Scientific American puts it best.

How bad does getting punched in the face hurt. You can feel when its getting better as just moving the jaw muscles will probably tell you how painful it is. Face pain is a burning or achy feeling in any part of your face mouth or eyes. Infectious causes of face pain include the following.

Beginning with the obvious it hurts to get punched in the face. Teary eyes and bloody noses are not uncommon. Ones nose particularly stings quite a bit when you get popped there.

Many bacterial viruses can affect parts of the head such as the teeth and sinuses and indirectly cause facial pain symptoms. One cause of cheekbone pain is trigeminal neuralgia a major nerve pain disorder. But theres more of a mental and emotional shock.

If the motion of your head halts abruptly inertia forces your brain forward. Ditto ribs gut and ears. A punch to the head does to the brain what a car wreck does to passengers.

I keep getting a bad pain that shoots to the top of my head. More importantly for the boxer example is that they are trained to continue to return to guard position after taking a punch. Fever chills swelling on one side of the face pain on one side of the face swollen jaw.

A punch in the face hurts anyway. It hurts so bad now. When you get punched in the face hard enough you can never ever move on.