Allergy
Introduction
Allergies occur when your immune system reacts to a foreign substance — such as pollen, bee venom or pet dander — that doesn't cause a reaction in most people.
Your immune system produces substances known as antibodies. Some antibodies protect you from unwanted invaders that could make you sick or cause infection.
When you have allergies, your immune system makes antibodies that identify a particular allergen as harmful, even though it isn't. When you come into contact with the allergen, your immune system's reaction can inflame your skin, sinuses, airways or digestive system.
Symptoms
- Sneezing
- Itching of the nose, eyes or roof of the mouth
- Runny, stuffy nose
- Watery, red or swollen eyes (conjunctivitis)
- Tingling mouth
- Swelling of the lips, tongue, face or throat
- Hives
- Anaphylaxis
Anaphylaxis
Some types of allergies, including allergies to foods and insect stings, have the potential to trigger a severe reaction known as anaphylaxis. A life-threatening medical emergency, this reaction can cause you to go into shock. Signs and symptoms of anaphylaxis include:
- Loss of consciousness
- A drop in blood pressure
- Severe shortness of breath
- Skin rash
- Lightheadedness
- A rapid, weak pulse
- Nausea and vomiting
Cause
Test and diagnostic
- Skin test. Your skin is pricked and exposed to small amounts of the proteins found in potential allergens. If you're allergic, you'll likely develop a raised bump (hive) at the test location on your skin. Allergy specialists usually are best equipped to perform and interpret allergy skin tests.
- Blood test. A blood test that's sometimes called the radioallergosorbent test (RAST) can measure your immune system's response to a specific allergen by measuring the amount of allergy-causing antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to possible allergens.
TREATMENTS AND DRUGS
- Allergen avoidance. Your doctor will help you take steps to identify and avoid your allergy triggers. This is generally the most important step in preventing allergic reactions and reducing symptoms.
- Medications to reduce symptoms. Depending on your allergy, allergy medications can help reduce your immune system reaction and ease symptoms. Medications can include over-the-counter or prescription medications in the form of oral medications, nasal sprays or eyedrops.
Immunotherapy. For severe allergies or allergies not completely relieved by other treatment, your doctor may recommend allergen immunotherapy. This treatment involves a series of injections of purified allergen extracts, usually given over a period of a few years.
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