Allergic Reaction: The hypersensitive response of the immune system of an allergic individual to a substance that is usually harmless.
Any foreign substance (an allergen) can cause allergic reaction in some people. Allergic reactions are caused by the interaction of a person’s immune system with outside allergen that gets inside our bodies. When an allergen, or trigger substance enters into the body, it causes the body’s immune system to develop an allergic reaction in an individual with an allergy to it. Some examples of allergens include: dust, pollen, plants, some medications, certain foods, viruses and bacteria. These allergens can enter into the body by being inhaled, ingested (swallowed), touched, absorbed, or injected.
A healthy immune system protects the body against bacteria, viruses, and other harmful toxins. However, an overreaction to a harmless substance such as an allergen, a mild antigen, is called allergic response (also called a hypersensitivity reaction) or allergic reaction.
An allergic reaction may not happen the first time you are exposed to an allergy-producing substance (allergen).It may only produce a mild reaction, repeated exposures may lead to more serious reactions. Allergic reactions vary from one person to another. Hypersensitivity reaction can range from a slight annoyance such as an itchy rash and runny nose, to a fatal incident.
Types of Allergic Reaction
The rate and types of hypersensitivity reaction indicate different immune responses. The look and feel of an allergic reaction depends on the body part involved and the severity of the reaction. Allergic (hypersensitivity) reactions are classified into four types:
• Type 1: Immediate Hypersensitivity (Anaphylactic)
• Type II: Hypersensitivity (Antigen-Antibody Reaction)
• Type III. Hypersensitivity (Immune Complex)
• Type IV: Cell-meditated Hypersensitivity (Delayed type)
Symptoms of Allergic Reaction
The clinical picture and the symptoms of an allergic reaction depend on the part of the body which is involved and how severe the reaction is. Some reactions affect many areas, while others just affect a particular single area. Reactions to the same allergen vary from one individual to another. Almost anything can trigger a hypersensitivity or allergic reaction.
Most allergic reactions are mild, and home treatment can relieve many of the symptoms. Symptoms and signs of hypersensitivity reaction include any, some, or many of the following:
Symptoms of the allergic reaction – Skin: Allergens that touch the skin can cause skin rash, hives, blisters skin redness, itchiness, and swelling.
Allergic reaction symptoms – Lungs: respiratory symptoms coughing, wheezing, chest tightening
Symptoms of the allergic reaction- Swollen Face: Facial swelling is a sign of hypersensitivity reaction. Allergic reactions can lead to leaks in the subcutaneous capillary beds that can result in swollen face and eyes.
Allergic reaction symptoms – Nose: Allergic reactions may cause frequent sneezing, congestion, and an itchy or runny nose in some people.
Symptoms of the Allergic Reaction – Eyes: Redness and tearing, itching, swollen eyelid, discharge (watery or thick).
Allergic Reaction Symptoms – Stomach: Cramps or pain in the abdomen, bloating, vomiting, and diarrhea.
The victims suffering allergic reaction must know how to get first aid if it happens to them. In rare cases, hypersensitivity reaction can be deadly. Anaphylaxis is the word used for a severe allergic reaction that occurs rapidly serious and rapid allergic reactions. Anaphylaxis is an extreme allergic reaction, which can be fatal and must be taken extremely seriously. Quick treatment can stop a dangerous hypersensitivity reaction.