CAPSAICIN USE FOR ORAL PAIN
Alternative Treatments for Facial Neuralgias

Disclaimer. 

The following was excerpted from the article NCI/PDQ Physician Statement: Oral complications secondary to cancer therapy - (Updated 08/96) on the Oncolink website. It is posted here in compliance with the FAIR USE DOCTRINE and is for educational purposes only, not for commercial use.

"It has been suggested that capsaicin preparations may be effective in controlling oral mucositis pain. Capsaicin and its analogues are the active (hot) ingredients in chili peppers that produce burning pain by stimulating polymodal nociceptors, the predominant pain receptors found in skin and mucous membranes. The receptors are described as polymodal because they are multiply sensitive to noxious heat and mechanical and chemical stimuli.[26-28] It has been demonstrated experimentally that after ingesting capsaicin-containing foods or after capsaicin application to the oral mucosa, the severity of pain is directly proportional to the concentration of capsaicin present. After a single exposure, acute burning pain occurs promptly and wanes gradually. If capsaicin exposure is repeated promptly, before the burning sensation from a previous exposure has dissipated, sensitization (i.e., more intense pain) may occur.[29] Conversely, if capsaicin exposure is repeated after the burning sensation from a previous exposure has dissipated, nociceptor desensitization occurs.[30] Capsaicin's clinical potential derives from the fact that it elevates the threshold for pain in areas to which it is applied.[26,27] The pain threshold can be further elevated by gradually increasing the capsaicin concentration in a series of repeated applications.[28] Capsaicin's desensitization effect is generalizable to other painful stimuli as well. When capsaicin is applied to inflamed oral mucosa, mucositis pain diminishes as the burning sensation caused by capsaicin subsides.

"Thus far, capsaicin formulations for intraoral use are investigational. In the United States, 0.025% and 0.075% topical capsaicin lotions and creams are available without a prescription for external use only; none of the commercial products are formulated for use within the oral cavity or on other mucosal surfaces. There exists one case report in which a patient with pain due to post therapeutic neuralgia applied commercially available capsaicin 0.025% cream intraorally. The patient experienced symptomatic improvement within 2 days and pain was abolished after 4 weeks of treatment.[31] In addition, Berger et al. [32] have described an extemporaneous formulation of cayenne pepper candy (taffy). The investigators varied the amount of cayenne pepper in their formulation, permitting them to escalate the capsaicin concentration to which patients were exposed. Patients who became desensitized to a low capsaicin concentration tolerated exposure to higher concentrations more easily. Theoretically, when the concentration of capsaicin is increased to produce burning pain approximately equal to a patient's mucositis pain, mucositis pain may diminish or disappear as the sensation from capsaicin dissipates. All patients reported relief from mucositis pain, and pain was abolished in 2 of 11 patients, with continued use of the candy (4-6 candies over 2-4 days). Two patients discontinued using cayenne pepper candies due to adverse effects.

"Thus far, evidence that capsaicin produces symptomatic relief for mucositis pain is encouraging but limited to anecdotal reports and a small case series. Of no small concern, however, it is not yet known what effects capsaicin may have on compromised human gastrointestinal mucosa at doses and for durations that may be useful in treating mucositis. Further evaluation is certainly warranted; however, clinical evaluation and acceptance among clinicians who lack facilities to extemporaneously prepare capsaicin products will limit its development until a uniformly consistent formulation becomes available."

 26. Jancso N, Jancso-Gabor A, Szolcsanyi J: Direct evidence for neurogenic inflammation and its prevention by denervation and by pretreatment with capsaicin. British Journal of Pharmacology and Chemotherapy 31(1): 138-151, 1967.
27. Szolcsanyi J: A pharmacological approach to elucidation of the role of different nerve fibres and receptor endings in medication of pain. Journal de Physiologie (Paris) 73(3): 251-259, 1977. 
28. Dray A: Mechanism of action of capsaicin-like molecules on sensory neurons. Life Sciences 51: 1759-1765, 1992.
29. Green BG: Evidence that removal of capsaicin accelerates desensitization on the tongue. Neuroscience Letters 150: 44-48, 1993. 
30. Green BG: Temporal characteristics of capsaicin sensitization and desensitization on the tongue. Physiology and Behavior 49(3): 501-505, 1991.
31. Hawk RJ, Millikan LE: Treatment of oral postherpetic neuralgia with topical capsaicin. International Journal of Dermatology 27: 336, 1988.
32. Berger A, Henderson M, Nadoolman W, et al.: Oral capsaicin provides temporary relief for oral mucositis pain secondary to chemotherapy/radiation therapy. Journal of Pain and Symptom Management 10(3): 243-248, 1995.