Fear of blood: An abnormal and persistent fear of blood. Sufferers of this very common phobia dread the sight of their own blood, the sight of the blood of another person or an animal, and sometimes printed or filmed images of blood or even thoughts of blood. Blood may remind them of their own vulnerability to injury and of the eventuality of death.

Some sufferers of hemophobia experience an increase in blood pressure and heart rate. Other sufferers experience an atypical phobic reaction characterized by a decrease in blood pressure and heart rate, causing paleness and weakness. They may even faint. Those with the latter reaction may develop a new fear: the fear of fainting.

Through the ages, writers have done little to calm the fear of blood. In Homer's Iliad, waterways run red with blood as a wrathful Achilles harvests his crop of Trojans. In Shakespeare's Macbeth, blood becomes a terrifying symbol of guilt to Lady Macbeth, and she washes her hands raw to rid them of blood, real or imagined. In Bram Stoker's Dracula blood becomes the nurture of a vampire.

This fear of blood is termed "hemophobia," a word derived from the Greek "haima" (blood) and "phobos" (fear). Other English words derived from "haima" include "hemodialysis" (a procedure that removes impurities from the blood), "hemoglobin" (a blood component that transports oxygen from the lungs to other parts of the body) and "hemorrhage" (rapid blood loss). Alternate name for hemophobia: hematophobia.