Nosebleeds (3.5e Trait)
From D&D Wiki
Under certain conditions your character gets really bad nosebleeds.
Prerequisite: Must have blood or something of the like.
Benefit: Character may receive +2 constitution or a bonus feat.
Drawback: When your DM finds it appropriate such as a blow to the face, higher altitudes than the character is used to, or highly stressful situations a character with this trait receives either -2 HP per round due to bleeding or a -2 on all attacks, saves, skill checks, and AC from leaning their head back to try to keep it from bleeding too bad. Bleeding must be stopped with a heal DC of 15 (If said character with nosebleed is trying to do this him/herself he/she must make a concentration check first with the possible - 2 penalty). If the situation has not been solved in 1d10 rounds the nosebleed will start again.
Normal: Most characters will not have nosebleeds as easy.