- Itchy skin (pruritus): Causes, treatment, and home remedies
- Dry skin
- Bug bites
- Other causes
- Itchy Skin & Itching: 22 Possible Causes You Feel Itchy All Over
- Itching: More Than Skin-Deep
- Pain and itch connected down deep
- Itch and pain aspects of touch
- Focus on wasabi
- When to start worrying about a chronic itch
- Definition of itch
Itchy skin (pruritus): Causes, treatment, and home remedies
Skin serves a vital purpose as the barrier that protects the inside of the body. It is filled with special cells of the immune system that can protect the body and skin from viruses, bacteria, and other hidden threats.
Once the skin cells detect any type of suspicious substance, they trigger a reaction that causes the area to become inflamed. Medical professionals refer to this inflammation as a rash or dermatitis. This can lead to itching.
Immune cells can react to something that touches the skin, a whole-body infection, or an illness. Some rashes are red, painful, and irritated, while others can lead to blisters or patches of raw skin.
Itching is a symptom common to many skin complaints. Skin can itch all over the body or only in specific areas.
Here are some specific causes of pruritus:
Dry skin is one of the most common causes of itchy skin. If a person does not see any bright red bumps or notice a sudden change to their skin, dry skin is a ly cause.
Environmental factors that can lead to dry skin include excessively hot or cold weather with low humidity. Washing too much can also cause dry skin. It can affect any age group, but as people age, their skin becomes thinner and drier.
A good moisturizer can usually help repair dry skin. Extremely dry skin can be a warning sign of dermatitis, so it may be necessary to see a dermatologist to help get relief and keep the condition from becoming worse.
Common signs and symptoms of dry skin include:
- rough, scaly, or flaking skin
- excessive itching
- gray or ashy-looking skin in people with darker skin
- cracks in the skin that are prone to bleeding
- chapped or cracked skin or lips
It is important to seek help to treat dry skin because cracks in the skin can allow germs to enter. Once inside the skin, these germs can cause an infection. Red, sore spots on the skin are often an early sign of a potential infection.
A skin specialist may prescribe a special moisturizer to apply throughout the day or a topical medicine to apply directly to the skin.
Eczema, or atopic dermatitis, is the most common cause of skin rash in children.
The American College of Allergy, Asthma & Immunology (ACAAI) report that eczema affects 1 in 5 infants but only 1 in 50 adults.
The cause is linked to the leakiness of the skin barrier. This causes the area to dry out, putting it at risk of irritation and inflammation. It is vital to keep the skin moisturized.
Eczema often improves over time. People with eczema must be careful, however, as they are more vulnerable to skin infections.
Irritation and allergic reactions can also cause itchy skin. Allergic contact dermatitis occurs when the skin comes into direct contact with an allergen.
The result of the skin allergy is a red, itchy rash that can include small blisters or bumps. The rash arises whenever the skin comes into contact with the allergen, a substance that the immune system attacks. Often, there is a time delay between exposure to the allergen and when the rash occurs.
Touching clothing, pets, chemicals, soaps, and substances such as poison ivy or cosmetics can trigger allergic reactions.. Food allergies can also cause the skin to itch.
Nickel allergies are quite common. When a person come into contact with jewelry that contains even a small amount of nickel, they can develop red, bumpy, itchy, and swollen skin at the point of contact.
For a person with an allergic reaction to a particular substance, one of the easiest things to do is to avoid that product or substance. Over-the-counter creams or medicated creams can help clear up a rash.
Hives are a type of skin inflammation caused by the release of a chemical in the body called histamine. This release causes small blood vessels to leak, which causes the skin to swell.
There are two kinds of hives:
- Acute hives. These most commonly occur after coming into contact with an allergic trigger, such as a particular food or medication. Non-allergic causes, such as excessively hot or cold weather, sun exposure, or exercise, can also serve as a trigger.
- Chronic hives. Specific triggers do not cause these, which can make allergy tests unhelpful. They can last for months or even years. Hives can cause uncomfortable itching and be painful, but they are not contagious.
The ACAAI say that hives affect about 20 percent of people at some point in their life.
Bug bites often cause a person’s skin to flare up, resulting in itchiness. Mosquito and spider bites will often produce a small bite mark that is surrounded by red patchiness on the skin. These bites should fade away within 7–14 days.
Bites from bed bugs and mites may produce a bigger rash and can cause itchiness all over the body. If a person suspects a bed bug infestation, they need to remove all furniture and clean the room thoroughly with repellent. All affected items should be washed at 60 ºC.
