The sight of blood causes many people to get queasy and lightheaded. They may even pass out. The phobia is common enough that it earned a spot in the “Diagnostic and Statistical Manual of Mental Disorders,” psychiatrists’ principal reference book. A physical response to the sight of blood is totally natural, especially for men, says one expert, Steven Lamm, medical director of the Tisch Center for Men’s Health at NYU Langone Medical Center in New York City. Dr. Lamm explains how to trick the body into not feeling squeamish, and why a sweet cup of coffee might be your best friend.

Fight or faint

Seeing blood usually means you or another person is in pain. By reacting, a person “shows empathy, which is a good trait,” says Dr. Lamm, who trains medical students to diagnose and treat patients. “The trick is learning how to condition or compartmentalize your response,” he says.

Feeling queasy is a physiological response to fear, and the related mental and physical cues are likely part of the evolutionary “fight-or-flight” survival mechanism, he says. Inside the body, the blood vessels dilate, blood pressure starts to drop and the heart starts to slow. That’s when “all the blood drains to your legs,” Dr. Lamm says. “Then you get lightheaded and nauseous.”

“By fainting or nearly fainting, your mind is trying to extricate yourself-as in flee-from the situation,” he says.

Women and children

Women tend to be less squeamish than men about blood, especially those who have given birth, he says. Children often have strong physiological reactions to blood, but can be coaxed out of an anxious episode through positive reinforcement. “For kids, we tell them to be tough and then reward them for bravery,” he says.

Repeated exposure by adults and children can reduce one’s reaction to blood. “You are practicing confronting your fear. Through that repetition, the brain becomes less stressed. And seeing blood is definitely stressful,” Dr. Lamm says.

Many methods

Medical students come up with many methods to overcome their squeamishness at seeing bloody wounds and bleeding patients, Dr. Lamm says. Some choose to distract the mind, using techniques like rocking from side to side or running through numbers or times tables. Before seeing blood, they might talk themselves out of any potential anxiety by visualizing in advance what is going to happen. “Even regular people can start to dissociate themselves from the sight of blood this way,” he says. “And eventually you are conditioned not to react.”

A sugary, caffeinated beverage can be a big help before an interaction with blood. The caffeine will slightly raise blood pressure, helping to counteract the body’s own blood-pressure decline. And sugar will prevent the lightheadedness that might have been brought on in part by a hypoglycemic condition, Dr. Lamm says. He recommends when people know they are about to see oozing blood, they should eat food and drink water in advance, since dehydration and low blood sugar can heighten the symptoms and lead to fainting.

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