Why The Heck Do We Itch? Science Has An Idea


No matter what challenges life brings you on the daily, nothing derails absolutely everything quite like an itch.

Sure it’s obnoxious, but why do we do it at all? Is there a biological benefit, or is it just one of those quirky evolutionary things science can’t explain?

Well, scientists aren’t entirely sure. What they do know has come primarily from studying mice. A subset of the nerves in mice that conduct pain signals to the brain create the itching sensation.

The working theory is that itching evolved to alert humans that something was on their skin that shouldn’t be, such as insects, poisonous plants, or dirt. The natural response to itching, scratching, often removes the irritant. Scratching also acts as a counter-sensation to the itch. Because you scratch, you don’t notice the itch as much, and you feel relief.

Dry Skin Is The Most Common Cause Of Itching


The most common cause of itchy skin (or pruritus) is dry skin. On the scalp, this same condition is called dandruff. You can treat it by applying moisturizer to your skin or medicated shampoo to your scalp. The Mayo Clinic relates that a similar and harmless condition, called cradle cap, can appear in infants, most likely caused by too much oil on the scalp, though doctors don’t all agree on what causes it.

Insect Bites Itch Because of Histamine


Insect bites can be among the most annoying of itches. When a mosquito bites you, it injects an anticoagulant into your skin, which reduces your blood’s ability to clot. Your body reacts by producing histamine, which causes your capillaries to swell, making the hungry mosquito very happy and you somewhat miserable as you get an itchy bump on your arm.

Ichthyosis Is A Rare Cause Of Itching

The British Journal of Dermatology, Wikimedia Commons

Certain diseases can also cause itching. We are all familiar with how chickenpox rashes itch, but a rare genetic skin disorder called ichthyosis can cause a person to itch throughout their entire life, and the typical medicines do not help.

Don’t worry — your itching isn’t likely symptom of that.

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