An itch on the tip of your nose can feel different from one on your rear end—and possibly a bit more painful. Why is that? Shouldn’t your body treat an itch like an itch, no matter where it pops up?
According to a new study from North Carolina State University, your body treats itches on your face much differently than it treats them on the rest of your body.
The study found that your body sends itch signals from the face and the rest of the body along different routes to your brain, where they are processed. It’s as if your body has two different “itch phone lines” communicating with the brain—one from the face and another from the rest of the body.
Itches travel to your brain differently throughout the body
An itch on your arm starts with irritation of the skin—perhaps from dryness—then travels through the dorsal root ganglia, the spinal cord, and finally to the brain. An itch on your face goes from the spot of irritation to a different system called the trigeminal ganglia, and then to the brain.
Here’s the straight science:
“You can think of itch being transmitted from the skin to the brain as a series of switches that get flipped,” Santosh Mishra, associate professor of molecular biomedical sciences at NC State, said in a statement.
“On the body, itch signals go from neuronal projections in the skin through the dorsal root ganglia (DRG) – which are clusters of sensory cells located at the root of the spinal nerves – then to the spinal cord. But on the face and head, those signals travel to the trigeminal ganglia (TG) – which are clusters of sensory cells located in a small structure below the brain where it sits atop the skull,” Mishra added.
Your body sends mixed signals to your face
The researchers also discovered why an itch on your face may feel different from one on your torso. Studies showed that when histamine, an itch-inducing substance, was applied to the neck and cheek, the cheek itched less than the neck. Researchers initially assumed this was because there are fewer nerves in the cheek, but they were wrong: the cheek actually has far more. Instead, the face sends itch and pain signals simultaneously, and pain often overrides the sensation of itching. In the rest of the body, those signals are separated. That’s why an itch on your face feels different and may even be more painful than one on your arm.
Now that we know why an itch on your cheek feels different from one on your stomach, researchers can work on therapies that better address skin irritation on different parts of the body. One day, you may have a separate cream for a facial itch and another for one on your torso—not because of marketing, but because of real science.
“Understanding how itch perception in the face differs from itch perception in the body could give us better molecular targets for future therapies,” Mishra said.
