What Causes an Itch?
An itch occurs when something irritates the skin. If the irritation is strong enough, it could be painful. If the irritation is slight, you’ll probably feel an itch. An itch may be caused by an irritation from chemicals that come into contact with the skin, such as clothing dyes.
An allergy to certain things can cause itching. Insect bites usually make you itch and scratch. An itch can also be caused by an infection, such as athlete’s foot. There are imaginary itches, too. Sometimes, just thinking about itching can make you want to scratch yourself.
Human skin most often gets itchy because of dryness associated with the environment or over-washing — water and soap can strip skin of its natural oils, thus sapping moisture. Face or body lotion should be able to keep these types of itches under control; also look for body washes and soaps labeled “moisturizing.”
If you still have itchy patches, you may be experiencing an allergic reaction to a chemical, plant, food, animal or drug. See an allergist if the itching is persistent.
From a survival perspective, there isn’t a good explanation for why we itch. One theory goes that animals itch in order to get parasites off their skin, and our desire to scratch an itch could be a carryover from that instinct.
Another possible explanation is that pain and itch engage many of the same areas of the brain. When you scratch an itch, you cause yourself enough pain to relive the itch, temporarily. Regardless, itches are best left unscratched.