Yes. Here's a personal anecdote to illustrate. Years ago I had dental surgery, and the dentist prescribed a new and very expensive antibiotic for me. I was poor at the time, and paying for that was a serious hardship.

The next day I had a severe allergic reaction to it, and the dentist replaced that prescription with plain old penicillin (which cost me $10 for the complete treatment). I was absolutely furious that he didn't go with the affordable and time-tested treatment first.