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 - (95% confidence interval ( CI ) - to -), MD - (95% CI - to -) and MD - (95% CI - to -) 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 (95% CI to ).
This treatment is sometimes used, mainly in cases where symptoms are severe and not helped by other treatments. It is done using a series of injections of the allergen causing the rhinitis, in increasing quantities. The idea is that your immune system will become desensitised to the allergen. This means that the allergic response that your body mounts when it is exposed to the allergen in the future is reduced, so improving your symptoms. Another technique is being developed which involves placing the allergen under the tongue. However, this may not yet be widely available.