Immediately after I was given some shots in the mouth my legs started feeling kind of numb and I began to shake. Almost like I was shivering. I also felt anxiety, but not about the prospect of getting shots, rather, I felt a rush and my heart started beating fast after the injection. I didn't tell the dentist about this. These effects lasted for maybe five minutes or less. Why did this happen? I should note that I did not take an Ativan (anti-anxiety drug for my dental phobia) that day.