Blood-injury phobia: a review.

Natural human uneasiness about blood, injury, or deformity sometimes becomes a specific phobia, which can lead to serious disability if vital medical procedures are refused. Blood-injury phobia usually starts in childhood and is often familial. Unlike other phobic cues, which cause persistent tachycardia, blood-injury phobic cues evoke an initial rise in heart rate followed by vasovagal bradycardia and, frequently, syncope. Although blood-injury phobia may have an evolutionary, genetic, and physiological basis, it can be treated effectively by exposure. The tendency to faint early in exposure therapy can be reduced by lying down, tensing the muscles, or inducing anger.