food has been eaten for 14 days. The allergy will be removed from the patient’s allergy list. A letter that the food is safe can be requested for school or day care.