Why Does Scratching Make Itching Worse?

iStock/champja
iStock/champja

It feels like a biological blooper: A persistent itch is made worse by scratching, the one thing that provides instantaneous relief. Evolutionary biologists have proposed that the relationship between scratching and itching developed when disease-carrying parasites and insects bit humans, causing itching skin; scratching brushed the bugs away. Anyone suffering from a mosquito bite can understand that connection.

There’s no simple answer for why skin that has just been scratched becomes even itchier, but researchers have identified some mechanisms behind the irritating phenomenon.

Why Scratching an Itch Doesn't Help

Our sensory neurons are constantly bombarded with stimuli, so some sensations take precedence over others. Sensory signals of one type can be overridden by signals of other types if the latter are strong enough. The overridden signals don’t even reach the brain—they’re stopped by specific neurons in the spinal cord. In this way, the pain caused by scratching is often sufficient to drown out the itch—but only temporarily.

Cells in the brain stem produce the neurotransmitter serotonin, which quells pain. But according to Zhou-Feng Chen, Ph.D., director of the Center for the Study of Itch at Washington University School of Medicine in St. Louis, Missouri, serotonin has an additional function. His group has found that as the serotonin spreads through the spinal cord, it can activate neurons that transmit itch signals to the brain, compelling us to scratch even more.

Each time we scratch, we put this cycle in motion. The increasing amount of serotonin may even make us scratch harder, until the urge to scratch becomes detached from any itch trigger on the skin. “It’s to try to suppress the itchy sensation, which occurs in your brain,” Chen tells Mental Floss. By this mechanism, itches can even become chronic.

Serotonin signaling isn’t the only way scratching worsens an itch; harm to the skin caused by scratching is another contributor. “When the skin barrier is irritated or further damaged, it releases certain pro-inflammatory factors that can directly aggravate itch by stimulating the sensory nerve fibers,” Brian Kim, M.D., co-director of the Center for the Study of Itch, tells Mental Floss. Those factors can also activate your immune system, and some types of immune cells around the affected area may produce chemicals that induce itch.

The very idea of scratching can also be a trigger. Chen’s research group reported last year that mice appear susceptible to scratching when they see other mice do the same. “Itching is actually contagious between people, between animals, and in your body itself,” Chen says. “When you scratch one place, you quickly want to scratch another area.” Scratching doesn’t just make itch more intense—it sometimes also causes the sensation to spread.

Relief for Itching

In mild cases, it may be possible to resist scratching through sheer force of will—but that’s not usually a long-term solution.

“I always feel bad because a lot of people say to patients, ‘Don’t scratch, don’t scratch,’ but that’s very challenging,” Kim tells Mental Floss. He says he tries to determine the cause of a person’s itchiness first. If it’s caused by an underlying medical problem, such as infestation with lice or liver disease, managing that issue may resolve the itch. Even if the underlying problem can’t be cured, there are medications that can calm itch in certain circumstances, such as antihistamines for allergy-induced itch and topical corticosteroids for itch caused by certain skin conditions, including eczema.

For now, drugs like these may be our best weapons against itching. “I think itch is often viewed as quirky, not serious, or embarrassing,” Kim says, which explains why there’s little research on itch despite its impact on our lives. Unfortunately, that coveted scratch in a bottle remains out of reach.

These ASMR-Ready Headphones Promise to Lull You to Sleep

AcousticSheep
AcousticSheep

What do hushed whispers, gently tapping fingernails, and Bob Ross’s voice have in common? They’re all examples of triggers that may cause what’s known as an autonomous sensory meridian response (ASMR), or, as Dictionary.com succinctly explains it, a “calming, pleasurable feeling often accompanied by a tingling sensation” that can be triggered by soothing stimuli. ASMR has recently been recognized as an effective relaxation technique for those looking to calm their nerves; now, ASMR enthusiasts and novices alike can experience it in the form of a sleep-ready headband.

Upon first glance, SleepPhones: ASMR Edition may look like just a fabric headband, but the device actually features flat speakers tucked into soft, stretchy, eco-friendly material. Unlike regular headphones, SleepPhones can be worn comfortably to bed, even if you sleep on your side, and they come preloaded with content designed to help you relax. They feature eight hours of built-in ASMR content by 16 different ASMR artists (or ASMRtists), including but not limited to tracks with rhythmic tapping and "peaceful Italian whisperings."

A close-up of the SleepPhones speaker technology
AcousticSheep

The speaker components of SleepPhones
AcousticSheep

Using SleepPhones is designed to be a stress-free experience. The speakers have the ability to play for 20 ad-free hours with a mere three-hour charging time in between. There are also zero cords involved, meaning you won’t get all tangled up as you lie down or if you have a tendency to toss and turn at night. The small button located in the back of the headband allows you to start, pause, or skip tracks and control the volume.

For people looking for ways to relax beyond yoga and meditation, ASMR may be the way to go. One study observed that subjects watching ASMR videos not only reported feeling that aforementioned pleasant tingling, but were also found to have reduced heart rates.

You can get a pair of your own SleepPhones on Kickstarter with a pledge of $75 or more. They come in three different sizes with seven colors from which to choose.

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FDA Is Warning Against Fecal Transplants After Person Dies From E. Coli Infection

iStock/artisteer
iStock/artisteer

Though it may sound gross, the benefits of a fecal transplant—taking the feces of one person and introducing it into the gastrointestinal tract of another—are promising for those suffering from a Clostridioides difficile infection. The tenacious infections are often the result of sustained antibiotic use, which can kill the patient's "good" gut bacteria and allow C. difficile to proliferate. As the theory goes, the “good” bacteria in feces transplanted from a healthy person may restore the infected person's microbiome and alleviate symptoms like life-threatening diarrhea.

The treatment, which is not FDA-approved, is risky. The FDA has announced that two people involved in a clinical trial recently received fecal transplants that contained drug-resistant bacteria, with one of them dying as a result.

According to The New York Times, the FDA did not offer details of either case, relating only that both patients were immunocompromised, which is one of the contraindications of receiving the transplant. The stool they received was believed to contain antibiotic-resistant E. coli bacteria.

As a result, the FDA is suspending a number of fecal transplant clinical trials until it can be determined how stool is being tested for contamination with potentially deadly bacteria and why the E. coli was not detected. The stool that infected both patients came from the same donor.

Fecal transplants are considered an experimental treatment for C. difficile infection when first-line treatment like antibiotics are ineffective. The fecal transplant is usually introduced to the digestive tract via pills or an infusion.

[h/t The New York Times]

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