Top five medical myths you probably believe are true -- but they're not

CRACK THOSE KNUCKLES

While cracking your knuckles is an unpleasant habit and may eventually injure your joints and weaken your fingers if you do it excessively, it will not cause arthritis. That's just a myth -- or something your mother told you to get you to stop doing it. There is a lot of homegrown medical advice most of us believe is true, but it's actually not. The top five medical myths you probably believe are true -- but they're not, according to the editors of Editors of Publications International:

1. Chocolate and friend foods cause acne.
When oil glands under the skin produce too much of a waxy oil called sebum, which the body uses to keep skin lubricated, pimples form. They're most likely caused by hormones, but stress and heredity also come into play.

2. Coffee will sober you up.
Once alcohol is in your system, no other liquid -- be it coffee, soda or water -- will sober you up. Only your liver can do that job.

3. Cold weather will give you a cold.
Viruses cause colds, not the weather. You catch a cold by inhaling airborne droplets after an infected person coughs or sneezes, shaking hands with someone who has a cold or touching a surface, such as a light switch, door handle or remote control, that harbors cold germs.

4. Too much sugar makes kids hyperactive.
Although you do want to restrict high-calorie sweets because they offer little nutrition, they won't make your child hyper. They will give a short-term energy boost, but that's not the same thing as hyperactivity.

5. Don't swallow gum because it takes seven years to digest.
Of the four ingredients in gum -- flavor, sweeteners, softeners and gum base -- the first three are digestible. But gum base is not, so it comes out the other end pretty much intact in about two to three days.