Is capsaicin applied into the nose (intranasal) effective in the management of non-allergic rhinitis compared with no therapy, placebo or other topical or systemic medications?
Rhinitis means inflammation of the nose. It affects 30% to 40% of the general population. There are many forms of rhinitis: rhinosinusitis (or simply sinusitis), allergic rhinitis and non-allergic rhinitis. Non-allergic rhinitis is diagnosed in patients who have negative tests for allergies and also do not have sinusitis. The symptoms include congestion of the nose, a blocked or obstructed sensation in the nose that causes difficulty breathing, clear nasal discharge (runny nose), sneezing and nasal itching. There are several subtypes of non-allergic rhinitis: occupational (from exposure to chemicals), smoking, gustatory (related to eating food or drinking fluid), hormonal (from changes in hormone levels in the body), pregnancy, senile or elderly (mostly affecting the older population), medication-induced (for example, from overuse of decongestant nasal sprays) and local allergic (local allergy in the nose, while skin or blood allergy tests are negative). The most common subtype of non-allergic rhinitis is 'idiopathic' or 'vasomotor' rhinitis, which results from imbalance of the neural (nerve) system that manages the function of the nose. The mechanisms of many of these subtypes remain unknown. Non-allergic rhinitis affects about 25% to 50% of patients with rhinitis and is therefore very common.
Capsaicin is the active ingredient of chili peppers. It has medicinal properties and is used elsewhere in medicine, for example for neuralgias (nerve pain) and psoriasis (a skin disease). The side effects of using capsaicin in the nose include irritation, burning, sneezing and coughing, however there are no known long-term side effects of capsaicin use. Capsaicin is given in the form of brief treatments, usually during the same day. It works by down-regulating transient receptor potential vanilloid (TRPV) receptor expression on C-sensory fibres. TRPV represents special ion channels involved in the sensations of pain, cold, hotness, tastes, pressure and vision. C fibres help to conduct some of these sensations. There is ongoing research into the effects of capsaicin on these mechanisms and its clinical uses.
We included four studies involving 302 patients with idiopathic non-allergic rhinitis. All the included studies described patients with moderately severe idiopathic non-allergic rhinitis, who were between the ages of 16 and 65. The studies had a follow-up ranging from four to 38 weeks after treatment.
Individually, the studies reported that the overall function of the nose in patients with non-allergic rhinitis improved when treated with capsaicin compared to placebo. Capsaicin also seems to work better than another common type of nasal medication, budesonide (a steroid). The best knowledge that we have on capsaicin treatment supports giving it five times in one day, and to use doses of at least 4 micrograms in each puff. We could not combine the results together. The included studies did not have sufficient information to allow us to draw a conclusion about side effects. We also wanted to include other outcomes (e.g. quality of life measures, treatment dropouts, endoscopic scores, turbinate or mucosal size, cost of therapy), but none of these were measured or reported in the included studies.
Quality of the evidence
Overall, we judged the quality of the evidence to be of low to moderate quality. The evidence is up to date to June 2015.
Given that many other options do not work well in non-allergic rhinitis, capsaicin is a reasonable option to try under physician supervision.
Capsaicin may be an option in the treatment of idiopathic non-allergic rhinitis. It is given in the form of brief treatments, usually during the same day. It appears to have beneficial effects on overall nasal symptoms up to 36 weeks after treatment, based on a few, small studies (low-quality evidence). Well-conducted randomised controlled trials are required to further advance our understanding of the effectiveness of capsaicin in non-allergic rhinitis, especially in patients with non-allergic rhinitis of different types and severity, and using different methods of capsaicin application.
There are many forms of rhinitis. Patients are diagnosed with non-allergic rhinitis when anatomic, infectious and allergic aetiologies have been excluded. The symptoms, including nasal congestion, blockage or obstruction, clear rhinorrhoea, sneezing and, less frequently, nasal itching, can range from mild to debilitating. It affects between 25% and 50% of patients with rhinitis. Several medications are widely used in the treatment of non-allergic rhinitis, including oral and topical nasal antihistamines, intranasal and (rarely) systemic corticosteroids, and anticholinergics. Capsaicin, the active component of chili peppers, delivered intranasally, is considered a treatment option for non-allergic rhinitis.
To assess the effectiveness of capsaicin in the management of non-allergic rhinitis compared with no therapy, placebo or other topical or systemic medications, or two or more of the above therapies in combination, or different capsaicin regimens.
We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 5); PubMed; EMBASE; CINAHL; Web of Science; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the search was 24 June 2015.
Randomised controlled trials in adult patients with non-allergic rhinitis comparing intranasal capsaicin with no therapy, placebo or other topical or systemic medications, or their combinations.
We used the standard methodological procedures expected by The Cochrane Collaboration.
We included four studies (five publications) involving 302 participants with idiopathic non-allergic rhinitis. All the included studies described patients with moderately severe, idiopathic non-allergic rhinitis who were between the ages of 16 and 65. Studies had follow-up periods ranging from four to 38 weeks. The overall risk of bias in the studies was either high or unclear (two studies had overall high risk of bias, while two others had low to unclear risk of bias). Using the GRADE system we assessed the evidence as being of low to moderate quality. A meta-analysis was not possible, given lack of similarity of the reported outcomes.
Two studies compared capsaicin with placebo. One study reported that capsaicin resulted in an improvement of overall nasal symptoms (a primary outcome) measured on a visual analogue scale (VAS) of 0 to 10. There was a mean difference (MD) of -3.34 (95% confidence interval (CI) -5.24 to -1.44), MD -3.73 (95% CI -5.45 to -2.01) and MD -3.52 (95% CI -5.55 to -1.48) at two, 12 and 36 weeks post-treatment, respectively. Another study reported that, compared to placebo, capsaicin (at 4 µg/puff) was more likely to produce overall symptom resolution (reduction in nasal blockage, sneezing/itching/coughing and nasal secretion measured with a daily record chart) at four weeks post-treatment (a primary outcome). The risk ratio (RR) was 3.17 (95% CI 1.38 to 7.29).
One study compared capsaicin to budesonide (an intranasal corticosteroid). This study found that patients treated with capsaicin had a better overall symptom score compared to those treated with budesonide (MD 2.50, 95% CI 1.06 to 3.94, VAS of 0 to 10). However, there were no differences in the individual symptom scores for headache, postnasal drip, rhinorrhoea, nasal blockage, sneezing and sore throat assessed during the last three days of a four-week treatment.
One study compared two different regimens of capsaicin administration: five treatments in one day versus five treatments given every two to three days during two weeks. Using daily record charts, the study reported significant improvement of individual symptom scores for rhinorrhoea in patients treated five times per day, however numerical data were not presented. There were no improvements in the other outcomes: rhinorrhoea, nasal obstruction, sneezing and overall nasal symptoms, measured on a VAS.
Finally, one of these studies also compared three doses of capsaicin (to placebo). Patients treated with a 1 µg versus 4 µg per puff dose of capsaicin had a worse daily record chart overall symptom score resolution (RR 0.63, 95% CI 0.34 to 1.16).
Only one study attempted to measure adverse effects (a primary outcome), however due to methodological issues with the assessment we are unable to draw any conclusions.
We sought to include other secondary outcomes (e.g. quality of life measures, treatment dropouts, endoscopic scores, turbinate or mucosal size, cost of therapy), but none of these were measured or reported in the included studies.