Why do Tetanus Shots Hurt?

Tetanus shots don’t hurt as much now as they did years ago. Before they would give you the injection with a 4 gauge needle which is really big. Now they use a much smaller needle for the injection, around 18 gauges and sometimes even a 20 gauge which is even smaller. You will still have some soreness because the injection is down in your muscle which causes pressure and soreness in the spot for a little while.