on drugs longer than needed

Someone was taking the drug Gaberpentin for pain, but because late putting her repeat prescription, had to ration the ones she had, so was a period of time she didnt take any., and to her complete surprise had no pain at all, so didnt need to take them. This she wouldnt have known, if hadnt had to stop and ration. Interesting stuff. do we just take drug sanyway even if the reason is gone, but we just dont know. And I am sure have looked up Gaberpentin and has some ms related side effects and quite a few at that