Background: Burning mouth syndrome (BMS) is a major diagnostic and therapeutic problem. Systemic and topical treatments (capsaicin, lidocaine, anti-histamines, sucralfate and benzydiamine) have been tried, but they appear to be inadequate. Topical capsaicin is bitter, may cause burning and has low therapeutic efficacy. We hypothesized that systemic administration of capsaicin could reduce the limitations of topical administration and have better therapeutic efficacy; this hypothesis was tested in a controlled trial.
Methods: Systemic oral capsaicin 0.25% was used for patients with BMS, recruited in our single centre. After the diagnosis of BMS, patients were dentally and medically examined. They were alternatively assigned to treatment with capsaicin or to a shape/smell/taste/color matched placebo. The severity of symptoms was scored at trial entry and 30 days thereafter by investigators who were unaware of the assigned intervention. The visual analogical scale (VAS) measure was used to score the severity of pain, and results for the treated and untreated groups were compared by Fisher's exact test. Analysis was performed by intention-to-treat. Statistical significance was considered for values of P < 0.05. Data are expressed as mean ± SD.
Results: Fifty patients were enrolled (25 assigned to systemic capsaicin and 25 to placebo). The VAS score was significantly lower in treated patients (5.84 ± 1.17) as compared to the placebo-control group (6.24 ± 0.96). The use of systemic capsaicin implied significant gastric toxicity (referred gastric pain) with eight cases (32%) documented in the treatment group as compared to zero cases (0%) in the placebo control group.
Conclusion: Systemic capsaicin is therapeutically effective for the short-term treatment of BMS but major gastrointestinal side-effects may threaten its large-scale, long-term use. This preliminary study suggests that more, adequately powered, randomized controlled trials are necessary and worthy to come to a definitive assessment of this matter.