Nonallergic rhinitis is diagnosed based on your symptoms and ruling out other causes, especially allergies. Your doctor will perform a physical examination and ask questions about your symptoms.
He or she may also recommend certain tests. There are no specific, definite tests used to diagnose nonallergic rhinitis. Your doctor is likely to conclude your symptoms are caused by nonallergic rhinitis if you have nasal congestion, a runny nose or postnasal drip, and tests for other conditions don't reveal an underlying cause such as allergies or a sinus problem.
In some cases, your doctor may have you try a medication and see whether your symptoms improve.
Ruling out an allergic cause
In many cases, rhinitis is caused by an allergic reaction. The only way to be sure rhinitis isn't caused by allergies is through allergy testing, which may involve skin or blood tests.
- Skin test. To find out whether your symptoms might be caused by a certain allergen, your skin is pricked and exposed to small amounts of common airborne allergens, such as dust mites, mold, pollen, cat and dog dander. If you're allergic to a particular allergen, you'll likely develop a raised bump (hive) at the test location on your skin. If you're not allergic to any of the substances, your skin looks normal.
- Blood test. A blood test can measure your immune system's response to common allergens by measuring the amount of certain antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to specific allergens.
In some cases, rhinitis may be caused by both allergic and nonallergic causes.
Ruling out sinus problems
Your doctor will also want to be sure your symptoms aren't caused by a sinus problem related to a deviated septum or nasal polyps. If your doctor suspects a sinus problem may be causing your symptoms, you may need an imaging test to view your sinuses.
- Nasal endoscopy. This test involves looking at the inside of your nasal passages. This is done with a thin, fiber-optic viewing instrument called an endoscope. Your doctor will pass the fiber-optic endoscope through your nostrils to examine your nasal passages and sinuses.
- Computerized tomography (CT) scan. This procedure is a computerized X-ray technique that produces images of your sinuses that are more detailed than those produced by conventional X-ray exams.