Fainting and low pain tolerance

Dear Alice,

If I get hurt really sharply or suddenly, I end up passing out. This has happened once when I slammed my finger in a doorway, once when I bashed my elbow on the shower wall, once when my finger was held in an awkward, painful position, and once when I got a flu shot. Why do I pass out like this, and why do I have such low pain tolerance?

Dear Reader,

Ouch! Looks like you’ve acquired quite a few bumps and bruises! While unpleasant, a few fainting spells over a lifetime is fairly common among healthy people. In most cases, fainting is the body’s typical response to a sudden, temporary drop in blood pressure and heart rate. One minor cause is a condition called vasovagal syncope, in which the vagus nerve that regulates blood pressure and heart rate gets overstimulated and responds to triggers more easily. To answer your second question, while each person has a different level of pain tolerance, there’s been no conclusive scientific evidence to suggest that fainting is related to an individual’s pain threshold. While fainting isn’t usually a cause for alarm, in some cases it can be indicative of a more serious condition, such as a heart or brain disorder. Getting evaluated by a health care provider is the best way to figure out the source of fainting and to get connected to further medical care, if needed.

Fainting is a fairly common reaction to the type of pain you’ve described. In fact, some neurologists suggest that fainting is the body’s way of protecting itself after an injury to reduce blood loss. When you experience sudden pain, your heart rate and blood pressure can rapidly decrease, which affects the amount of blood flowing to your brain. This stress on the body, primarily the sudden loss of blood, can result in fainting or a temporary loss of consciousness. Typical triggers of fainting include:

  • Standing up too quickly or standing for a long period of time
  • Being overheated
  • Not eating or drinking enough
  • Seeing blood
  • Having blood drawn or getting an injection
  • Experiencing intense emotions (anger, sadness, etc.)
  • Being in severe pain
  • Consuming excess alcohol or drugs

Adapted from American Academy of Family Physicians and Mayo Clinic.

When it comes to pain, the jury is still out on why pain tolerance varies from person to person. However, some studies suggest that there might be an underlying genetic component that enables some people to withstand more pain than others. All that said, while an unexpected finger jam or elbow bash may be unavoidable at times, there are some other symptoms to look out for that may signal the onset of a fainting spell:

  • Feeling lightheaded or warm
  • Having blurry or tunnel vision
  • Experiencing nausea
  • Looking pale
  • Breaking a cold sweat

Adapted from Mayo Clinic.

If you start to notice some of these symptoms or feel like you may faint, there are some strategies you can use to help prevent it. Since fainting is caused by a disruption in blood flow to the brain, it’s recommended that you try to return blood flow to the brain. Some strategies to do so and prevent the onset of fainting include lying down with your legs raised over your head or sitting with your head between your knees. Other ways to prevent fainting are to make sure you’re drinking enough water and eating food at regular intervals to avoid feeling dehydrated or having low blood sugar. Another note about fainting is that episodes tend to last for less than a minute, but it’s recommended that you wait at least 30 minutes before standing up to avoid fainting again.

It's worth mentioning again that while fainting may be a familiar experience, getting evaluated by a health care provider is the best way to rule out more serious sources. If you aren’t sure what’s causing your fainting, episodes happen over a short period of time, or you frequently feel as if you might faint, you may want to consider seeking medical attention. Here’s hoping you have few, if any, fainting spells in the future. And please, dear reader, be careful out there!

Last updated Oct 16, 2023
Originally published Jan 17, 2014

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