Subtitles section Play video Print subtitles - Triss, can you scratch my back? - Yeah, right there? - Yeah. - Down a little bit. - OK. - Yeah. Oh, yeah, that's it. Don't stop. Hey, guys, Tara here with an answer to one of life's greatest mysteries: Why is scratching an itch always make it worse? Every one of us has been bitten by a mosquito at some point. It actually happened to a friend of mine last week, and he ended up scratching it so hard he created an open wound, the size of a dime which is disgusting. But we've all been there, well, some of us. Most of us get a bug bite, we scratch it for a while and then in a few days it goes way, and we never think about it again. But believe it or not, there are millions of people out there who suffer from chronic itching. Conditions like eczema and even cancer or kidney failure can worsen it, and in many cases it can have a serious impact on someone's life. Well, it boils down to serotonin. Serotonin is a neurotransmitter that regulates tons of different functions in your body. Your mood, your memory, your sleep, your appetite, even blood clotting. It produces feelings about happiness and well-being but it also controls pain, and that's where the itching part comes in. Chu Fang Chen, as a researcher at Washington University, and he's been conducting studies over the years to see what produces the urge to itch. His most recent one involved mice who were genetically engineered to produce no serotonin. And he found that when those mice were injected with a chemical to induce itching, they had almost no urge to scratch. Meaning that the urge to scratch an itch begins as soon as serotonin leaves your brain and reaches the irritated spot, so whenever we scratch an itch we're actually doing so because the pain of scratching temporarily overrides the itchy feeling. The problem is that that pain causes your brain to release more serotonin, which intensifies the itch even more. So it's essentially a feedback loop where you're constantly scratching harder and harder to get rid of the itchy feeling, but all you're doing is really making it even more itchy. It make sense but it does bring up another interesting question: Why does serotonin cause an itchy sensation to begin with? Well, according to Chen, it has to do with GRPR neurons, which are a group of brain cells known to increase itchy sensations. A serotonin starts rushing to the part of your body that's irritated, its wires basically get crossed, and it activates those GRPR neurons which intensifies the itch even more. Chen believes that people who suffer from chronic itching could find relief once a therapy is developed to block the receptor that cause the serotonin to activate those neurons. Until then, the best solution seems to be lots of anti-itching cream and other mittens, the softer the better. My suggestion, not his. What do you guys think? Have you ever scratch the itch so hard that made you bleed? And how did that work out for you? Feel free to share your experiences with us in the comments down below. And as always, thank you guys for watching.