A doctor put in an order for 1 inch of nitroglycerin paste. I was a new nurse and have never given that before. I somehow thought that I could visually measure 1 inch of paste when I squeezed it on the patient’s chest and rubbed it in with my glove. The patient’s blood pressure was in the 160s systolically before the nitro paste, then 5 minutes after it was in the low 100s systolically. My coworker went to check on the patient and then came back and asked me where the nitroglycerin paper was. I was so confused and told her how I just squeezed out about an inch of nitro paste and rubbed it in. She went back to the patient and cleaned his chest off with soap and water. She brought me to the pyxis, showed me the nitroglycerin paper in the same cubby as the nitro paste and showed me how you squeeze it on the paper that has the measurements on it. I was so embarrassed and was struggling to hold back tears. The patient’s blood pressure remained stable and I just let the doctor know that I removed the nitro paste because his blood pressure dropped which was fine. Luckily my coworker was understanding and told me to always ask questions if I have never given a certain medication before. I don’t know why I didn’t and I still beat myself up about it years later. Always ask questions; you’re smarter if you do.