The U.S. National Library of Medicine offers this look at different types of allergy diagnostics:

• Skin tests, which involve placing potential allergens under the skin to look for any reaction. Skin tests can gauge pollen, food, mold and other potential allergens.
• An elimination diet test looks for foods that can be causing allergy symptoms, and involves removing foods from the diet one at a time.
• Blood tests can be used to detect antibodies to potential allergens in the blood.
• Provocation (challenge) testing exposes someone to particular allergens in a controlled environment to see if there is a reaction.

-- Diana Kohnle