Professional help may be required if a person is unable to eliminate the infestation themselves.
People may experience an itching feeling that has no physical cause. Some mental health conditions can make a person feel as if their skin is crawling, which creates an urge to scratch. Excessive scratching can lead to skin damage.
Compulsive scratching may be the result of the following conditions:
- obsessive-compulsive disorder
Itching can also be related to parasites such as threadworms, insects such as bedbugs, mosquitoes, or lice. Fungal infections, such as athlete’s foot, can also cause itching between and around the toes.
Itchy skin could also be due to more serious medical conditions. Nerve disorders caused by diabetes, pinched nerves, and shingles can cause severe itching.
Doctors might also refer to uremic pruritus as renal itch or chronic kidney disease-associated pruritus. Uremia is a broad syndrome that occurs when the kidneys are severely damaged and cannot filter toxins from the body.
With uremia, itching tends to be worse at night. It most commonly affects the back, arms, and abdomen.
The following home remedies may help reduce itching:
- using a high-quality moisturizing cream on the skin and applying it at least once or twice each day
- applying an anti-itch cream, such as nonprescription hydrocortisone cream, to the area to help relieve the itching. Hydrocortisone cream is available for purchase online.
- applying a cool, wet compress to the affected area
- taking a lukewarm bath
- choosing mild soaps without dyes or perfumes and using mild or unscented laundry detergent when washing. Various products for sensitive skin are available for purchase online, including laundry detergent and soaps.
- avoiding substances that irritate the skin or cause an allergic reaction such as nickel, jewelry, and wool
Perhaps the most important self-care measure is to avoid scratching. Scratching can ultimately lead to further inflammation and damage to the skin and can worsen the itching.
If over-the-counter creams do not work, if a rash spreads, or if someone experiences additional symptoms beyond itching, they should see a physician or skin specialist to identify the cause and treat the particular problem.
The treatment plan will depend on the cause of itching. For people who are suffering from dry skin, a good moisturizer may be all that is needed.
Eczema, dermatitis, or hives: These and other skin conditions may be recommended corticosteroid creams by a skin specialist. These can be applied directly to the skin to help with itching. Topical calcineurin inhibitors and oral antihistamines can also help to relieve the itch.
Allergies: Oral antihistamines are common anti-allergy medications. They can be prescribed or purchased online. Examples include Zyrtec, Claritin, and Benadryl.
Fungal infections: Ringworm, athlete’s foot, and other fungal infections can be treated with antifungal treatment. Topical treatments include creams and shampoos. For severe infections, the doctor may prescribe an oral medication. Terbinafine, or Lamisil, is commonly used.
Insect bites and stings: Topical antihistamines can relieve itching. To prevent bites, use an insect repellant, keep fly screens in good repair, and keep the body covered with clothing.
People who have psoriasis or kidney failure may be recommended alternative treatments if there are reasons to avoid medication therapy. Light therapy or phototherapy is one such treatment method. The treatment involves exposing the skin to certain wavelengths of ultraviolet light to help get the itching under control.
Read the article in Spanish.
Itchy Skin & Itching: 22 Possible Causes You Feel Itchy All Over
You might have an itch that must be scratched. Or a tickle on your back that you can’t reach. It’s often hard to pin down just what’s causing it. It may be as simple as the clothes you wear. But it can also be a symptom of something more serious, a rash or an illness.
Start with the simplest solutions. Try a different fabric, take care of your skin, and avoid anything that seems to trigger the itch. If that doesn’t help, ask your doctor, who will check on the cause and the treatment you need.
Is Your Skin Dry?
If your skin is dry, it will let you know with an itch. It can be especially bad in the winter and in places where the air is dry. As you get older, it becomes even more common.
To ease the itch of dry skin:
- Use moisturizer after you bathe while your skin is still damp and again after you change clothes.
- Drink lots of fluids to stay hydrated.
- Use a humidifier.
- Make your shower quick, and don’t use very hot water.
- Use mild, hydrating soaps.
Learn more about how to prevent itching caused by dry skin.
Is There a Rash?
If you start scratching and find a rash, it’s ly the problem is in your skin. It can happen because of:
Fungal and bacterial infections impetigo and folliculitis. See a photo of what impetigo looks .
Bugs: When you get bitten by a mosquito or spider, you know it. Bites from bedbugs and mites can be harder to diagnose because they look rashes. Lice can cause a crawling sensation in your scalp or pubic hair, along with an intense itch. See a photo of what bedbug bites look .
