I Gave a Patient the Wrong Medication

I was a frazzled new nurse on a busy, short staffed cardiac stepdown unit. Trying to save time, I pulled patient A and patient B’s medication at the same time and put the meds in two different piles on my WOW. (I think you know where this is going haha)  I wheel into patient A’s room, scan his meds, and all his well. I give him his pills and as he swallowed them it felt like my heart stopped because I realized I gave him patient B’s medications. I didn’t say anything to the patient. I stepped out of the room and confessed to my friend/mentor on the unit.  He went over each patient’s chart with me and double checked allergies.  Turns out the only significant medication was a switched blood pressure pill. Taking the somewhat sketchy advice from my mentor, I didn’t call the doctor, tell the patient, or report myself.  I monitored the patient’s blood pressure more frequently and the patient was fine. Obviously I learned from that mistake and have never made that mistake again!