In some patients food or drug challenges are used. Please allow 4-5 hours in clinic for a complete challenge. Here, a patient is given increasing amounts of the allergen in question at regular intervals until a normal serving or dose is achieved. The patient is checked on regularly. Once this has been achieved, the patient is still observed in the clinic for two hours afterwards to make sure that there is not an adverse reaction. If you believe you will be undergoing a challenge, please remain off medications such as antihistamines for at least 5-7 days prior to testing.