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.

General Mills Is Recalling More Than 600,000 Pounds of Gold Medal Flour Over E. Coli Risk

jirkaejc/iStock via Getty Images
jirkaejc/iStock via Getty Images

The FDA recently shared news of a 2019 product recall that could impact home bakers. As CNN reports, General Mills is voluntarily recalling 600,000 pounds of its Gold Medal Unbleached All-Purpose Flour due to a possible E. coli contamination.

The decision to pull the flour from shelves was made after a routine test of the 5-pound bags. According to a company statement, "the potential presence of E. coli O26" was found in the sample, and even though no illnesses have been connected to Gold Medal flour, General Mills is recalling it to be safe.

Escherichia coli O26 is a dangerous strain of the E. coli bacterium that's often spread through commercially processed foods. Symptoms include abdominal cramps and diarrhea. Most patients recover within a week, but in people with vulnerable immune systems like young children and seniors, the complications can be deadly.

To avoid the potentially contaminated batch, look for Gold Medal flour bags with a "better if used by" date of September 6, 2020 and the package UPC 016000 196100. All other products sold under the Gold Medal label are safe to consume.

Whether or not the flour in your pantry is affected, the recall is a good reminder that consuming raw flour can be just as harmful as eating raw eggs. So when you're baking cookies, resist having a taste until after they come out of the oven—or indulge in one of the many edible cookie dough products on the market instead.

[h/t CNN]

Doctors at a British Hospital Are Now Prescribing Houseplants for Depression

Halfpoint/iStock via Getty Images
Halfpoint/iStock via Getty Images

You don’t have to take a trip to the countryside to reap the mental health benefits of being around nature—a single plant might just do the trick (as long as you can keep it alive).

Fast Company reports that the Cornbrook Medical Practice in Manchester, England, is one of the first in the country to prescribe houseplants to help treat anxiety and depression. It’s part of a horticultural therapy program led by a local nonprofit called Sow the City, which leads initiatives to foster community gardens in Manchester.

It’s just as much about building a sense of community through gardening as it is about the therapeutic advantages of caring for your own house plants. “There’s evidence that people who are socially isolated have worse health outcomes,” Sow the City director Jon Ross told Fast Company. The organization has also assisted Cornbrook Medical Practice in establishing its own herb garden, which patients are welcome to help maintain. Ross and his team work closely with doctors at different offices to optimize each garden for its particular clientele—sometimes, that means building a small, flora-filled sanctuary that’s just for rest and relaxation.

Other times, it’s a fully-fledged vegetable garden. For a “Hospital Beds” program at another hospital, Sow the City installed raised vegetable beds where long-term mental illness patients can soak in some sunlight, socialize with each other, and take pride in seeing the fruits (and vegetables) of their labors flourish. There’s an added physical health benefit, too: The patients get to eat the produce. “We really don’t have good food in our public hospitals,” Ross said.

Sow the City also makes sure that no green thumbs are necessary to participate in any gardening party. Its members populate the gardens with already-healthy, easy-to-tend plants, and they’ll even train patients on how to care for them.

If you’re thinking a garden might improve your own quality of life—doctor’s orders or not—here are 10 easy-to-grow plants for first-time gardeners.

[h/t Fast Company]

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