I went to a talk given by a professor of pharmacology who studied which herbal remedies work. She did say capzasin works but only if you use a 0.1% cremme applied 4 times a day. Less than that is not a therapuetic dose. She commented the burning pain on initial use is a temporary effect that goes away with regular use.

However, as you found, the initial burning pain can be bad enough for some people it's not worth trying to get to a therapuetic dose.

In the UCSF study, people were given 5% to 10% capzasin with a painkiller for that initial burning pain.

I tried it when I had high hypersentivity (i.e. alodynia) and the initial pain was quite bad and I couldn't tolerate the product. When my hypersentivity is lower and I just have the burning pain from my TOS, I can tolerate the initial burning pain of the capzasin . I can even apply the cremme to a wide area.