Yes, you should always try to treat pain. Just do it with a thoughtful approach.
It's important to know what the pt's history is, and what the plan of care is. If the patient is supposed to go home tomorrow (presumably on po pain meds) and you've given four doses of IV pain meds, that's no good and you need to explore this more. The po pain meds may not be cutting it, the pt may be playing you for the IV meds, or you may not be giving the best med for the pain. Sure, IV fentanyl works fast, but it doesn't last more than 45 minutes. Those two percocet may not provide instant relief, but it provides LONGER relief, and it may be more appropriate.
I've had pts request the IV pain meds over po, and when we've discussed it, it's because they want to sleep. Well, I've something else that can help with that, and will be more appropriate. Or they just think that IV is always better. No, no it's not. That's why you're waking up ever 2 hours in excruciating pain, because your IV fentanyl isn't providing you with long term relief. You're pain is a 6? We're going to be doing some po meds.
Some pts just want the instant relief (understandably). But they don't have that option at home, and they need to work on finding what will work for them before discharge, particularly if they're going home on a combination of medication (muscle relaxant, narcotic, etc).
If we're in the early stages of pain control, I'm typically not worried about iv vs po, but I always choose po first unless the pain is terribly acute and we've been treating exclusively with iv, there is nausea or there isn't any po ordered. I do always discuss with the pt that the goal will be to go to po, so they know what to expect. I always make sure they understand that po provides longer relief, and that it is also what they will be going home on. They also need to understand that they shouldn't wait until their pain is at an 8 or 9 to ask for the meds.
Another thought: always consider the non-narcotics. We have some nurses who give a narc for EVERYTHING. Pt has a headache? Give lortab. Pt feels achy because of fever? Lortab, dilaudid, or maybe some iv morphine. HELLO! What about that plain old tylenol or ibuprofen? Just because those aren't the big guns doesn't mean they won't provide adequate pain control.
And while I'm on a pain control rant, toradol is WAY underused as a pain medication. I've seen plenty of patients c/o pain uncontrolled by a pca of dilaudid, morphine, or fentanyl get better pain control with intermittent prn iv or po narcs and scheduled toradol. Particularly pts with some sort of abscess or soft tissue pain (peritonsillar abscess comes to mind).
Sorry, I know this is a disorganized post. Mainly my point is, be thoughtful of the entire scheme of things when you are giving prn meds. What is the pt's history, what do they take at home, where are they in the discharge process, what are they taking the pain meds for, what is the most appropriate medication for their overall situation, and what does the physician plan to do with them tomorrow? Do they really need that much prn pain meds? Maybe their scheduled pain meds need to be adjusted, maybe the type of prn pain meds need to be adjusted (lortab 7.5 instead of lortab 5, for example), or maybe we aren't giving them what they take at home, so of course they need a lot of prn pain meds. Oftentimes you will need to consult with the physician, and don't be afraid to do that.