Eczema or atopic dermatitis: It shows up on your skin as dry, scaly patches or a bumpy rash. It isn’t clear what causes it, but it’s extremely itchy. Kids are more ly to get it if their family has a history of asthma and allergies. Certain food allergies can make it worse. So does scratching. See a photo of what eczema looks .
Contact dermatitis: This itchy rash is caused by a reaction to something touching your skin. You may have to do some detective work to figure out where it’s coming from.
It could be the metals in your jewelry or the chemicals in cosmetics, toiletries, and cleaning products. Poison ivy is also a form of contact dermatitis.
Stop using or wearing whatever you think might be the cause and see if the itching gets better. See a photo of what a poisonous plant rash looks .
Is It Beneath the Surface?
Your skin may let you know when something is not quite right inside your body. This itch can be a symptom of deeper problems.
Hives: You get them from allergies. They look raised welts that show up alone or in clusters, and they are usually itchy. Stress, heat, exercise, or exposure to the sun can also bring them out. See a photo of what hives look .
Psoriasis: It makes your body overproduce skin cells, which pile up in itchy, inflamed patches on the skin’s surface. This is a result of an overactive immune system. See a photo of what psoriasis looks .
Pregnancy: More than 1 in 10 pregnant women say itching is a problem. The reasons range from harmless rashes to more serious conditions. Learn more about skin conditions in pregnancy.
Medications: Some may make your skin itch, even with no signs of a rash or irritation. Check with your doctor if the itch becomes too uncomfortable. These drugs are known to make you start scratching.
Is It Related to Your Nerves?
Your nervous system can get confused when it’s sick and accidentally tell the nerves on the skin to start itching when there’s nothing there to cause it. There is no rash. But your skin may appear irritated if you’ve been scratching a lot. You can get it from:
- Multiple sclerosis
- Brain tumor
- Nerve damage
Is It Psychological?
If your doctor can’t find a physical cause, it may be in your mind. Some mental conditions give people the urge to scratch or pick at themselves. They may feel their skin is crawling with something. There is no rash, but there may be skin damage from scratching. Compulsive scratching can be a sign of:
- Obsessive-compulsive disorder
Learn more about skin picking disorder.
Unly, but Possible
Itchiness usually has a simple, common cause. But in some cases, if it doesn’t go away, could be a sign of a serious illness, such as:
You might also start itching after the treatments for some of these illnesses. Kidney dialysis, chemotherapy, and radiation therapy have it as a side effect. Learn more about chemotherapy side effects.
American Academy of Allergy Asthma & Immunology: “Skin Allergy.”
American Academy of Dermatology.
Jain, S. Current Psychiatry, October 2013.
Moses, S. American Family Physician, September 2003.
National Cancer Institute: “Pruritus.”
National Psoriasis Foundation: “About Psoriasis.”
Oaklander, A. Acta Dermato-Venereologica, March 2012.
The Cleveland Clinic Foundation: “Pruritus.”
Yonova, D. Hippokratia, April-June 2007.
Yosipovitch, G. Dermatologic Therapy, March 2008.
© 2019 WebMD, LLC. All rights reserved. Scratching
Itching: More Than Skin-Deep
Continue reading the main story
The experiment was not for the squirmish. Volunteers were made to itch crazy on one arm, but not allowed to scratch. Then they were whisked into an M.R.I. scanner to see what parts of their brains lit up when they itched, when researchers scratched them and when they were finally allowed to scratch themselves.
The scientific question was this: Why does it feel so good to scratch an itch?
“It’s quite intriguing to see how many brain centers are activated,” said Dr. Gil Yosipovitch, chairman of dermatology at the Temple University School of Medicine and director of the Temple Center for Itch (he conducted the experiment while working at Wake Forest School of Medicine). “There is no one itch center. Everyone wants that target, but it doesn’t work in real life that.”
Instead, itching and scratching engage brain areas involved not only in sensation, but also in mental processes that help explain why we love to scratch: motivation and reward, pleasure, craving and even addiction. What an itch turns on, a scratch turns off — and scratching oneself does it better than being scratched by someone else. The study results were published in December in the journal PLOS One.
VideoA mouse scratching an itch.
Itching was long overshadowed by pain in both research and treatment, and was even considered just a mild form of pain. But millions of people suffer from itching, and times have changed.
