The diagnosis of rhinitis is based on the symptoms of the patient, combined with a physical examination. The cause of such rhinitis (allergy, infections,…) may be suspected and may need to be confirmed.

The diagnosis of allergic rhinitis is confirmed by proving sensitivity to certain allergen in allergy testing, typically in a skin prick test, and by proving specific antibody IgE in patient's serum.

Diagnosis of non-allergic-non-infectious rhinitis is made by exclusion of allergies and other causes. Excessive response to triggers may be tested in a provocation test, if the diagnosis is not clear.

Physical examination will include anterior rhinoscopy or nasal endoscopy by which the physician will be able to see the inside of the nose in order to ascertain if the mucosa is inflamed, the presence of polyps or other abnormalities.

In some cases, more sophisticated techniques, such as rhinomanometry or acoustic rhinometry may be necessary, sometimes after a challenge test. Ocasionally a CT-scan may be performed to confirm the presence of related conditions such as sinusitis.