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In someone with recurrent sneezing and congestion, that would suggest inflammation of the nose, also called rhinitis. Certainly allergies are a common cause of rhinitis, but there are several causes of non-allergic rhinitis, including responding to environmental conditions, irritating stimuli, certain foods, or emotional stresses. Non-allergic rhinitis can also be exacerbated by alcohol intake or the use of non-steroidal anti-inflammatory medicines, such as ibuprofen or naproxen, although the substances to which an individual can be sensitive can be quite variable. Keeping a diary may help to identify any specific stimuli that precipitates his symptoms.
For treatment, if a specific stimulus can be identified and avoided, that would be fine, but it is frequently not practical. Non-allergic rhinitis typically does not respond well to oral antihistamines, but it does respond better to nose sprays that treat inflammation, particularly steroid nasal sprays. Steroid nasals sprays, though, frequently do not work immediately, so are usually more effective when used regularly for prevention of symptoms than only using the spray when he starts having symptoms.
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