Research has found nerves, molecules and cellular receptors that are specific for itching and set it apart from pain, and the medical profession has begun to take it seriously as a debilitating problem that deserves to be studied and treated.
Within the last decade, there has been a flurry of research into what causes itching and how to stop it. Along with brain imaging, studies have begun to look at gene activity and to map the signals that flow between cells in the skin, the immune system, the spinal cord and the brain.
The concern is not so much the fleeting nastiness of mosquito bites and poison ivy, but the unending misery caused by chronic itching — the kind that won’t go away, that torments people night and day and very often resists remedies antihistamines and cortisone cream.
For the first time in the United States, itching research and treatment centers have opened: Temple’s in September, in Philadelphia, and Washington University’s Center for the Study of Itch, in 2011, in St. Louis.
“Itch is now where pain was probably 20 years ago,” said Dr. Lynn Cornelius, chief of the dermatology division at Washington University School of Medicine. “It used to be lumped together with pain.”
But now, she said, there is more interest in itching and in sorting out its different types, and more research money being spent on it.
VideoA cheetah scratching an itch.
“The science has to lead to treatment, I believe,” Dr. Cornelius said. “If that happens, it will translate to better and better, more targeted therapies, so clinicians won’t just look upon someone itching as someone who needs antihistamines.”
Scratching, and therefore itching, appear widespread in the animal kingdom — though no one knows for sure why animals claw, bite or peck themselves, or scrape against trees or fences.
Even fruit flies engage in “robust grooming behaviors” that look a lot scratching when they are infected with mites, said Diana Bautista, an assistant professor of cell and developmental biology at the University of California, Berkeley. Her research includes studying various strains of itchy mice that are models for human ailments.
VideoA seal scratching an itch.
“I have a collection of movies showing different animals scratching,” Dr. Bautista said. “I’m hoping they will help me determine if there is a difference between itch-evoked scratching versus wiping and other behaviors in diverse species.”
One of her favorite videos shows a seal lying on the beach, briskly rubbing its head with a flipper.
In people, there are different types of itching. The most familiar type, from a mosquito bite or hives, occurs when cells in the skin release histamine, which causes nerves in the skin to fire off signals to the spinal cord and brain. Antihistamine pills or creams usually bring relief.
VideoA gorilla scratching an itch.
But antihistamines are often no help to people with chronic itching, which can be caused by skin diseases eczema or psoriasis, kidney or liver failure, dry skin, an overactive thyroid gland, certain cancers, and pinched or damaged nerves. And the itching from psoriasis almost certainly has a different mechanism from that caused by a pinched nerve.
“It’s a very hot area,” Dr. Cornelius said. “It’s a huge clinical problem and a huge unmet market.”
Recent research has shown that substances other than histamine, released from inflammatory cells, are involved in chronic itching, along with three different types of nerve cells, Dr. Bautista said. Drug companies are trying to find ways to block those substances.
“Before, the focus was on next-generation antihistamines,” Dr. Bautista said. “Now, it’s on new molecular and cellular targets to develop new therapies. The pharmaceutical industry is recognizing that they have to go beyond antihistamines.”
VideoThe African buffalo scratching an itch.
But pain pathways have to be dissected in minute detail if new targets are to be found.
Many researchers say that one of the most important advances in the field was reported in the journal Nature in 2007 by a Washington University team led by Zhou-Feng Chen, who is now director of the itch center.
Working with mice, his team was studying receptors, molecules on cells that respond to certain chemical signals to change the cells’ behavior.
The group was the first to find a receptor in the spinal cord that was specific for itching, called gastrin-releasing peptide receptor, or GRPR. The discovery helped to prove that signals for itching and pain travel on different pathways.
In an interview, Dr. Chen said that mice without the receptor — or with the receptor blocked by a drug — did not itch. Nor was the group without a receptor harmed by the lack of it.
VideoAn orangutan scratching an itch.
“If you block function of this receptor alone, you pretty much stop chronic itching,” he said.
The receptor is present in humans, too, and Dr. Chen said it might be possible to develop a drug that would block it.
For many patients, new treatments cannot come soon enough.
Chronic itching becomes more common with age. One reason is that older people often develop dry skin, but Dr. Yosipovitch said the itching also might occur because certain nerves in the skin deteriorate — nerves that transmit pain and inhibit itching. “Then itch kind of pops out,” he said.
Aging monkeys have provided some clues. When Dr. Yosipovitch was still at Wake Forest, he and his colleagues noticed older female macaques scratching their backs and lower limbs, the same spots where older people tend to itch.
