Will a tetanus shot cause an armpit to fell sore?

A tetanus shot is typically administered in the upper arm, not the armpit. After receiving a tetanus shot, it is common to experience some soreness, redness, and swelling at the injection site. This is a normal reaction and usually resolves within a few days. If you are experiencing severe pain or swelling in your armpit that is not improving after a few days, I recommend you seek medical attention.