explain how allergic reaction occurs

Answer 1

An allergic reaction occurs when the immune system mistakenly identifies a harmless substance, known as an allergen, as a threat to the body. The immune system's main function is to defend the body against harmful substances like bacteria or viruses. However, in the case of allergies, the immune system overreacts to the allergen and triggers an allergic reaction.

When a person with allergies is exposed to an allergen, such as pollen, pet dander, or certain foods, the body's immune system produces antibodies called immunoglobulin E (IgE). These antibodies recognize and bind to the allergen, activating specialized immune cells called mast cells and basophils.

Upon binding with the allergen, mast cells and basophils release various chemicals, including histamine, into the bloodstream. Histamine is primarily responsible for the allergic symptoms. It causes blood vessels to expand, leading to increased blood flow and swelling in the affected area. It also causes the tissues to become inflamed, resulting in redness, itching, and rashes. Additionally, histamine can stimulate nerve endings, leading to itching and discomfort.

The release of histamines and other chemicals further activates the immune system, leading to the production of more IgE antibodies and causing a cascade of inflammatory responses throughout the body. This immune response can manifest in various ways, depending on the allergen and the individual. Common allergic reactions include sneezing, runny or stuffy nose, itchy or watery eyes, hives, swelling, wheezing, coughing, shortness of breath, and gastrointestinal issues.

In severe cases, a life-threatening allergic reaction called anaphylaxis can occur. Anaphylaxis involves a rapid and severe immune response affecting multiple systems in the body, leading to symptoms such as difficulty breathing, lightheadedness, low blood pressure, rapid or weak pulse, vomiting, and loss of consciousness. Anaphylaxis requires immediate medical attention and the use of epinephrine to counteract the allergic reaction.

It is important for individuals with known allergies to avoid exposure to their allergens whenever possible and to carry appropriate medications, such as antihistamines or epinephrine, in case of accidental exposure. Allergies can be managed through avoidance strategies, medications, and in some cases, immunotherapy to desensitize the immune system to specific allergens.