Antonyms of prescription:
over-the-counter drug, over-the-counter medicine, nonprescription, over-the-counter.
Examples of usage:
  1. I said the matter required careful thinking over, and suggested that I should send him a prescription a little later.
    "The Queen of Hearts", Wilkie Collins Last Updated: January 3, 2009.
  2. " As I have strong reasons to remain alive, I shan't adopt your prescription, Dr. Greeby," said Lambert, dryly.
    "Red Money", Fergus Hume.
  3. I'll tell the doctor how well his prescription worked.
    "Clover and Blue Grass", Eliza Calvert Hall.