Hi, I have a bit of an odd question. I have a tooth infection and was prescribed Amoxicillin (500mg) last month in the ER. It cleared up, but has come back, so I went back today and got a prescription for Penicillin (500mg 2x a day) until I can get to the dentist in a couple weeks. Thing is, last night I took one leftover Amoxicillin caplet, and I'm wondering if it's okay to start on my Penicillin course if there's a chance that the one caplet Amoxicillin is still in my system? I forgot to mention it and ask the ER doc or pharmacist.