What Are Allergies?
Allergies are a condition that occurs when the body’s immune system sees a substance as a harmful “invader” and overreacts to it. The substances that cause allergic reactions are called allergens, which are what trigger an immune response, also called an allergic reaction.
What Are Symptoms of Allergies?
Common allergy symptoms include:
- Itchy, watery eyes
- Itchy nose
- Runny nose
- Sneezing
- Rash
- Hives
- Swelling
- Redness
- Stomach cramps
- Vomiting
- Diarrhea
- Bloating
- Pain
- Tongue swelling
- Cough
- Swelling in the mouth and throat/throat closing
- Wheezing
- Chest tightness
- Shortness of breath
- Lightheadedness or fainting
- A sense of “impending doom”
- Low blood pressure (hypotension)
- Rapid and weak pulse
Some of the above symptoms may be severe and can be signs of a serious and potentially life-threatening allergic reaction (anaphylaxis). Sudden, severe, widespread reactions require emergency care. Call 9-1-1 if you suspect someone is having a severe allergic reaction.
What Causes Allergies?
Allergic reactions result when the body’s immune system sees a substance as a harmful “invader” and overreacts to it.
Allergens can enter or come into contact with the body in several ways:
- Inhaled, such as pollen, dust, mold, and dander
- Ingested, such as foods and medications
- Injected, such as from injected medications or insect bites and stings
- Absorbed through the skin, such as from plants like poison ivy, latex, metals, and ingredients in household products
Common allergens include:
- Pollen
- Medications
- Certain foods
- Peanuts
- Eggs
- Tree nuts, such as walnuts, almonds, pine nuts, brazil nuts, and pecans
- Soy
- Wheat
- Fish and shellfish (more common in adults)
- Dairy products/milk (more common in children)
- Insects stings and bites (bee, wasp, fire ant, mosquito, tick)
- Household pests (cockroach and dust mite)
- Latex
- Mold
- Pet (dog or cat dander, saliva, and urine)
- Plants such as poison ivy, sumac, and oak
How Are Allergies Diagnosed?
Allergies are diagnosed starting with a medical history and physical exam.
Tests used to diagnose allergies may include:
- Skin prick test
- Intradermal skin test
- Blood tests (specific IgE)
- Physician-supervised challenge tests
- Patch Test
What Is the Treatment for Allergies?
The first line of treatment for allergies is to avoid known allergens if possible. When this is not possible, medications used to treat allergies include:
- Nasal corticosteroids (nose sprays) for nasal allergies
- Antihistamines to help with sneezing, itching, runny nose, and hives often caused by seasonal and indoor allergies
- Mast cell stabilizers to help with itchy, watery eyes, or an itchy, runny nose
- Decongestants to reduce nasal congestion
- Corticosteroid creams or ointments to relieve itching and rash
- Oral corticosteroids to reduce swelling and stop severe allergic reactions
- Epinephrine is administered during a life-threatening anaphylaxis (severe allergic reaction)
Immunotherapy is a type of treatment that is effective for some patients. There are two common types of immunotherapy:
- Allergy shots
- Involves injections of allergens in an increasing dose over time to desensitize the patient to that allergen
- Allergy shots are often used to treat allergies to pollen, pets, dust, bees or other stinging insects, and asthma
- Allergy shots are not usually effective for allergies to food, medicines, feathers, or for hives or eczema
- Sublingual immunotherapy (SLIT)
- Small doses of an allergen are administered under the tongue to improve tolerance to the allergen and reduce symptoms
- SLIT is effective in treating nasal allergies and asthma caused by dust mites, grass, and ragweed
How Do You Prevent Allergies?
Controlling exposure to allergens is the best way to prevent allergic reactions.
- Avoid allergens when possible
- Keep a diary of when allergic reactions occur to help figure out triggers
- Take allergy medications as prescribed
- Keep epinephrine auto-injectors on hand at all times if you are at risk for severe allergic reaction (anaphylaxis)
- Wear a medical alert bracelet if you have ever had an anaphylactic reaction
- Have an emergency plan for what to do in case of anaphylaxis
Health Solutions From Our Sponsors
From ![WebMD Logo](https://images.medicinenet.com/images/promo/logo_webmd.gif)
Allergies Resources
Featured Centers
Health Solutions From Our Sponsors
AAFA.org