Your doctor can usually diagnose allergic rhinitis by asking you questions about your symptoms, your activities, and your home life, and examining you. You may need further testing if:

• You and your doctor need to find out exactly what things you are allergic to so that you can take steps to avoid them.
• Treatment is not helping your symptoms.
• You have severe symptoms.
• You are considering allergy shots (immunotherapy).

In these situations, your doctor may suggest:

• Allergy tests. These include:
  • Skin tests. Your doctor will put a liquid containing an allergen on the top layer of your skin and then prick your skin. If the skin reacts with a raised itchy area (called a wheal), it usually means that you are allergic to that allergen. Skin tests are fast, simple, and relatively safe, but results can be false-positive. This means that you do not have an allergy even though results say that you do. If you are very allergic, you cannot have skin testing.
  • Enzyme-linked immunosorbent assay (ELISA, EIA). It measures the blood level of immunoglobulin E (IgE) antibodies that the body may make in response to certain allergens. IgE levels are often higher in people who have allergies or asthma. ELISA may be done instead of or along with a skin test.
• Nasal cytology (nasal smear) testing. This measures eosinophils, a type of white blood cell that may be in the nasal drainage of people who have allergies. Your doctor may use this test to confirm a diagnosis of allergic rhinitis.

Accurate diagnosis of allergic rhinitis is important because many problems have similar symptoms (such as upper respiratory tract infections). Finding what causes your symptoms can help your doctor find the best treatment for you. Your doctor can also see if you have complications, such as sinusitis or asthma.

If your doctor thinks that you have allergic rhinitis, and there are no signs of complications, he or she may decide to treat your symptoms without doing lab tests and then check your symptoms again later.

Other tests for allergies

In most cases, you do not need testing. But your doctor may suggest some tests to eliminate other conditions as the cause of your symptoms. These tests include:

• Imaging tests. Imaging tests of the sinuses, such as X-rays, CT scans, and MRIs, cannot diagnose allergic rhinitis directly. But they can find other diseases, such as a sinus infection (sinusitis), chronic inflammation (thickening) of the sinus lining (often seen in people with asthma), structural defects of the nose, or, in rare cases, cancer.
• Rhinoscopy or nasal endoscopy. In rhinoscopy, your doctor uses a tool called a rhinoscope to see inside the nasal cavity. A nasal endoscopy looks inside the nasal passage with a lighted, flexible tube. Both of these tests look for nasal polyps and other problems that may block the nasal cavity.
• Mucociliary clearance testing. Doctors use mucociliary clearance testing to check for abnormal cilia in people who have very thick nasal discharge. Cilia are tiny hairs on the lining of the nasal passages that beat back and forth to remove particles from the nose. Certain rare diseases can cause problems in the cilia, leading to more nasal secretions.