Still others may require more extensive diagnostic efforts. Skin tests are performed by injecting a small amount of an allergen just under the skin. This test is no more painful than a mosquito bite, and will usually give an indication within twenty minutes of application. Skin testing is the most accurate type of diagnosis for most allergies. It may help to uncover food allergies, however, and is sometimes considered a useful diagnostic tool.
Food allergies can be difficult to pinpoint.
Sometimes the only way to accurately diagnose food allergy is by the process of elimination - to withhold a certain food substance from the diet for a period of time to observe whether symptoms abate. Of primary concern is successfully treating the allergy, once it is detected. In principle, the best way to treat an allergy is to remove the cause. Sometimes this is a practical solution, and sometimes it is not. If the allergy is caused by a pet, down pillow, wool sweater, or certain food, removal of the allergen will eliminate the symptoms.