When your body takes harmless substance in the environment as intruders, it becomes hypersensitive and launches a war. That results in allergic reactions. Things that cause allergic reactions are called allergens, mostly of them are proteins in the environment or in the foods. The immune system produces Immunoglobulin E (IgE) antibodies that recognize and bind to the allergens. These IgE-allergen complexes then bind to specific cells and trigger these cells to release substances that cause allergic reactions, including histamine and other chemicals. Sometimes, other allergic mechanisms that do not involve IgE can happen.
Allergic reactions may be mild and localized, such as sneezing, running nose, itchy swollen eyes, scratchy throat, wheezing, eczema, hives, upset stomach, etc, as in most cases. But occasionally they may become serious or even life threatening, manifested as throat swelling, trouble breathing, blood pressure drop, or multiple systems reacting at the same time. We call these types of reactions anaphylaxis, which are more commonly seen in food allergy, bee sting allergy, or medication reactions.
Below listed some common allergic diseases:
- Nose and Eye Allergies
- Eczema (atopic dermatitis)
- Contact dermatitis (contact skin allergy)
- Urticaria (hives) and angioedema
- Food allergy
- Drug allergy
- Insect sting allergy
When you go to see an allergist for an allergic condition, your allergist may perform allergy tests based on the history, which is the most important factor in interpreting test results, as the test results may be positive but they may not have clinical relevance. Skin tests and blood tests are commonly done to detect IgE-mediated hypersensitivity.
Treatments for allergies include allergen avoidance and medications. Typically used medications are: antihistamines and decongestants (by mouth, nasal sprays) to reduce symptoms, corticosteroids (by mouth, nasal sprays, on the skin) that cool off the overactive immune system, and epinephrine (injection inside muscle) as a life-saving agent in anaphylaxis. For patients with allergic rhinitis / sinusitis and allergic asthma that do not respond adequately to medications, or patients who have experienced systemic reactions to insect stings, allergy shots (immunotherapy) can be used to desensitize the bodies’ responses.