The symptoms of outdoor allergies are very similar to those of the common cold so it may be difficult to distinguish between the two. A good rule of thumb is when cold-like symptoms last longer than one or two weeks, or if you tend to have frequent cold-like symptoms, you may want to consult your doctor to discuss being tested for allergies. You may also want to consult your doctor about allergies if you notice any of the following:

• You tend to have cold-like symptoms around the same time every year.
• You experience sudden sneezing or upper respiratory congestion and your eyes itch as soon as you go outside, but it tends to get a little better when you go inside. Note, however, that for some people, symptoms may continue to last long after initial exposure.
• Your symptoms are severe and interfere with your daily life.

When you see the doctor about your suspected allergies, he or she will likely give you a physical exam and ask you about your recent history of symptoms as well as your family’s history of allergies and asthma. Giving a complete and thorough history is the most important way to find out if your symptoms may be related to allergies. If the doctor suspects you may have outdoor allergies, he or she may conduct allergy testing or may refer you to a specialist for allergy testing. Allergy testing can tell you exactly what allergens you are allergic to, which may help you avoid them in the future.

Allergy skin tests are usually conducted by an allergy specialist and involve administering a series of possible allergens into scratches made on the arm or back or by injecting them subcutaneously (under the skin). If you are sensitive to a particular allergen, it provokes a small immune response and your skin will become raised and red in the area where it was injected. The size of the raised area determines how sensitive you are to each particular allergen.

In some cases, an allergist may take a blood sample in order to determine the levels of IgE antibodies present in your blood that are directed against specific allergens. The most common such test is called RAST (for radioallergosorbent test). Blood tests are more expensive and less sensitive so they are usually reserved for people in whom skin testing can’t be used, such as those with skin conditions like eczema or those taking medicines that might interfere with the skin test results.