Capsaicin is a TRPV1 receptor agonist. Therefore it agonizes or potentiates the effect of the TRPV1 receptors located in your skin. This receptor's functions are to detect and regulate body temperature. In addition, the receptor also provides us with the detection of hot and cold sensations ie scalding heat and pain. So what does this mean pertaining to capsaicin and pain control?
When capsaicin is applied to our skin, it depolarizes the above receptor and gradually desensitizes our sensory nerves with each repeat application. Over time (up to 12 weeks) capsaicin is able to modulate and inhibit a large portion of pain transmission. Application directions need to be diligently adhered to for capsaicin to work. One single application will not change your pain. As stated above, repeat applications are 100% necessary and you may not notice much at all for the first 6 weeks.
Standard over the counter menthol-containing creams like icy hot, tiger balm, or biofreeze are only mildly helpful and are in a totally different league in comparison to capsaicin. The beauty of capsaicin is that it has the highest (category 1) evidence and proven success with a wide variety of painful conditions. Some examples are the rash and pain after shingles (PHN), complex regional pain syndrome (CRPS/RSD), sciatica, diabetic neuropathy, and even small or large joint pains. It is important to keep in mind that the sooner capsaicin is applied, the greater its benefits recorded.
Capsaicin is available in a few convenient, OTC formulations however , for moderate to severe pain, prescription strengths are often required. There are topical agents for the more mobile body areas as well as capsaicin patches that may be applied by a family member for hard to the difficult to reach places. A one-time application of a highly concentrated (8%) capsaicin patch (for 30, 60, or 120 minutes) is even available. This is considered extremely efficacious and safe however this typically requires the patient to be anesthetized as it will most certainly cause increase temporary, skin site irritation.