Lidocaine patches can drop pains by 1.5-2 points on the pains scale – which is about as much as you get from painkillers.
Patient Prefer Adherence. 2013 Jun 18;7:551-7.
Influence of anatomic location of lidocaine patch 5% on effectiveness and tolerability for postherpetic neuralgia.
Nalamachu S, Wieman M, Bednarek L, Chitra S.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693920/pdf/ppa-7-551.pdf
- Decrease is VAS was 1.5 – 2/1- points
- patches on scalp were a problem – 5-10 % lidocaine in uremol lotion would be easier
addendum:
Minerva Med. 2013 Dec;104(6):631-637.
Experience with 5% lidocaine medicated plaster in the treatment of localized neuropathic pain.
Fogliardi A, Brunori C.
http://www.ncbi.nlm.nih.gov/pubmed/24316916
for more localized neuropathic pain, this group got a 64% reduction in pain which equated to 2.2 reduction on VAS scale
No difference in effectiveness re post herpetic vs non-post herpetic