Why Do We Itch?

What exactly is an itch, and why do we have to scratch it? I mean this in the literal sense.

"The itch sensation is a perception," says Dr. Zhou-Feng Chen, a professor at the Washington University School of Medicine Pain Center. "It's something that comes from your brain. When a mosquito bites you, or poison ivy touches your skin, your skin releases chemical factors that cause inflammation. So there must be itch receptors in your skin that pass the information to the spinal cord, and the spinal cord passes this information on to the brain. Just like when you go to New York, you have to go through several cities before you reach New York, from the skin to the brain there are several relay stations that pass the signal one by one."

No more similes, Doc. He wants it literal.

"The brain probably has an itch center, which will decode the information —Okay, this is an itch — and the brain will instruct the body to respond, to scratch. All animals have evolved some kind of a mechanism to get rid of anything attached to their skin. That's why the itchy sensation is such an ancient sensation."

Dr. Scott Moses, a physician who specializes in the treatment of chronic itching, notes, "There are a lot of adverse effects of itching and scratching. The itch is completely harmless when you don't scratch, but when you scratch, it causes all these different secondary effects that can spiral into more scratching. If you have to respond, don't scratch — rub."

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Why do some people sweat so much?

You're trucking along on the treadmill and as you reach for a towel to wipe off the perspiration on your forehead, you can't help but notice the guy to the right who's sweating so much. It looks like he bathed in a pond. Why is it that some people sweat like crazy and some are barely glistening?

Sweating is the way of reducing our internal body temperature and maintaining a healthy temperature. We are born with between two and four million sweat glands. Women have more sweat glands than men, but men's glands are more active than women’s. How much we sweat depends on our gender, the number of sweat glands we have, how hot it is, how intensely we are exercising, or how anxious we feel.

The amount a person sweats also depends on how many sweat glands are activated and how much sweat is excreted from each gland. Unfortunately, some people suffer from excessive sweating, a common condition called hyperhidrosis. Their bodies' faucets turn on and their palms, feet, back, and face become covered in sweat, even if it's cold out or they're not moving. If this sounds familiar, consult your doctor to see what treatment options are available.

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