Nah, no physical danger. You're only dispensing the drugs, you’re not testing them on yourself or anything. If it's busy in the pharmacy, you might accidentally bump into a co-worker and bang heads. That's about the extent of it.
However, you have to be careful that you don't take advantage of your access to pharmaceuticals and develop a dangerous addiction. It is, of course, illegal for you to take anything not prescribed to you by a doctor (not to mention that you'd be stealing), but it may be hard for some to resist the urge. If this sounds like you or you have an addictive personality, best to avoid this career altogether and do something else. No, dealing blackjack in a casino is not what we had in mind.