Definition of Allergies
Allergies are unusual reactions to simple nontoxic substances. The substances that cause allergy are known as allergens, may be inhaled with breath, swallowed, or exposed to the skin.
The most common allergens that cause troubles are: pollens, mold spores, house dust mites, food stuffs, insect stings or bite, some species of plants, insect spores, latex rubber, odor, viruses, bacteria, medications and atmospheric conditions (like too hot or cold). Allergic reactions can occur in more than one area, such as sneezing along with the skin rashes and may include more than one symptom.
Normally, the body has its own system which enables it to learn and defend itself through encountering, and remembering enemies one by one. For decades, medical science has taken advantage of this ability by using vaccination to create immunity, the immunologic memory of a disease. Allergic reactions happen when immune system incorrectly recognizes harmless foreign particles as potentially harmful.