Noninhaled intranasal carbon dioxide (CO2) has been shown to be effective for treatment of migraine headache. Migraine headache pathophysiology is associated with release of calcitonin gene-related peptide, also implicated in allergic rhinitis. Intranasal CO2 inhibits the release of calcitonin gene-related peptide.In a single-center RCT, two 60-second intranasal CO 2 treatments resulted in rapid (10 minutes) and sustained (24 hours) relief of seasonal allergic rhinitis symptoms. The authors concluded that, intranasal CO2 has a potential as a safe and effective treatment for seasonal allergic rhinitis.
However, the newer studies, from 2011, were less promising: Intranasal CO2 spray helps allergic rhinitis symptoms but only for 4 hours and at the cost of relatively poor tolerance http://goo.gl/b0wwt
References:
Intranasal noninhaled carbon dioxide for the symptomatic treatment of seasonal allergic rhinitis.
Casale TB, Romero FA, Spierings EL. J Allergy Clin Immunol. Volume 121, Issue 1, Pages 105-109 (January 2008).
Intranasal CO2 spray helps allergic rhinitis symptoms but only for 4 hours and at the cost of relatively poor tolerance http://goo.gl/b0wwt
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Comments from Twitter:
@AllergyNet (Dr John Weiner): Tens of millions of people squirting CO2 into the air? I don't think so @Reuters_Health Can CO2 help with hayfever reut.rs/nmylh5
Treatment Options for Allergic Rhinitis (click to enlarge the image).