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.

11 Facts About Anemia

David Gregory & Debbie Marshall, Wellcome Collection // CC BY 4.0
David Gregory & Debbie Marshall, Wellcome Collection // CC BY 4.0

Anemia is so pervasive that the word anemic has become synonymous with a lack of vitality, substance, or flavor. But anemia symptoms go beyond the common signs of pallor and fatigue. The disorder is characterized by a lack of red blood cells or hemoglobin in the body that arises from a variety of underlying conditions—some that are serious and others that are barely noticeable. Anemia causes can even include pregnancy, poor diet, and cancer in rare cases. Here are some more facts worth knowing about anemia symptoms and treatments.

1. The most common type is iron deficiency anemia.

The body needs iron to produce hemoglobin—the protein that allows red blood cells to transport oxygen throughout the body—and when it doesn’t get enough of it, iron deficiency anemia can develop. Vitamin deficiency anemia works in a similar way. The vitamins B12 and folate are also essential to producing healthy red blood cells, and deficiencies in either vitamin can contribute to anemia. Patients may be lacking iron, B12, or folate because they’re not getting enough of the vitamins or mineral from their diet, or because their body has trouble absorbing them, either due to gastrointestinal surgery, a genetic disorder, or some other issue. In contrast, sickle cell anemia is an inherited condition in which malformed hemoglobin can't carry enough oxygen, causing blood cells to take on a crescent shape and impede blood flow.

2. Even mild anemia symptoms should be taken seriously.

There are roughly 400 different anemia causes. Some are relatively benign, like not including enough leafy greens in your diet, while others are more serious, like blood cancers or aplastic anemia, a condition that develops when bone marrow stops producing red blood cells at a healthy rate. Mild anemia may be one of the first signs of a serious condition that impedes your blood cell production, so even if the symptoms of the anemia itself are manageable, it shouldn’t be brushed off as nothing.

3. Anemia is Greek for lack of blood.

Put simply, someone with anemia doesn’t have a healthy amount of red blood cells or hemoglobin in their bloodstream. The word is a Latinized version of the Greek word anaimia, which means lack of blood (an meaning "without" and haima meaning "blood").

4. The fatigue comes from a lack of oxygen.

Even with a healthy respiratory system, the tissues of people with anemia may not get enough oxygen—a phenomenon known as hypoxia. This can lead to symptoms like headaches, dizziness, shortness of breath, and fatigue. While these symptoms can be debilitating in patients with severe anemia, they may be mild or even nonexistent in people with less severe cases. The signs are also hard to measure and can overlap with those of several chronic conditions, which means mild anemia often goes undiagnosed.

5. Anemia compels some people to chew ice.

Constantly craving an ice cube to chew on may be a sign your blood is at anemic levels. Pica is the medical term for the compulsion to chew substances devoid of nutritional value, like ice, dirt, and paper, and it's one of the more distinctive symptoms of iron deficiency anemia. Doctors still aren't entirely sure why the craving afflicts so many anemic patients. One explanation is that ice calms inflammation in the mouth that sometimes comes with iron deficiencies, while additional research suggests that chewing on ice is one way for fatigued people to stay alert.

6. It’s diagnosed with a simple blood test.

Though the symptoms can be tricky to identify, testing for anemia is simple once a doctor suspects a patient has it. After taking a sample, doctors calculate the complete blood count, or CBC, which measures the percentage of red blood cells (a measurement called the hematocrit) and hemoglobin in a patient’s blood. By looking at red blood cell and hemoglobin percentages specifically, they can determine if the patient’s blood is healthy or anemic. The typical adult man has blood with 40 to 52 percent red blood cells (the rest is plasma), and for the typical adult woman, it’s 35 to 47 percent, according to the Mayo Clinic.

7. Anemia is more common in developing nations.

Approximately 25 percent of the world population—almost 2 billion people—is affected by anemia. In about half of these cases, iron deficiency is the root cause. Anemia is more common in developing parts of the world where malnutrition is also rampant, while in the U.S., just under 6 percent of the population is anemic. In the U.S., the prevalence of anemia varies by group: Women, elderly people, African Americans, and Latino Americans are all more likely to have it, with black women between ages 80 and 85 developing the condition at rates 6.4 times higher than the national average, according to a 2016 study. The majority of anemia cases around the world are moderate or mild, and at those levels the lack of healthy blood cells itself doesn’t pose significant health risks (though an underlying disease that's causing it might).

