Allergy – Overview

What Are Allergies?

An  allergy is a reaction your body has when it comes into contact with a  specific substance, called an allergen, to which you are overly sensitive. There are many different types of allergies and you can  develop them through a variety of different exposures, such as through  touch, breathing, eating or drinking the allergen. More than 80 percent  of allergies are ‘indoor’ allergies or ‘outdoor’ allergies, also called  seasonal allergies.

Why Allergies Happen

There are three factors involved in an allergic reaction. First, the allergen  to which you are sensitive must be present in sufficient quantity to  trigger a reaction. Second “mast cells” in your body release chemicals.  Finally, there is immunoglobulin, or IgE. This is a type of protein that  coats your mast cells and is made by your immune system to resist  foreign substances.

When  you have an allergic reaction, your immune system produces the IgE that  is specifically associated with that particular allergen. This causes  your mast cells to release chemicals, such as histamines and  leukotrienes, that ultimately cause some of the allergic symptoms you  may feel.

Outdoor Allergies

Common  outdoor allergens include pollen particles from trees, plants, grass,  or weeds. Outdoor allergies are also called seasonal allergies because  you typically experience these allergies in the spring, late summer and  fall, when plant growth is at its height, but they can occur year round  in certain climates.

Indoor Allergies

Indoor  allergies are triggered when allergens like dust, mold or pet dander  are inhaled or touched. Allergies to smoke, cockroaches and rats can  also develop.

Common Allergy Symptoms

  • Sneezing
  • Runny nose
  • Nasal drip
  • Swelling in the nose and around the eyes
  • Itchy, watery eyes
  • Congestion
  • Headaches
  • Hives
  • Sleeplessness
  • Fatigue

In  people with asthma, allergies can sometimes worsen their asthma as  well. Prolonged episodes of allergic reactions may cause chronic congestion, changes in your sense of smell and taste, and swollen  blue-colored skin underneath your eyes called “allergic shiners.”

Risk Factors

In  general, allergies will most likely develop during childhood, although  they can begin at any age. Factors that increase your risk of developing  allergies include:

  • a family history of allergies and
  • exposure to cigarette smoke during the first year of life
  • firstborn status
  • birth during the pollen season
  • male sex
  • early introduction of formula and food (before 4 to 6 months)
  • early use of antibiotics and
  • exposure to indoor allergens, such as animal dander.


To determine if you have indoor or outdoor allergies, your doctor will ask you about your medical hjistory and your family’s history: exam your skin, face, and lungs: and then perform a skin, breathing, and/or blood test.

Preventing Allergic Reactions

Since there is no cure for allergies, the easiest way to control them is to limit contact with the offending allergen:

  • If  you have outdoor allergies, try to  stay indoors – especially on  dry, windy days between 10:00 AM and 4:00 PM  – during the seasons  when pollen is at its worst. Also try to avoid being outside at  sunset when mold spores drop to the ground. You can also go online or listen to the radio for a daily report on pollen and mold counts.
  • Wear clothing that is loose and light and then wash them with hot water after each use.
  • When  you are indoors, avoid rooms that may be more prone to mold, like  basements or saunas. Reduce moisture in your kitchen and bathroom  by fixing any leaks.
  • Use dehumidifiers throughout the house and a high-efficiency particulate air, or HEPA, filter in your bedroom.
  • Keep windows and doors closed during high pollen seasons and keep an air conditioner running.
  • Keep  your house clean. Change bedding and vacuum every week, and avoid  carpeting, stuffed animals or feather bedding in your bedroom.
  • Think  twice about getting a pet, or if  you have one, bathe it every  week, brush it often and keep your pet in areas that aren’t  carpeted. Having a hypoallergenic pet, which means a pet that  produces less dander, may also limit allergic reactions.
  • Avoid smoke.
  • Avoid perfumes and cosmetics that seem to make symptoms worse.

Treatments for Allergies

  • Antihistamines  may help relive sneezing, itching and runny nose, as well as  rashes or hives. They are most  effective if you use them on a  regular basis throughout allergy season.
  • Decongestants can reduce the stuffiness you feel in your nose and chest, but  probably won’t help you with itching or sneezing.
  • Eye drops may help with bloodshot, watery or burning eyes.
  • Corticosteroid  creams and ointments can relieve skin rashes or itchiness. Corticosteroid nasal sprays can help reduce nasal congestion. If  these don’t work, leukotriene inhibitors may also be an option.
  • Oral corticosteroids may help reduce swelling.
  • If  medication doesn’t solve your allergy problems, your doctor may  recommend a treatment called immunotherapy. This entails receiving  regular injections of an allergen over the course of      three to five  years to ultimately desensitize you.
SourcesAllergies. Bethesda, MD.: National Library of Medicine and the National Institutes of Health, 2009. (Accessed on July 19, 2010 at RD and Kemp SF. Clinical Manifestations and Epidemiology of Allergic Rhinitis (rhinosinusitis).UptoDate, April 2010, last reviewed May 20, 2011.Topic of the Month: Staying Ahead of Spring Allergy Season. Milwaukee, WI.: AAAAI, 2005. (Accessed on July 19, 2010 at

This  information for educational purposes only; this information is not meant as medical advice. Always consult your doctor about your specific health condition.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s