Herpes zoster is not only a painful disorder but in some individuals it also causes a residual complication known as post herpetic neuralgia. Post herpetic neuralgia is sequelae of shingles and occurs in about 20% of individuals. Once the shingles have resolved, the individual continues to have ongoing pain in the same area. In some cases, this pain goes on for a few months and in some rare cases, it goes on forever.
The exact reason why post herpetic neuralgia occurs is not known but believed to be due aberrant signals in the nerves which continue to amplify the pain signals. The area of shingles becomes extremely hypersensitive such that even the slightest touch can cause severe pain or a burning sensation.
In severe cases, some individuals can't ever wear clothing over the site and even a gust of wind can set off the pain.
The treatment of post herpetic neuralgia is not satisfactory; no one individual responds to the same treatment and the response is variable.
Antidepressants: The tricyclic antidepressants have been used widely to treat the pain. These medications do not work immediately and may take a few days to weeks to completely relieve the pain. Besides the pain the medications also diminish the anxiety and provide good sleep. The tricyclic are excellent at pain relief but only work in about 70% of individuals.
Anticonvulsants: In some cases, anti convulsants like carbamezepine may also be effective in the treatment of resistant cases of post herpetic neuralgia.
Pain medications: Unfortunately the routine pain medications including narcotics do not provide much relief from the pain in all individuals.
Capsaicin cream: A pain medication derived from hot peppers called capsaicin has showed some success in treating a few patients. This medication can be applied topically.
Local anesthetic: Sometimes individuals have used topical anesthetics to control the pain. This does help reduce the pain but the duration of pain relief is short.
In general, the best treatment of post herpetic neuralgia is a combination of pain medications and a tricyclic anti depressant.