Stomatodynia is a difficult disease for both patients and clinicians. When 
facing true stomatodynia, i.e., idiopathic burning mouth, patients are offered 
poorly effective treatment. This open study reports the results of local 
application of clonazepam (0.5 or 1 mg) two or three times daily in 25 subjects 
who suffered from idiopathic stomatodynia. At the first evaluation, 4 weeks 
after the beginning of treatment, a visual analogue scale (VAS) that represented 
the intensity of pain decreased significantly from 6.2 +/- 0.3 to 3.0 +/- 0.5. 
At the second evaluation, 3 to 29 months after the first consultation, the VAS 
scores dropped significantly further to 2.6 +/- 0.5. Analysis of the individual 
results showed that 10 patients were totally cured and needed no further 
treatment, 6 patients had no benefit at all, and the remaining 9 patients had 
some improvement but were not considered to be cured since they did not wish to 
stop the treatment. Blood level tests that were performed 1 and 3 hours after 
the topical application revealed the presence of small amounts of the drug (3.3 
ng/mL +/- 0.66 and 3.3 ng/mL +/- 0.52, respectively). The hypothesis that 
clonazepam acts locally to disrupt the neuropathologic mechanism that underlies 
stomatodynia is proposed. The risk factors that are recognized for this 
condition could decrease the density and/or ligand affinity of peripheral 
benzodiazepine receptors. This, in turn, could cause spontaneous pain from the 
tissues concerned.