Medical and Personal History

To determine whether allergies are triggering rhinitis, the physician will ask a number of questions, including whether a family history of allergies is present, a history of medical problems, any medications the patient is taking, if the patient owns pets, and time of day and year of allergy attacks. The timing of symptoms helps the physician make a diagnosis. Rhinitis that appears seasonally is almost always due to pollens and outdoor allergens. If symptoms occur throughout the year, the physician will suspect perennial allergic or non-allergic rhinitis.

Physical Examination

The physician will usually examine the inside of the nose with an instrument called a speculum. This is a painless examination and allows the doctor to check for redness and other signs of inflammation. The doctor will also usually check the eyes, ears, and chest.

Allergy Skin Tests

A skin test is a simple method for detecting common allergens in people who are candidates for allergy shots (immunotherapy). Those who are not candidates include children under seven years old. Small amounts of suspected allergens are applied to the skin with a needle prick. A new intradermal test that works by injecting a drop of the allergen into the skin may be more sensitive than the standard puncture test. If an allergy is present, a hive, a swollen reddened area, forms within about 20 minutes. Patients should not take antihistamines for at least 12 hours before the test; otherwise an allergic reaction may not show up. About 15% to 20% of people may have a reaction without actually having an allergy. Skin tests are rarely needed to diagnose mild seasonal allergic rhinitis, since the cause is usually obvious. Patients may be tested for up to 80 allergens. Testing for hundreds of allergens is useless because, at that point, the skin may react to everything.

Laboratory Tests

The physician may take a nasal smear. The nasal secretion is examined microscopically for factors that might indicate a cause, such as increased numbers of white blood cells, indicating infection, or high counts of eosinophils. (High eosinophil counts indicate an allergic condition, but low counts do not rule out allergic rhinitis.) Blood tests for IgE immunoglobulin production may also be performed. One called the Radioallergosorbent Test (RAST) is used to detect high levels of IgE in response to particular allergens. The test is expensive, however. Blood tests for IgE are not always accurate, since some patients may have allergies and no increased levels. They should only be performed on patients who cannot undergo skin testing or when skin test results are uncertain.

Imaging Tests

In people with chronic rhinitis, the physician may also check for sinusitis. Imaging tests may be useful if other tests are ambiguous. A test called transillumination, in which a physician shines a bright light against the patient's cheek or forehead, is an inexpensive method for checking for abnormalities in the sinus cavities, although not highly accurate. X-rays and CT scans may be useful for some cases of sinusitis.