Capsaicin
"I used capsaicin for relief of neck pain (eventually resolved by surgery) & now for very painful arthritic knees. 



It was very effective for the neck pain AFTER i slowly built up to effective dose.  Currently trying to reach therapeutic level for knees -- slow going due to hot weather & sweating.



Capsaicin can cause very bad burning pain if it gets wet during bathing or sweating before one has built tolerance.  In fact, i swore off it twice due to agonizing burning before learning to manage the early months of use much more carefully & start low & slow (as I'm doing now with knees).  However it's a great pain treatment once you learn to use it carefully & build tolerance.  Wash hands twice or use gloves to avoid possible eye contact!"