Scratching Addendum

Since I ruled out scratching to stop an itch--see last Friday’s blog post, Scratch That Itch?--I feel obligated to highlight some other approaches. I want to be careful here. I’m talking about temporary relief of simple itches, such as my winter, dry skin itch. If you’ve an itch that persists or if there’s any chance it’s caused by a medical condition, don’t hesitate to consult a health care professional. OK?

Recommended self-care products that I’m sure you’re familiar with and for which any pharmacist would help are moisturizing or nonprescription anti-itch creams or lotions.

The simplest home remedies are applying ice packs or cool, wet compresses or taking a cool shower or bath. Hot water makes it worse, if I could only resist.

Many other home remedies have been recommended. I don’t follow this sort of thing and knew almost none, but I expect my wife knows most of them. Maybe one or two of the following are new to her and possibly to you, too. Commercial products are widely available.

Baking Soda or Oatmeal: Apply either product as a paste or add 1 cup baking soda or 1 or 2 cups colloidal or finely ground oatmeal to a bath (lukewarm water). (Photo of dog enjoying an oatmeal bath is from multiple websites)

Essential Oils or Herb Leaves: Apply directly or add to a bath the essential oil of, for example, basil, chamomile, clove, lavender, peppermint, rosemary or thyme. Or rub the skin with leaves, or a cooled tea made from leaves, of either basil, mint, thyme or tulsi (holy basil). (Photos are from multiple websites)

Oil Therapies: Apply olive, almond or sesame oil before showering. Another recommendation is to apply a thick layer of coconut oil and cover it before heading to bed. (Photo from multiple websites)

Apple Cider Vinegar: Apply with a cotton swab or cloth or add 2 or 3 cups to bath water. (Photo from multiple websites)

Lemon Juice: Apply juice and allow to dry. (Photo from multiple websites)

Aloe Vera: If you have the plant, cut a piece, squeeze or scoop out the gel and apply it. (Photos are from multiple websites)

Milk: Apply with a cloth. (Yes, you can take a bath in milk, but that seems a bit much unless you’re a movie star or you really, really like milk.) (Photo from multiple websites)

Honey: Heat lightly, apply and wash off after about 15 minutes. (Photo from multiple websites)

Although their preparation is more involved, various mixes have been recommended, such as honey with olive oil and beeswax or juniper berries with cloves and beeswax. So too have certain clays, though those might not be readily available. Along with treatments, it’s also recommended to wear smooth-textured, loose cotton clothing, use soaps without dyes or perfumes, and…well, like treatments, the list goes on.

P.S.

Example websites that address itchy skin:
-www.mayoclinic.org/diseases-conditions/itchy-skin/basics/tests-diagnosis/con-20028460
-www.medicinenet.com/itch/article.htm#itch_facts
Example websites that have recommended home-remedies (lots of redundancy):
-www.onegoodthingbyjillee.com/2012/11/21-home-remedies-for-dry-itchy-skin.html
-health.howstuffworks.com/wellness/natural-medicine/home-remedies/home-remedies-for-itching.htm
-gerson.org/gerpress/8-natural-remedies-for-itchy-and-irritated-skin/
-www.thehealthsite.com/diseases-conditions/natural-remedies-for-itchy-skin-p214/

Scratch That Itch?

Welcome back. I’ve got an itch. It’s not a yen. It’s a dry-skin, winter itch that I’d put lotion on if I could reach it or scratch if I didn’t know better. I don’t remember when I was told or learned that scratching itches makes them worse; it had to be a long time ago. I passed that pearl of wisdom to my offspring, of course, though they probably had to learn it themselves anyway.

Bear scratching its back from USGS
Northern Divide Bear Project video.
www.youtube.com/watch?v=uRiVkmiSiIU

Knowing the punishing consequences of scratching an itch is not the same as knowing why that happens. For that, we needed a study with 21 contributors from Washington University in St. Louis. (Several of those contributors are now elsewhere--the University of Toledo in Ohio, University of California, San Francisco and different academic and medical institutions in China.)

To learn why scratching makes itches worse, the researchers worked with mice. Although their findings hadn’t been tested with humans at the time the study was reported online, they seemed to have nailed it. They blame it on serotonin.

Serotonin

You may have heard of serotonin. It’s a neurotransmitter found in the gastrointestinal tract, platelets and central nervous system. In general, neurotransmitters activate receptors, which in turn may excite or inhibit transmission between cells. Because serotonin receptors are involved in a variety of biological and neurological processes (e.g., anxiety, appetite, memory, pain, sleep), they’re the focus of different drugs, including antidepressants and antipsychotics.

Serotonin and Itching

Scratching relieves an itch temporarily by causing minor skin pain. That pain prompts nerve cells in the spinal cord to carry pain signals instead of itch signals to the brain. The brain responds by producing serotonin to aid in pain control. That’s where the reason for scratching gets befuddled.

The researchers found that, as serotonin spreads from the brain into the spinal cord, it can do more that activate pain-sensing nerve cells. It can also activate nerve cells that affect itch intensity and thus worsen the itch.

They bred mice that lacked the genes needed to produce serotonin. These mice scratched much less than unaltered control mice when injected with a compound that causes itching. When the genetically altered mice were subsequently injected with serotonin, they scratched the same as the control mice.

Interrupting the Itch Pain Cycle

The obvious solution to reduce itching is to reduce serotonin; but since serotonin gets involved in assorted biological and neurological processes, that’s a no-no. Instead, the investigators targeted the spinal cord nerve cells that transmit itch signals. Specifically, they isolated and targeted the serotonin receptor that activates the itch-transmitting GRPR nerve cells.

Singling out the correct receptor was done by monitoring the response after injecting mice with an itch-causing compound and compounds that activated different serotonin receptors. To confirm the winning receptor, which is known as 5HT1A, they also treated mice with a compound that blocked that receptor.

Wrap Up

So what have we got? Scratching an itch causes pain, the brain produces serotonin to control the pain and the serotonin worsens the itch by activating the itch-transmitting nerve cells through the serotonin receptor. Not to worry if you didn’t get that. All you really have to remember is don't scratch that itch. Thanks for stopping by.

P.S.

Washington University study in Neuron journal:
www.cell.com/neuron/abstract/S0896-6273%2814%2900901-5
Articles on the study on Science Daily and Medical News Today websites:
www.sciencedaily.com/releases/2014/10/141030132957.htm
www.medicalnewstoday.com/articles/284655.php
Examples of other research on serotonin and pain:
2009: www.ncbi.nlm.nih.gov/pmc/articles/PMC2811866/
2014: www.cell.com/neuron/abstract/S0896-6273%2813%2901141-0
Background on serotonin: en.wikipedia.org/wiki/Serotonin