VideoWildebeest scratch their itches.
They sent samples from the monkeys to Dr. Chen, who found extra activity in the skin and spinal cord from the gene that produces GRPR, the itch receptor. Why the gene becomes more active with aging is not known, but this finding in a primate supports the idea that the receptor is a good target for new drugs in people, Dr. Chen said.
Many older people have trouble with itching in hard-to-reach spots on the back, between or just below the shoulder blades.
“It drives them crazy,” said Dr. Cornelius, at Washington University. They rub against door jambs, stockpile back scratchers, and enlist others to scratch them.
ImageJoshua Riegel, 18, has a rare disease that was misdiagnosed as a mental issue and for which he was given antidepressants.Credit…Jeremy M. Lange for The New York Times
The condition has a name, notalgia paresthetica, and is often associated with spine and disk problems that pinch or damage nerves. The skin in the itchy spots may darken.
“Some neurologists, I would say the majority, do not know about this,” Dr. Yosipovitch said.
He and other doctors have prescribed various remedies — numbing patches, sometimes along with the hot-pepper ingredient capsaicin; Botox injections; pills gabapentin that affect nerve transmission; and physical therapy to change posture. Often, it is possible to find something that helps.
Dr. Yosipovitch said many patients found their way to him only after seeing multiple doctors who could not help and who sometimes misdiagnosed their problems as mental rather than physical.
“They’re not crazy,” he said.
One of the patients was a boy who had scratched his arms and legs raw. Unable to find a cause or a treatment that worked, doctors had referred him and his family to a psychiatrist.
In an interview, the patient, Joshua Riegel, now 18, said, “They said I was doing it to manipulate my parents.” Thus began what he calls “that weird part of my life where they thought I was mentally ill.”
He was 12 or 13 when the psychiatrist prescribed antidepressants, which he dutifully took for two or three years. But they brought on terrible side effects: At one point he was hospitalized with suicidal thoughts.
As a last resort, his parents took him from their home in Hillsville, Va., to see Dr. Yosipovitch, who was then at Wake Forest.
“He had a hunch on what it was,” Mr. Riegel said.
Tests found a rare form of a genetic disease, epidermolysis bullosa, that was causing a particularly destructive set of symptoms: intense itching and skin so fragile that scratching ripped it to shreds.
“Dr. Yosipovitch was quite angry I was being told I was mentally ill when I wasn’t,” Mr. Riegel recalled.
Getting off the antidepressants lifted his spirits and let him be normal again. Since then, other drugs have been prescribed for the itching, with mixed results. It never really goes away, but Mr. Riegel uses video games or his cellphone to take his mind off it and keep from scratching.
For people with other types of chronic itching, Dr. Yosipovitch said: “This is just the beginning of a big era. In the next five years I predict there will be drugs targeted specifically for itch. We’re in the middle of the tip of an iceberg.”
“,”author”:”Denise Grady”,”date_published”:”2014-02-17T20:46:25.000Z”,”lead_image_url”:”https://static01.nyt.com/images/2014/02/18/science/18ITCH_SPAN/18ITCH-articleLarge.jpg”,”dek”:null,”next_page_url”:null,”url”:”https://www.nytimes.com/2014/02/18/health/itching-more-than-skin-deep.html”,”domain”:”www.nytimes.com”,”excerpt”:”Long overshadowed by pain in terms of research and treatment, chronic itching is getting a serious look beyond just throwing antihistamines at it.”,”word_count”:1657,”direction”:”ltr”,”total_pages”:1,”rendered_pages”:1}
Pain and itch connected down deep
A new study of itch adds to growing evidence that the chemical signals that make us want to scratch are the same signals that make us wince in pain.
The interactions between itch and pain are only partly understood, said itch and pain researcher Diana Bautista, an assistant professor of molecular and cell biology at the University of California, Berkeley. The skin contains some nerve cells that respond only to itch and others that respond only to pain. Others, however, respond to both, and some substances cause both itching and pain.
If itch and pain are closely linked, however, the implications are huge, Bautista said. If pain and itch use the same molecules to communicate with the brain, drugs now being developed to alleviate pain may also help quiet intractable itch.
“Some types of itch respond to antihistamines, but most itch, especially itch associated with chronic diseases kidney and liver failure, diabetes and cancer, does not,” she said.
“Even allergic itch only partly responds to antihistamines.
We’ve shown that one of the drugs now being looked at by pharmaceutical companies as a pain reliever also blocks some types of histamine-independent itch.”
