Most people get an itch at some point every day. In fact, itches are so common, you may not notice it until you start scratching. In some cases, the trigger for an itch is obvious: an old bug bite or an annoying shirt label. But what about itches that have no visible cause?

In a recent video, Get Science explained some of the science behind the classic itch. For example, according to Get Science, an itch is spurred when an irritant on the skin causes the skin neurons to send a signal to the brain to get rid of the skin invader. However, not all itches are caused by something on the skin. Some itches have an internal source. Known as invisible itches, these can be caused by allergies, cosmetic products, medications, or other chemicals from the environment, the University of Kentucky reported.

Read: Scratching Itchy Skin Causes Brain To Release Hormone Serotonin, Intensifies Itchy Sensation

In addition, a number of health conditions such as psoriasis, an autoimmune disease that causes individuals to develop thick red patches on their skin, and eczema, a condition that causes skin to become inflamed and irritated, can also cause chronic itchy skin.

What’s more, in serious cases, inexplicable itches can be due to a number of serious health conditions, such as liver disease, leukemia, and lymphoma, Healthline reported.

When we itch, our initial reaction is to scratch it with our fingernails. According to Get Science, this is because the pain of scratching helps to override the sensation of an itch.However, this can also create a vicious cycle, as eventually the pain of scratching is blocked out by serotonin in the brain. Without the pain as a distraction, we then feel the itch again. And so the cycle repeats.

According to Get Science, the best way to avoid this cycle from beginning is to avoid scratching in the first place, and instead, give an itch with no external source a little slap or rub.

To learn more about the science of itches, check out the video below!

See Also:

Scratching An Itch Activates Pleasure Centers In The Human Brain: Study

Poison Ivy Relief? Scientists Stop Itchy Rash By Blocking Skin Protein