I had an elderly neighbor prescribed this for shingles pain. But if you are concerned about side effects of the medicine, you might look into a different approach for the management of the nerve pain, like acupuncture and suggest your mother in law might try it if she hasn't already. If she doesn't want to be on the medicine, she shouldn't go off it without the knowledge and guidance of her physician on how to do it safely.
You can also call a local pharmacist and ask if a medication is appropriate.
Gabapentin aka neurontin is used for nerve pain... I tried it.
Hiya-
Gabapentin is used often for nerve pain. Another one that is used often is Lyrica. Even some antidepressants are used in pain management.
These are sometimes used along with other medications or by themselves.
If you are concerned about her meds, why don't you ask if she wants someone to go with her to her next appointment.
Horselip