Diagnosis:

To determine the cause of allergic rhinitis, the doctor will ask a number of questions about:

• Time of day and year of rhinitis episodes. Rhinitis that appears seasonally is typically due to pollens and outdoor allergens. If symptoms occur throughout the year, the doctor will suspect perennial allergic or non-allergic rhinitis.
• Family history of allergies.
• History of medical problems.
• In women, if they are pregnant or taking drugs that contain estrogen (oral contraceptives, hormone replacement therapy).
• Use of other medications including decongestants, which can cause a rebound effect.
• Pets.
• Any additional unusual symptoms. As examples, bloody nasal discharge and obstruction in only one nasal passage could suggest a tumor. Fatigue, sensitivity to cold, weight gain, and depression may be signs of hypothyroidism.

Physical Examination

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

Possible physical findings may include:

• Redness and swelling of the eyes
• Swollen mucus membranes in the nose
• Swollen nasal turbinates or nasal polyps
• Evidence of fluid behind eardrum
• Skin rashes
• Wheezing

Allergy Skin Tests

A skin test is a simple method for detecting common allergens. Patients are usually tested for a panel of common allergens. Skin tests are rarely needed to diagnose mild seasonal allergic rhinitis, since the cause is usually obvious. The skin test is not appropriate for children younger than age 3.

The procedure is as follows:

• Patients should not take antihistamines for at least 12 - 72 hours before the test. Otherwise an allergic reaction may not show up.
• Small amounts of suspected allergens are applied to the skin with a needle prick or scratch or are injected a few cells deep into the skin. The injection test may be more sensitive than the standard prick test.
• If an allergy is present, a hive (a swollen reddened area) forms within about 20 minutes.

The test is not completely accurate. In most situations, before testing occurs, patients will have tried to avoid any of their known allergens, as well as tried medications, often including nasal corticosteroid sprays. However, patients with more severe symptoms, particularly those with asthma, significant eczema, or nasal polyps, may benefit from earlier skin testing.

Laboratory Tests

Nasal Smear. The doctor 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.

Tests for IgE. Blood tests for IgE immunoglobulin production may also be performed. One test is called the radioallergosorbent Test (RAST), used to detect increased levels of allergen-specific IgE in response to particular allergens. Blood tests for IgE may be less accurate than skin tests. They should be performed only on patients who cannot undergo skin testing or when skin test results are uncertain.

Imaging Tests

In people with chronic rhinitis, the doctor may also check for sinusitis. Imaging tests may be useful if other tests are ambiguous. CT scans may be useful for some cases of suspected sinusitis or sinus polyps.

Nasal Endoscopy

In certain cases of chronic or unresponsive seasonal rhinitis, a doctor may use endoscopy to examine for any irregularities in the nose structure. Endoscopy uses a tube inserted through the nose that contains a miniature camera to view the passageways.