Medical Myths and Wives' Tales

"Don't cross your eyes - they'll get stuck that way!" Remember hearing that as a child? You probably figured out on your own - when your eyes didn't stay crossed - that it wasn't true. Some old wives' tales, though, aren't as easy to debunk, since they are repeated so often and believed by so many. Ask yourself these true-false questions to see if you can separate medical fact from medical myth.

1. You can catch poison ivy from someone who has it.

   False. The only way to get the rash is from contact with the oil (urushiol) of the poison ivy plant. As long as urushiol has been washed off, you can't catch poison ivy from exposure to the rash.

2. Reading in dim light or sitting too close to the TV damages your eyes.

   False. You can't damage your eyes by using them, unless you stare into the sun.

3. Hair and fingernails continue to grow after death.

   False. The skin around hair and nails retracts after death, giving them the illusion of growth.

4. Shaving your hair causes it to grow back darker, coarser and faster.

   False. If this were true, all men who shave would have dark, coarse beards.

5. Swallowed gum is harmful to the digestive system.

   False. Swallowing gum really presents no danger. Contrary to what we've all heard, it doesn't remain in our stomachs for seven years. Gum passes swiftly through the digestive system, but because of the body's inability to break it down, exits the body looking pretty much the same as when it entered.

6. Knuckle-cracking causes arthritis.

   False. No evidence exists that this is true.

7. Drinking warm milk makes you sleepy.

   True. Milk contains tryptophan, a chemical that induces sleep.

8. You can get the flu from the flu shot.

   False. The vaccine is made up of inactive organisms that cannot cause the flu.

9. We use only 10 percent of our brains.

   False. Scans of the brain reveal 100 percent activity. In the course of a day, every part of the brain is used.

10. It's easier for a couple to conceive if the man wears boxer shorts instead of briefs.

    False. Underwear type doesn't affect fertility.

11. Eating turkey causes drowsiness.

    True. Turkey does contain tryptophan, which can make you sleepy especially when eaten on an empty stomach.

12. You should wait one hour after eating before swimming.

    False. As long as you aren't uncomfortably bloated, there's no need to wait.

13. Teething causes fever, runny nose and diarrhea.

    False. These symptoms may happen during teething, but aren't caused by it. (But, you still need to talk to your doctor about your baby's symptoms even if they are teething.)

14. Before modern pregnancy tests, if a rabbit injected with a woman's urine died, the woman was pregnant.

    False. The rabbit died whether or not there was a pregnancy. It was killed so its ovaries could be examined. Certain changes meant the woman was pregnant.

Related Articles Q&A: Eating Disorder Myths Abound What Fears and Myths Still Surround Epilepsy? Colon and Rectal Cancer Myths Abound

External Sources University of Arkansas for Medical Sciences University of Washington Nemours Foundation

This article was reviewed and updated June 2007.

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