Hi, post herpetic neuralgia is often treated with
lidocaine patches, drugs like amitryptiline, gabapentin, steroids etc but in some of the cases pain last for quite a long time.
"A randomized controlled trial found that amitryptyline 25 mg per night for 90 days starting with two days of onset of rash can reduce the inicidence of postherpetic neuralgia from 35% to 16%". Taken from website http://en.wikipedia.