8. Anemia also has a surprising benefit.

Having a low amount of iron in your body has an unexpected effect: It makes it harder for infections to develop. Most bacteria depends on iron to gain strength and spread throughout a host, and in the bodies of people with iron deficiency anemia, bacteria has a greater chance of dying before it multiplies into a dangerous infection. Studies have shown that people with low iron counts have a smaller risk of contracting malaria, tuberculosis, and certain respiratory conditions. Iron deficiency anemia can also boost survival rates in patients with HIV and lower the risk of cancer (like bacteria, cancer cells need iron to grow). Denying pathogens iron is such an effective way of killing them that our bodies naturally slow iron production when they detect an infection.

9. Pregnant people are more likely to have anemia ...

People who are pregnant have a much higher risk of becoming anemic. According to the World Health Organization, anemia affects over 40 percent of pregnant women worldwide. The bodies of pregnant women naturally produce about 20 to 30 percent more blood to supply oxygen to the baby, but it isn’t always enough for the mother to maintain healthy red blood cell and hemoglobin levels. Anemia is especially common during the second and third trimesters when the baby needs the most blood. Pregnant patients with anemia are usually prescribed iron supplements to prevent birth defects and complications during delivery.

10. … and so are vegetarians.

Many people get their iron by eating meat like beef, chicken, pork, and shellfish. Without meat in their diet, people have a greater chance of developing iron deficiency anemia: A small Indian study published in the Journal of Nutrition & Food Science found that approximately 60 percent of vegetarian women were anemic. But it is possible to consume healthy amounts of iron while adhering to a meat-free diet. In addition to dietary supplements, legumes, dried fruits, and leafy greens are great sources of the mineral.

11. Anemia treatments range from vitamins to blood transfusions.

Treatments for anemia vary depending on the cause of the condition. For iron deficiency anemia, the most common variety, doctors usually prescribe iron supplements as well as a diet rich in the foods mentioned above. Daily folic acid tablets and B12 shots—starting once every other day and transitioning to once a month—may also be prescribed to patients deficient in either vitamin. In cases when red blood cell and hemoglobin counts dip into dangerous territory, more drastic treatments like blood transfusions and bone marrow transplants may be necessary.

Hawaii Has Been Named the Healthiest State in America

iStock.com/FatCamera
iStock.com/FatCamera

Hawaii may be thousands of miles removed from the continental U.S., but the state's residents don't seem worse off for it. As Thrillist reports, America's 50th state also happens to be the healthiest one in the nation.

This finding comes from the United Health Foundation, which releases the "America's Health Rankings Annual Report" each year. Factors that affect both physical and mental health, as well as social well-being, are taken into account.

"For nearly three decades, America's Health Rankings Annual Report has analyzed a comprehensive set of behaviors, public and health policies, community and environmental conditions, and clinical care data to provide a holistic view of the health of the people in the nation," the foundation writes on its website.

Hawaii has been named the healthiest state in the U.S. nine times since 1990, when the first report was released. So what exactly are our island-dwelling counterparts doing right? For one thing, the state has low obesity and smoking rates compared to the national average. Residents enjoy low levels of air pollution, very little mental distress among adults, and a high number of available primary care physicians.

Following Hawaii, the healthiest states in the nation are Massachusetts, Connecticut, Vermont, and Utah. The report also highlights the unhealthiest states—or, as the foundation delicately puts it, those that have "the greatest opportunity for improvement." Louisiana fared worst overall for health, largely because of its high rates of smoking, obesity, and children who live in poverty (28 percent). Mississippi comes in 49th place, followed by Alabama, Oklahoma, and Arkansas.

Maine saw the most improvement overall, having jumped seven places to number 16. It primarily improved in the areas of smoking and child poverty. Dropping four places, Oklahoma was the state that saw the biggest decline. Its obesity and physical inactivity rates both went up.

Check out the full report here [PDF] for more details on the state of the nation's health, or scroll down to see the state ranking.

1. Hawaii
2. Massachusetts
3. Connecticut
4. Vermont
5. Utah
6. New Hampshire
7. Minnesota
8. Colorado
9. Washington
10. New York
11. New Jersey
12. California
13. North Dakota
14. Rhode Island
15. Nebraska
16. Idaho
17. Maine
18. Iowa
19. Maryland
20. Virginia
21. Montana
22. Oregon
23. Wisconsin
24. Wyoming
25. South Dakota
26. Illinois
27. Kansas
28. Pennsylvania
29. Florida
30. Arizona
31. Delaware
32. Alaska
33. North Carolina
34. Michigan
35. New Mexico
36. Nevada
37. Texas
38. Missouri
39. Georgia
40. Ohio
41. Indiana
42. Tennessee
43. South Carolina
44. West Virginia
45. Kentucky
46. Arkansas
47. Oklahoma
48. Alabama
49. Mississippi
50. Louisiana

[h/t Thrillist]

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