Bautista’s new research, published in this week’s print edition of the journal Nature Neuroscience, shows that two specific irritants induce itching by way of the wasabi receptor, a pain receptor familiar to sushi lovers.
Other recent studies have shown that some itch inducers – called pruritogens – lead to activation of the capsaicin receptor, a pain receptor named for the incendiary chemical in chili peppers.
“It’s starting to look many pain receptors are linked to the itch system,” she said. “Both itch and pain use some of the same molecules to send signals to the brain.”
Bautista has genetically altered mice so that they don’t produce the wasabi receptor, and hopes that the mouse strain will help lead to a better understanding of forms of itch that do not respond to antihistamines.
Itch and pain aspects of touch
Pain and itch are extremes of our sense of touch, which itself is not well understood, Bautista said. While research has shown in detail how touch receptors on the skin map to the brain, “it’s really an open question which molecules are involved in detecting tactile stimuli, vibrations or light touch, and how these molecules are modulated.”
In her lab, she applies a huge variety of chemical and physical stimuli to the skin in order to study and isolate the specific receptors that respond to such stimuli. She also grows skin cells and sensory neurons in dishes to probe them more thoroughly.
“One of the cool things about touch cells is you can put them in a dish, and you can poke them, and they’ll respond to touch with an electrical signal,” Bautista told the Daily Californian news outlet last year.
Five years ago, Bautista showed that allyl isothiocyanate, the sinus-clearing ingredient in wasabi, hot mustard and garlic, causes pain solely by activating a receptor called TRPA1 on sensory nerves.
The receptor is one of a group of transient receptor potential (TRP) ion channels in sensory nerves under the skin, including the mouth and mucus membranes, which detect temperature, mechanical abrasion and irritating chemicals.
The capsaicin and heat receptor, dubbed TRPV1 is another such ion channel, as is TRPM8, a cold-activated channel targeted by menthol and other cooling agents. When these receptors are activated, they open up and depolarize the nerve cell, which transmits an attention-grabbing pain signal through the spinal cord to the brain.
The pain work led to an interest in itch, and Bautista has accumulated a variety of agents that stimulate the itch reflex, including the plant called cowhage (Mucuna pruriens) and the drug chloroquine, an antimalarial that often causes a hellish, all-over itch. In some African countries, up to 70 percent of the population develops itch from chloroquine, which causes many people to stop taking it.
Only between 5 and 20 percent of the skin’s sensory nerves are sensitive to itch, and one group of them has histamine receptors that can be blocked by antihistamines to stop the itch.
Both chloroquine and cowhage, however, cause a histamine-independent itch, as do opium compounds; inflammation, from asthma and allergies to skin rash; and eczema.
These are currently untreatable and the focus of Bautista’s research.
A common feature of itch receptors is that they are members of a family of G protein-coupled receptors widely used by the body to transmit signals from outside the cell into the cell interior. Bautista’s colleague Xinzhong Dong in the Solomon H.
Snyder Department of Neuroscience at Johns Hopkins University School of Medicine in Baltimore recently identified two new itch receptors, both of them Mas-related G protein-coupled receptors.
One, MrgprA3, is stimulated by chloroquine, while the second, MrgprC11, is stimulated by BAM8-22, a peptide released by immune cells, including mast cells, during inflammation.
If sensory nerves contain pain receptors TRPA1 and TRPV1, and itch receptors MrgprA3 and MrgprC11, how does the cell distinguish between itch and pain? Bautista asked.
Focus on wasabi
Bautista tested both chloroquine and the mast cell chemical BAM8-22 on cultured mouse cells and found that both activate the wasabi receptor, TRPA1, causing a depolarization of nerve cells. In addition, knock-out mice that lack the receptor do not respond to either chemical, while a chemical that blocks the receptor also stops the itch.
Her interpretation of the results is that in sensory nerves with both the chloroquine itch receptor and the wasabi pain receptor, when chloroquine binds to its receptor, it subsequently opens the wasabi receptor, which depolarizes the nerve cell and sends an itch signal to the brain. Similarly, in the cells that have both a BAM8-22 itch receptor and a wasabi receptor, BAM8-22 triggers opening of the wasabi receptor. Both itch inducers trigger the pain receptors through G protein couplings inside the cell.
“These experiments provide a wonderful demonstration that chloroquine and BAM8-22 cause itch only through the wasabi receptor,” she said. “If both pathways converge on the same ion channel, perhaps other molecules that cause itch also use this channel.”
