Oral or inhaled corticosteroids do not interfere with skin prick tests. Skin prick tests are less reliable for children under the age of three. They are not often used in this age group, except in the context of a specialist allergy clinic. These require a sample of blood that is sent to a laboratory for testing. They are used more often in the diagnosis of food allergy or anaphylactic reactions.
Results are available within a few days to a week depending on which test is used.
Food challenge tests. These tests should only be performed in specialist settings. Small samples of suspected foods are disguised and then eaten by the individual. Your body's response to the food is assessed by the doctor. Simple exclusion diets involve the avoidance of suspected foods for a few weeks.