Environmental Allergy

Introduction

Runny noses, itchy watery eyes, and sneezing bother many Americans with environmental allergies, especially during pollen season.  While outdoor allergies from grass, weeds, and trees may be seasonal, indoor allergies from dust mites and pet dander can cause problems all year round.  There are many ways you can reduce your exposure to allergens (things that cause allergies).  Immunotherapy shots are a way to desensitize the body and can provide permanent freedom from allergies for many people.

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Anatomy

Your immune system usually fights germs to keep you healthy.  If you have allergies, your immune system overreacts to ordinary substances that normally are not harmful.  The substances that trigger an allergic reaction are called allergens.

When you are exposed to an allergen, your white blood cells produce antibodies.  The antibodies trigger the release of histamine and other chemicals in your blood called mediators.  The mediators cause the symptoms of the allergic reaction.
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Causes

There are many causes of environmental allergies.  Outdoor seasonal allergies originate from plant pollens during the growing season.  Year-round indoor allergies are present at any time of the year.

Outdoor seasonal allergens include pollen from:
• Trees
• Grass
• Weeds

Year-round indoor allergens include:
• Dust mites
• Mold
• Cockroaches
• Pet Dander
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Symptoms

The symptoms of environmental allergies vary from person to person.  Common allergy symptoms include a runny nose, sneezing, itchy watery eyes, and bags under the eyes.
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Diagnosis

An allergist can diagnose environmental allergies by reviewing your medical history and conducting a physical exam.  A blood test or skin test is used to identify specific allergens. For the skin test, your allergist will inject a small amount of allergen into your skin.  After a short time, a red bump will appear if you are allergic to the substance. 
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Treatment

You should adjust your lifestyle to avoid environmental allergens as best you can.  Your doctor may recommend over-the-counter or prescription medications, including antihistamines, corticosteroids, and decongestants.  There are many different types of allergy medications, and you may have to try a few different ones before you find the best ones for you.

Immunotherapy may be recommended for people with severe environmental allergies or after medication treatments have failed to treat symptoms.  Immunotherapy involves receiving a series of injections of small amounts of allergens to desensitize the body’s response to the allergens.  Over a period of about three to five years, immunotherapy injections can eliminate or reduce environmental allergic reactions for many people.

Your allergist may prescribe an emergency shot of epinephrine (EpiPen, EpiPen Jr., Twinject) for you to carry with you at all times if you have severe allergic reactions.  You should instruct those around you how to give you the emergency shot if you are unable to do so.  You should receive emergency medical treatment even if you used the shot.
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Prevention

You can help prevent allergies by avoiding the allergens that you can.  Here are some tips:
• Take a shower after spending time outdoors.
• Wash pets once a week.
• Wash bed linens in the hottest water possible.  Do not dry laundry outside. Use special allergy covers on pillows and mattresses.
• Keep windows shut and use an allergen filter in your central air conditioner and heating system. Keep the humidity in your house as low as possible.
• Vacuum rugs and keep floors clean.

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Am I at Risk

The following are risk factors for environmental allergies:
• Allergies can run in families.  If other members of your family have allergies, you have a risk of developing allergies. 
• If you have one type of allergy, you are more likely to have another type of allergy.
• If you have asthma, you have an increased risk for allergies
• Children are more likely to develop allergies, although allergies can occur at any age.

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Complications

Environmental allergies can contribute to other medical conditions including asthma, rashes, sinus infections, ear infections, and lung infections.
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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on February 16, 2022. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.