Allergic rhinitis is a common health problem affecting between 10% and 25% of the population, and its prevalence is increasing. The symptoms include a running or blocked nose, itching and sneezing. Several drug therapies are available including antihistamines and steroids. Capsaicin, which is the pungent component of hot pepper, has also been used. With repeated doses applied topically it may desensitize the lining of the nose and have a therapeutic effect on allergic rhinitis. The review found one small, low quality randomized controlled trial which did not demonstrate a therapeutic effect of capsaicin on allergic rhinitis symptoms. Further trials are needed.
There is insufficient evidence to assess the use of capsaicin in clinical practice.
This is an update of a Cochrane Review first published in The Cochrane Library in Issue 2, 2006.
Allergic rhinitis represents a global health problem. Non-specific nasal hyper-responsiveness is an important feature of allergic and non-allergic rhinitis. This phenomenon is believed to result from the effect of allergic inflammation on the sensory nerves that supply the upper airway mucosa. A pharmacological agent that has proved useful in the investigation of effects of neuronal stimulation is capsaicin, the pungent component of hot pepper. Intranasal capsaicin specifically stimulates afferent nerves consisting mostly of unmyelinated C fibers and some myelinated A-delta fibers. As a result it can trigger central and axonal reflexes, the latter being putatively mediated by the release of neuropeptides. Capsaicin, as a blocking agent of neuropeptides, blocks the axon reflex and may exert a curative effect on allergic rhinitis.
To assess the effectiveness of capsaicin for allergic rhinitis in adults.
We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; mRCT and additional sources for published and unpublished trials. The date of the most recent search was 2 September 2009.
Randomized controlled trials of capsaicin for allergic rhinitis in adults.
Three authors read each paper, blind to its identity. Decisions concerning inclusion were made by simple majority. We all performed quality assessment independently.
One small trial did not find evidence that intranasal capsaicin had a therapeutic effect in allergic rhinitis. A small pharmacological effect on clinical histamine dose response was found. After treatment, leukotriene levels in nasal lavage did not increase in the capsaicin group.