Can you sweat blood?
Yes, you can. Sweating blood was reported by few persons in high
stress situations (fear of death, etc.), and it's proven. But I
don't know exactly why this happens... maybe some cells break in
the inside of those skin channels... of course, nobody sweats blood
for the same purpose you sweat when it's hot!
Sweating blood is known as hematidrosis or
hemohydrosis, and it occurs in persons who undergo or have
gone through high stress levels.