Environmental Allergy (Allergic Rhinitis) and Hay Fever Medications
What Are Allergies?An allergic reaction occurs when the immune system responds in an abnormal fashion to a substance that is foreign to the body. The immune system normally protects the body from harmful agents like bacteria and toxins. The body's abnormal response to a substance that is usually harmless (called an allergen) is called a hypersensitivity reaction, or an allergic reaction. Generally, these reactions are due to interactions between the allergen and the family of proteins, IgE (immunoglobulin E), resulting in activation of cells in the body called mast cells and basophils. These cells release chemical messengers in the body that cause the symptoms of an allergic reaction. Many substances in the environment can become allergens but only in genetically susceptible people. Dust mites, molds, animal hair or danders, pollens, medications, foods, and insect venoms are examples of common allergens. Reactions may be in the nose (hay fever), eyes (conjunctivitis), chest (asthma), or it can be systemic (anaphylaxis), meaning it can involve the entire body. Allergic rhinitis is an inflammation of the nasal membranes (along with membranes of the eyes, eustachian tubes, middle ear, sinuses, and throat) due to an allergic reaction. It is the most common cause of inflammation in the nose (rhinitis). Approximately 20% of the U.S. population is believed to suffer from allergic rhinitis. Next: What Are the Risks of Allergies? » |
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Severe Allergic Reaction (Anaphylactic Shock) »
Severe Allergic Reaction Overview
Anaphylaxis is a severe allergic reaction that occurs rapidly and causes a life-threatening response involving the whole body. This reaction can lead to difficulty breathing and shock ultimately leading to death.
For an anaphylactic reaction to occur, you must have been exposed in the past to the substance that causes the reaction, called the antigen. This is called "sensitization."
- A bee sting, for example, may not cause an allergic reaction the first time.
- Another bee sting may produce a sudden, severe allergic reaction known as anaphylaxis or anaphylactic shock.
You may develop sensitivity and anaphylaxis to a substance that you have been exposed to many times in the past without a reaction, and often people don't recall the previous exposure.
Severe Allergic React...
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Allergic Rhinitis »
Allergic rhinitis is a common health problem for which many patients do not seek appropriate medical care.


