@leigho55, I did find some research on using Qutenza for postherpetic neuralgia that may be helpful. Here is an excerpt from the attached PDF file found using Google Scholar (https://scholar.google.com/).

"A capsaicin 8% patch is approved in the U.S. for use in the treatment of pain associated with
postherpetic neuralgia (Qutenza®, Acorda Therapeutics Inc.). The patch is applied by a
physician for 30-60 minutes per treatment and may provide relief for up to 3 months.30 A
separate Cochrane review (4 studies of PHN and 2 of painful HIV-neuropathy) reported the
patch to be better than control (0.04% capsaicin for blinding).33 The average NNT to feel
"much" or "very much better" was 8.8 and 7.0, respectively, after 6 weeks.33 Serious adverse
effects were no different between the groups, but the safety of long term, repeated application
of high-dose capsaicin is unknown. The patch is not available in Canada and future availability
is uncertain."