Allergy is a physiological reaction caused when the immune system mistakenly identifies a normally harmless substance as damaging to the body.
Normally, the human body defends itself against harmful substances such as viruses or bacteria, but sometimes the defenses aggressively attack usually innocuous substances such as dust, mold, or pollen.
The immune system generates large amounts of the antibodies called immunoglobin E (IgE), a complex chemical weapon, to attack and destroy the supposed enemy. Each IgE antibody specifically targets a particular allergen – the substance that causes the allergy. In this disease-fighting process, inflammatory chemicals like histamines, cytosine, and leukotrienes are released or produced, and some unpleasant (and, in extreme cases, life-threatening) symptoms may be experienced by an allergy-prone person.
An allergic reaction may occur anywhere in the body, in the skin, eyes, lining of the stomach, nose, sinuses, throat, and lungs – places where immune system cells are located to fight off invaders that are inhaled, swallowed, or come in contact with the skin. Reactions may result in:
Although hundreds of ordinary substances could trigger allergic reactions, the most common triggers – called allergens – include the following:
Allergies can affect anyone, regardless of age, gender, race, or socioeconomic status. Generally, allergies are more common in children. However, a first-time occurrence can happen at any age, or recur after many years of remission.
There is a tendency for allergies to occur in families, although the exact genetic factors that cause it are not yet understood. In susceptible people, factors such as hormones, stress, smoke, perfume, or other environmental irritants may also play a role. Often, the symptoms of allergies develop gradually over a period of time.
Allergy sufferers may become so accustomed to chronic symptoms such as sneezing, nasal congestion, or wheezing, that they do not consider their symptoms to be unusual. Yet, with the help of an allergist, these symptoms can usually be prevented or controlled and quality of life greatly improved.
In addition to performing a clinical examination and taking a medical history, a physician may also use:
Specific treatment for allergy will be determined by your physician based on: