Diagnosis of an allergic reaction begins with a medical history and physical examination. In some cases, special skin tests or other allergy testing may be needed to determine the trigger. In skin testing, small amounts of the suspected substance can be injected under the skin. If a person is allergic to the substance, a skin reaction usually occurs. An allergic reaction has no long-term effects if the trigger is avoided.
Many allergies are mild and pose little threat to the affected person.
Some allergies are life threatening and may cause death. Allergic reactions are not contagious and pose no risk to others. Reassure the person to calm him or her down. Anxiety can increase the severity of the reaction. The trigger should be identified if possible and removed.