Bautista’s coauthors, in addition to Dong, are UC Berkeley graduate students Sarah R. Wilson and Kristin A. Gerhold and research associate Amber Bifolck-Fisher, and Johns Hopkins graduate students Qin Liu and Kush N. Patel.
The work is funded by the National Institutes of Health, including an NIH Innovator Award, the Pew Scholars Program, the Rita Allen Foundation, the McKnight Scholars Fund and the National Science Foundation.
When to start worrying about a chronic itch
I have an occasional “phantom” itch in the middle of my back in a place I can’t reach. I use a long-handled comb to give it a good scratch. There’s no obvious cause — no rash, no irritation or redness, no diagnosed skin disorder. It’s annoying, but it doesn’t disrupt my life.
Unfortunately, that’s not the case for everyone who itches.
About 15 percent of the population suffers from chronic itch, according to Brian Kim, co-director of the Center for the Study of Itch at the Washington University School of Medicine. “It’s a very big problem,” Kim says.
“Studies have shown that its impact on quality of life is equivalent to chronic pain. Many of my patients who have had both prefer pain over itch. Itch tends to be more maddening.”
Rockville, Md., dermatologist Thomas M. Keahey says itching is the chief complaint of about 20 percent of his new patients. Also, his older patients frequently raise the issue during their annual skin cancer screenings. Most of the time their problems are minor, but “sometimes, it’s a serious request for help,” he says.
There are hundreds of reasons people itch. These range from dry skin and such skin disorders as psoriasis, to “contact” dermatitis from rough clothing, pet dander, soaps, laundry detergents and perfume — collectively known as eczema — as well as more painfully familiar conditions such as bug bites or poison ivy.
Some people will break into hives after exposure to some external stimulus, such as cold air or the sun. “Can you fathom breaking out with itchy hives by walking outdoors into the cold or sunlight, or following a ‘healthy’ workout?” Keahey says.
There also are unexpected causes, some of them serious. These include diabetes, kidney disease and some cancers.
“One thing that may surprise people is that having a bad neck or back can cause itching due to damage to the nerves that come from your spinal cord,” Kim says. “Another thing people may not know is that in rare cases, cancer — particularly lymphomas and leukemias — can present with itch.”
All-over itching caused by blockage of the bile ducts can be a sign of pancreatic cancer, for example.
In cutaneous T-cell lymphoma, a type of non-Hodgkin lymphoma, the cancer begins in the white blood cells and attacks the skin, causing a chronic, itchy rash “often confused with benign forms of eczema,” Keahey says.
Also, about a third of patients suffering from end-stage kidney disease experience itching “due to a buildup of toxins, not well defined,” Keahey says.
Researchers are studying the itch-scratch cycle, trying to unravel the mysteries of what makes people itch, then scratch — and keep scratching. Scratching causes damage to the skin, which causes inflammation, Kim says. “This increased inflammation, with many rashes, causes more itch in a feed-forward manner,” he says. “Thus it’s a vicious ‘itch-scratch’ cycle.”
Kim and others believe the body’s immune system is a player. “We may think our immune responses end in our immune system,” Kim says. “But the itch-scratch cycle engages the immune system with the whole body, interacting with behavior and the environment as well.”
Recent research in mice suggests there is a link between itching and food allergies, which also are an immune response.
In the animals, scratching the skin prompted an increase in the number of activated mast cells — immune cells involved in allergic reactions — in the small intestine, indicating a possible relationship between food allergies and atopic dermatitis, a type of eczema, according to a study by scientists at Boston Children’s Hospital.
The brain also may be involved. In another mouse study, researchers at the Chinese Academy of Sciences showed that tinkering with a small subset of neurons in a brain region that processes sensory information, including pain, could prompt or halt scratching in mice, suggesting that these neurons are connected to the itch-scratch cycle.
Experts believe the cycle evolved over time among animals as a protective behavior.
“Itch sensation plays a key role in detecting harmful substances, especially those that have attached to the skin,” one of the Chinese researchers Yan-Gang Sun says. “As itch leads to scratching behavior, this allows the animal to get rid of the harmful substances.”
If an itch lasts more than a month, it’s probably time to see a doctor. Most people are reluctant to do so for a minor itch, and resort to over-the-counter remedies, which are too weak to have an effect, Keahey says.
“When the itch begins to affect quality of life — such as sleep — or is associated with a disfiguring rash, people will start to make their way into the dermatologist’s office,” he says.
