allergy
a state of hypersensitivity in an affected individual to a particular allergen, which produces a characteristic response whenever the person is exposed to the substance. In an unaffected person, antibodies present in the bloodstream destroy their particular antigens ( ALLERGENS ). However, in an affected individual this reaction causes some cell damage and there is a release of substances, such as HISTAMINE and BRADYKININ , which cause the allergic reaction. Example of allergies are dermatitis, hay fever, asthma and the severe response known as ANAPHYLAXIS .
An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are:
- Pollen
- Dust mites
- Mold spores
- Pet dander
- Food
- Insect stings
- Medicines
Normally, your immune system fights germs. It is your body's defense system. In most allergic reactions, however, it is responding to a false alarm. Genes and the environment probably both play a role.
Allergies can cause a variety of symptoms such as a runny nose, sneezing, itching, rashes, swelling, or asthma. Allergies can range from minor to severe. Anaphylaxis is a severe reaction that can be life-threatening. Doctors use skin and blood tests to diagnose allergies. Treatments include medicines, allergy shots, and avoiding the substances that cause the reactions.
allergy