<s>[INST] I have been diagnosed after years of mis or not diagnosed with tri-geminal neurolgia. I have been given tegretol-xr 100mg 2 times daily.  The last episode about six months ago it did not help. This time after the first day it seems to be working as the pain is gone. Should I only take this when the episodes start again.  Sometimes I can go for a year or more with none. I dont want to have the liver side effects so only am taking when the pains start again. [/INST] Hi, Thank you for posting your query. Yours is a very good question. Regret only helps relieves the symptom, in this case, pain due to Trigeminal neuralgia. So, it does not make sense to take regret for one year to prevent one episode of pain. So, in your case, you can take it as and when you get the pain. Most people have frequent pain, even on a daily basis, they need to take it every day. Best wishes, Chat Doctor.  </s>