What is Capsaicin
Capsaicin, the substance that makes chile peppers so hot, has been found to reduce pain in arthritis patients when topically applied as a cream repeatedly over several weeks.  Capsaicin cream, which comes in two strengths, .025 % and .075%, is also used to treat the neuropathic pain of postherpetic neuralgia.  It has been used to treat nerve pain inside the mouth, for patients with painful sores from cancer therapy.   A commercial preparation of capsaicin is called "Zostrix".

How Does it Work?
Researchers have found that capsaicin appears to work by "reducing substance P which is found at nerve endings and is involved in transmitting the pain signal to the brain." Clinical studies are emerging which indicate capsaicin cream is more effective than placebos in treating post-surgical neuropathic pain.  However, for TN, ATN, and ATFP, this treatment should presently be considered "under investigation" or "experimental."

For a more in-depth medical description of the uses of capsaisin in treating oral pain, please select: Capsaicin Use for Oral Pain  which has references to several medical journals. One important observation from the article concludes that:

If capsaicin is reapplied after the burning sensation from a previous application has stopped, desensitization  (less sensitivity to pain) occurs.  However, if capsaicin is reapplied before the burning sensation is gone,  sensitization (more sensitivity to pain) might occur.

 It appears that capsaicin works by elevating the threshold for pain (the level when pain is first felt) in the area where it's applied.  The pain threshold can be further elevated by gradually increasing the capsaicin concentration in a series of repeated applications.

Capsaicin and Trigeminal Neuralgia
Capsaicin is not considered a standard treatment for Trigeminal Neuralgia although at least one article in the literature indicates that it may be useful in treating trigeminal neuralgia.  See Science/Health Abstracts Vol. 11, No. 5.  Another article published in the Journal of Orofacial Pain shows that using capsaicin to treat traumatic injury to the trigeminal nerve can result in significant long term pain reduction  (You might have to join Medscape.com in order to access this article in the Journal of Orofacial Pain.  There is no fee for joining).
 
Tips on Using Capsaicin
"Capsaicin usually burns when first applied. It sometimes takes more than a day or two for the effect to kick in, which is when the burning sensation stops. So spending a little more time building up a tolerance to the burning sensation might be one way to make the discomfort a bit more bearable.... It takes something with true detergent action to get this stuff off your skin -- a mild baby shampoo or dish liquid is your best bet -- and a wipe-down with rubbing alcohol won't hurt either. But if you can tolerate it on your skin for at least 15 minutes (so say the package inserts) you will get the benefit even if you have to wash it off later." Source: Anonymous.

Capsaicin is available as a cream or a gel. Researchers at Yale University School of Medicine have devised a candy (butterscotch taffy) with  capsaicin to ease mouth sores caused by chemotherapy  in cancer patients.  The sugar in the candy inhibits the burn of capsaicin in the mouth.  Theoretically, Capsaicin candy could be useful in treating oral neuralgias but there is no supporting medical literature at this time.

For more information see:  Informal Guidelines on using Capsaicin Cream to Treat Facial Pain.

A Note of Caution
At least one article in the scientific literature indicates that there have been no large scale studies of long term effects of capsaicin in the digestive tract of patients whose health has been compromised by surgery or long term neuropathy.  An article summarized in Science/Health Abstracts Vol. 5, No. 3,  indicates that capsaicin can have significant toxic effects within the body.

More information on Capsaicin:

Update on Zostrix (Capsaicin Cream)

  Capsaicin Cream for Surgical Neuropathic Pain

  An In-Depth Patient Experience Using Zostrix

  Hot Pepper Candy Found to Help Chemotherapy Effects.

  Recipe for Hot Pepper Candy

Scientific information on Chile pepper

  What makes peppers hot

  Hot and Spicy Facts about Chile Peppers. Not very medical, but fun nevertheless

Informal Information

Positive Experiences
	[Hot peppers]: "I get some relief for a while if I eat really hot peppers." Source: Anonymous.
	Atypical Facial Pain - "I've been using capsaicin with a dental splint off and on for over a year to treat atypical facial pain. It always relieves the deepest pain after 2-3 applications. Source: Anonymous.
	Trigeminal Neuralgia - "I consider Zostrix to have cured my tic doloroux or whatever name you care to give it. I don't use  the word cure lightly, however, in my case I believe it applies." - Source: Anonymous.
	Glossopharyngeal Neuralgia and Trigeminal Neuralgia - "My experience with cayenne has been somewhat successful. i have been taking cayenne capsules 4 times x 2 daily with food since December and my attacks have been lessened by more than 80%. I can't complain about that. it works for me. "  Source: Anonymous.
	Trigeminal Neuralgia - "I was in the midst of my longest attack ever--five weeks.  I was desperate, grasping at straws.  I bought a tube of Capsaicin cream (in the .05% strength).  The pain lessened with the first application!  Three hours later, after the second application, the pain was GONE.  I have been using it ever since--four applications per day.  I have had NO PAIN.  I can't believe it...but it's true!  I hope everyone will try it--I read a study that said it worked for about half of the TN sufferers who tried it!  Lucky 50%.  I hope you fall into that category!"   Source:  Anonymous
Negative Experiences
	[Hot peppers]:"All I get is a burning mouth. Just more pain." Source: Anonymous.
Mixed Experiences
	It seemed to work during my first attack of this, but now I'm thinking that maybe the sensations just went away on their own, because it doesn't seem to work anymore." Source: "Janine"