1. 10 Common Allergy Triggers Slideshow Pictures
2. Take the Quiz on Allergies
3. Nasal Allergy Relief Slideshow: Products That Work

Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Full Profile

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

View Full Profile

In this Article

• What is hay fever? What are the symptoms and signs?
• Why does an allergic reaction occur?
• What causes allergic rhinitis?
• When and where does allergic rhinitis occur?
• How is allergic rhinitis diagnosed, and how are allergies identified?
• How are allergies treated?
• Hay Fever At A Glance
• Find a local Asthma & Allergy Specialist in your town
• Hay Fever Index

Since allergic rhinitis is frequently caused by pollen, symptoms occur when pollen is in the air. Trees primarily pollinate in the spring, while grasses pollinate in the spring and summer. Weeds usually pollinate in the late summer and fall. Of all allergy sufferers in the United States, 75% are allergic to ragweed, 50% are allergic to grasses, and 10% are allergic to trees. Of course, many people are allergic to other substances such as mold spores, animal protein, and mites, to name a few. Food is an uncommon cause of allergic rhinitis. If you wish to know the pollen count in your area, this information can often be found in the newspaper in the weather section or you can access the National Allergy Bureau's pollen count information at their web site (http://www.aaaai.org/nab/index.cfm).

If a person is experiencing the typical symptoms of hay fever, a consultation with an allergy specialist can help identify the offending substances. Since the ideal way to manage an allergy is to avoid the substances that cause allergic reaction, it is therefore very important to first identify these substances (allergens). Many allergens can be suspected from information obtained in a patient's particular history. For example, if symptoms usually worsen with exposure to cats, then cat dander protein is a probable allergen causing the symptoms. If cutting grass is associated with the onset of symptoms, then grass allergy is probable. A patient's history of reactions is very important in determining his/her unique allergies.

Because the identification of allergens is important and often difficult to pinpoint, skin testing is often needed to identify exactly the specific substance causing the allergy. Skin testing is now done with minimal discomfort and is performed as follows:

• A small amount of the suspected allergy substance is placed on the skin.



• The skin is then gently scratched through the small drop with a special sterile needle. This is known as the prick-puncture method and is typically used for initial evaluations. A second method, known as the intradermal method, involves injection of a small amount of the test substance into the skin. Intradermal testing is more sensitive but also tends to lead to more false-positive results.



• If the skin reddens and, more importantly, swells, then an individual is said to be "sensitized" to the particular allergen. If typical symptoms occur when a sensitized individual is exposed to the suspected substance, then allergy to that substance is probable.



• The skin testing described is tolerated by the youngest of patients and should be the standard of testing.



• Skin testing is not indicated for people who are at risk of a severe (anaphylactic) allergic reaction, who have certain skin conditions, or who are taking certain medications.

A number of blood tests are also available to aid in the diagnosis of allergy. These blood tests may be useful in people who cannot be skin tested due to skin diseases, who are taking medications that interfere with skin testing, or who are at a high risk of having an anaphylactic reaction to skin testing. These blood tests typically use various techniques to look for IgE antibodies in the blood and by inference suggest allergy in the tissues. If the allergy testing agrees with the history of symptoms upon exposure to the substance, then a diagnosis of allergic rhinitis is likely.