Signs and Symptoms of Hay Fever

• Itching of the face, mouth, eyes
• Sneezing
• Runny nose (clear, thin nasal drainage)
• Shortness of breath
• Wheezing

Daytime sleepiness and fatigue may occur due to impaired sleep. An extreme allergic reaction can result in anaphylactic shock, a life-threatening situation characterized by swelling in the airways and a drop in blood pressure.

Differential Diagnosis of Hay Fever

Often, the history of the symptoms can help to determine if they are caused by allergies rather than infection or another condition. Symptoms that recur each year around the same time (i.e., spring or autumn) and/or occur consistently with exposure to certain irritants (grasses, dust, cats) are classic for allergic rhinitis.

Allergy symptoms often resemble those of the common cold, however, a cold usually resolves within 10 days, while allergy symptoms can persist for weeks or months. Nasal discharge may be thick and yellow during a cold, while with allergies, it is usually thin and clear and is often associated with itching of the eyes, skin or mouth.

Perennial allergic rhinitis must also be distinguished from non-allergic, noninfectious forms of rhinitis, such as idiopathic (vasomotor) rhinitis, hormonal rhinitis, drug-induced rhinitis, and food-induced rhinitis.

Allergy Testing

Allergy skin testing involves the introduction of allergen through a break in the skin. Allergy testing helps to determine exactly which substances are causing the allergic response so that an individualized treatment plan can be developed. The first skin test for allergies was performed by a physician names Charles H. Blackley in 1865.

The old approach of "scratch testing" has largely been abandoned due to discomfort, poor reproducibility and the possibility of scarring.

The current approaches to skin testing include:

• Skin Prick Testing - This test involves a series of injections in the skin of the back, each containing a small amount of a suspected allergen in a solution. Depending on the individual's history, the test may include as few as six allergens, or as many as eighty. If the patient is allergic to any of the allergens, a raised red spot like a hive, called a wheal and flare will appear at the site after about 20 minutes. Although very rare, systemic reactions (and even fatalities) to skin testing have been reported.
• Intradermal Skin Testing - This test, which is performed by injecting a drop of an allergen extract into the skin, has a very high non-specific reaction rate, but is useful for investigating drug and stinging insect allergy.
• Blood Specific IgE Testing (e.g., ImmunoCAP) - This test measures the amount of IgE in the blood and can identify and quantify the person's specific allergic sensitivities. This approach can be performed in a primary care setting, carries no risk of anaphylaxis, and does not require the discontinuation of any medications (that might interfere with the test results) prior to testing.