Kim says there are numerous therapies, but the best ones depend on the nature of the itch: “Dry skin is best helped with moisturizers, whereas if you have eczema, certain anti-inflammatory drugs have better anti-itch properties than others.”
As for my “phantom” itch, both Keahey (who is my dermatologist) and Kim believe I probably have a fairly common ailment called notalgia paresthetica, which shows up as an itch but really involves the nerves.
“We think the nerves that relay sensation from your back become damaged or dysfunctional, causing you to itch,” Kim says. “You’re right, it is a bit of a phantom itch because there’s no primary stimulation in the skin. Rather, the nerve itself is misfiring. It’s precisely what the classic ‘back scratcher’ was invented for.”
Skin rashes turned out to be signs of serious problem
Doctors thought he just had jock itch. Then it spread.
“,”author”:”Marlene Cimons”,”date_published”:”2019-05-10T00:00:00.000Z”,”lead_image_url”:”https://www.washingtonpost.com/resizer/as8o7e_lM6U31ifAcktDNIdeCTk=/1440×0/smart/arc-anglerfish-washpost-prod-washpost.s3.amazonaws.com/public/QZU26ZDSPMI6TEZRGC6FQNXURY.jpg”,”dek”:null,”next_page_url”:null,”url”:”https://www.washingtonpost.com/national/health-science/when-to-start-worrying-about-a-chronic-itch/2019/05/10/cf52ac42-7016-11e9-8be0-ca575670e91c_story.html”,”domain”:”www.washingtonpost.com”,”excerpt”:”There are hundreds of reasons people scratch. Some are minor; some are signs of illnesses.”,”word_count”:905,”direction”:”ltr”,”total_pages”:1,”rendered_pages”:1}
Definition of itch
/ ɪtʃ /SEE SYNONYMS FOR itch ON THESAURUS.COMto have or feel a peculiar tingling or uneasy irritation of the skin that causes a desire to scratch the part affected: My nose itches.to cause such a feeling: This shirt itches. Informal. to scratch a part that itches.to have a desire to do or get something: to itch after fame.
to cause to have an itch: His wool shirt always itches him. Informal. to scratch (a part that itches): to itch a mosquito bite.to annoy; vex; irritate: Her remarks itched me.the sensation of itching.an uneasy or restless desire or longing: an itch for excitement.
a contagious disease caused by the itch mite, which burrows into the skin (usually preceded by the).before 900; (v.) Middle English (y)icchen, Old English gicc(e)an; akin to German jucken, Dutch jeuken; (noun) Middle English (y)icche, Old English gicce, derivative of the v.
italy, itapetininga, itar tass, itasca, itc, itch, itch for, have an, itch mite, itching, itchy, itchy palmDictionary.com Unabridged the Random House Unabridged Dictionary, © Random House, Inc.
2020yearning, impulse, craving, hankering, ache, yearn, crave, thirst, hanker, crawling, tickle, rawness, irritation, creeping, psoriasis, prickling, itchiness, eroticism, urge, restlessness
LIBRA Your palms may itch, signaling a cash infusion is on the horizon.
Horoscopes for June 5-11, 2011|Starsky + Cox|June 4, 2011|DAILY BEAST
My hands and wrists suddenly began to smart and itch in a most unaccountable manner.
A Year in the Fields|John Burroughs
Wit, lad, is a catching thing, the itch or the sweating sickness.
The White Company|Arthur Conan Doyle
No wonder I itch so much as I do, to get at these amours—They are the choicest morsel of my whole story!
The Life and Opinions of Tristram Shandy, Gentleman|Laurence Sterne
The queen, but half-dressed, was a prey to the itch and other disgusting maladies.
The Human Race|Louis Figuier
His Viol has the effect of a Scotch Fiddle, for it irritates his hearers, and puts them to the itch.
an irritation or tickling sensation of the skin causing a desire to scratchany skin disorder, such as scabies, characterized by intense itching(intr) to feel or produce an irritating or tickling sensation(intr) to have a restless desire (to do something)not standard to scratch (the skin)itching palm a grasping nature; avaricehave itchy feet to be restless; have a desire to travelitchy, adjectiveitchiness, nounOld English gīccean to itch, of Germanic originCollins English Dictionary – Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012An irritating skin sensation causing a desire to scratch.Any of various skin disorders, such as scabies, marked by intense irritation and itching.To feel, have, or produce an itch.The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.