Prescription Marked No Refills

A distraught patient phoned her doctor's office.

"Is it true", the woman wanted to know, "that the medication you prescribed has to be taken for the rest of my life?"

"Yes, I'm afraid so," the doctor told her.

There was a moment of silence before the woman continued:

"I'm wondering, then, just how serious my condition is. This prescription is marked NO REFILLS!"