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Swoon at the Sight of Blood?

Why the sight of blood might make you faint -- and what you can do about it.
WebMD Magazine - Feature

I didn’t expect to faint at the sight of my son’s blood. As a mother, my job is to nurse boo-boos -- and when when my son came to me after smashing his thumb a few months ago, I prepared to do my best Florence Nightingale. Then I saw the blood.

The room began to spin. I broke out in a cold sweat. I felt all the color drain from my face. After yelling upstairs to my husband to take over, I slid to the kitchen floor.

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Psychologists don’t know exactly why up to 15% of us experience the plunge in blood pressure that causes us to faint whenever we see blood. One theory is that the phenomenon -- officially termed “blood-injury phobia” -- is an evolutionary mechanism.

“The idea is that back in time, when someone was coming at someone else with a sharp stick or rock, a kind of genetic variation allowed certain people to faint in response,” explains Tyler C. Ralston, PsyD, a clinical psychologist in Honolulu, who treats people with blood-injury phobias. Warriors who fainted looked dead and were passed over during battle. The blood pressure drop also might have helped those who were wounded avoid bleeding to death. Survivors then passed on the “fainting” gene.

Treating blood-injury phobia

And while this might have been helpful to our ancestors, it can be absolutely debilitating for people who can’t make it through a simple blood test.

Fortunately, psychologists have devised ways to treat the fear, so if you’re trouble staying upright at the sight of blood, try to find a psychologist trained in treating phobias. For a referral, check with the Association for Behavioral and Cognitive Therapies ( or the Anxiety Disorders Association of America ( The therapist may be able to give you relaxation training (progressively relaxing the muscles of the body), which can be helpful for blood phobia.

The technique that appears most effective is called applied tension, developed by Swedish psychologist Lars-Göran Öst, which works best when coupled with a self-exposure program.

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