An immune-mediated reaction to a substance that is normally harmless to most people.
An allergic reaction occurs when the immune system responds inappropriately to an allergen such as a food protein, pollen, medication, insect venom, or animal protein. The reaction can involve different immune mechanisms and may produce symptoms affecting the skin, respiratory system, digestive system, or other parts of the body.
Allergic reactions range from mild symptoms such as itching, sneezing, or hives to anaphylaxis, a potentially life-threatening systemic reaction.
COMMONLY CONFUSED WITH
- Autoimmune reaction: targets the body’s own components, whereas an allergic reaction is directed against an external allergen.
- Intolerance: an adverse reaction that does not involve the same immune mechanism as an allergy.
- Hypersensitivity: a broader term encompassing immune reactions that cause excessive or harmful effects; allergy is one form.
SEE ALSO
