From local anesthesia 

Text removed from local anesthesia which IMO might be better placed here, please review.  

Generally, a certain risk of local tissue damage is involved when using local anesthetics often and regularly during a longer period at a specific location of your body. For example, the chronic use of topical eye anesthetics in chronic eye pain would almost certainly and relatively quickly lead to serious eye damage (corneal damage).
Before using local anesthetics, chronic local pain should not only carefully be assessed with medical specialists for the local problem (for example an ophtalmologist, dermatologist, dentist or a neurologist/specialist for peripheral nerve blocks), but also by specialists for centrally active pain medication.
 Medical specialists (ophtalmologists, dermatologists, dentists or neurologists for peripheral nerve blocks) for the local problem can assess how big the risk of chronically using local anesthetics at that particular location is.
 In most cases of chronic pain, it is not the peripheral nervous system but the central nervous system that is not able to cope with the pain impulses coming from the location in the peripheral nervous system where the damage that causes the pain is actually located. Therefore, medical specialists for the central nervous system (usually a neurologist or pain specialist) can assess if and what kind of centrally acting medication can or should be taken. Very often, it is less harmful and risky to use centrally active substances (especially when they are only taken in low doses) against chronic pain in the peripheral nerve system than chronically using local anesthetics at a particular location of the body. Relatively risk free, especially when taken in small doses, and at the same time often effective against chronic peripheral pain are antidepressants of the SSRI class and the stronger tricyclic antidepressants like for example amitriptyline. Furthermore, modern anticonvulsants like pregabalin or gabapentin are relatively risk free and at the same time relatively effective against chronic pain, at least when taken in very low or low doses. One of the strongest and more risky options in the reduction of peripheral pain are anticonvulsants like carbamazepine. On the other hand, some other classes of centrally acting substances like for example opioids (they are unfortunately still often used in the treatment of chronic pain, including local pain in the peripheral nerve system) are extremely harmful and should be avoided in the treatment of chronic pain at all costs.