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Why We Itch (And How to Stop It)

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They’re itchy, they’re scratchy, and they’re not going away just because mosquito season is coming to a close. Everybody itches, but we all scratch for different reasons whether it be bug bites, rashes, allergic reactions, or that chunky wool sweater grandma gave us. There are many different triggers that cause those annoying irritations, so here we look at four reasons we itch, how and why they occur, and what we can do to stop them.

Itchy and Scratchy Show — The Need-To-Know

Photo by Jess Ivy

If scratching is bad for us, then why do we do it so impulsively? Our bodies are filled with nerves, and some nerve fibers are sensitive to touch, pain, or itch. “Itching” nerve fibers are activated when they detect histamine.

During allergic reactions, our bodies release a protein called “histamine,” which is transferred to the brain via the spinal cord. Histamine causes inflammation and is meant to help the body fight infections (for example, from bites or abrasions). Multiple areas of the brain, including those that control emotional, sensory and motivational patterns, are all activated by the itch sensation. [1]. Antihistamines disable the protein from telling the brain about the itch and help us stop scratching.

But there’s a reason that scratching feels so good. A study from the British Journal of Dermatology found that scratching reduces activity in the anterior and posterior cingulated cortices in the brain, causing pleasure. But most dermatologists — and common sense parents — suggest to keep scratching to a minimum to prevent skin damage [2].

While we all scratch to relieve an itch, itches can be caused by skin conditions, irritants, allergies, plants and insect bites. Here’s why they itch and how to treat them.

Why We Itch

Skin conditions

How It Happens: A thick skin is no match for these ailments. Skin conditions such as eczema or psoriasis affect specific areas and come with a rash. Babies are the most common sufferers from these conditions, with most symptoms usually fading with age.

How To Soothe: A good skin care regime is important in treating skin conditions, as are mild soap and moisturizer. Sometimes bleach baths work (but only with very small bleach-to-water ratios and after a consultation with a doctor).  Again, scratching is ill-advised — some sufferers wear gloves to resist the temptation.

Irritants and allergic reactions

How It Happens: This is a pretty wide-encompassing category that includes everything from grandma's itchy wool sweater to soaps and food allergies. Not all reactions are created equal, however.

A body has an allergic reaction when it perceives an “invader” (for example: pet dander or pollen) and will cause symptoms (runny eyes, scratchy throat) to defend itself. An irritant, however, only affects the body through touch. People can come into contact with an irritant and have a reaction, but still not be allergic — the only way to truly know is to be tested by a doctor for the specific substances [3].

How To Soothe: Topical creams and antihistamines such as Benadryl can provide relief, but home remedies such as lemon juice (fresh, not bottled), which contains anesthetic and anti-inflammatory properties, can also reduce itching. The chemicals in lemon juice turn to alkaline in the body, reducing swelling [4].

Plants

How It Happens: No camping trip is complete without a painful rash, most likely from poison ivy, oak or sumac. Urushiol, a poisonous oil in the plants most likely to seal wounds and defend against bacteria, causes a blistery rash that appears at least 12 hours after contact and can last for several weeks.

How To Soothe: As the saying goes: “leaves of three, let them be.” But if not, rinse the affected area and wash all clothes that came into contact with the poisonous plant. Urushiol can stay active on surfaces for up to five years so make sure to scrub like crazy. Cool showers, calamine lotion, oatmeal (thank you, Mr. Quaker) or baking soda baths can also soothe the skin.

The cure for poisonous plants, however, might be even closer than the kitchen cabinet. The Jewelweed plant (or the “Touch-me-not,”) often grows near poison oak and ivy and can counteract the itch-inducing urushiol before the itch even appears. Ironic name for a helpful piece of greenery!

Bug bites

How It Happens: A mosquito slurping blood leaves something behind — her saliva. This saliva causes bodies to release histamines in response, causing that itchy sensation. Over time, people can build up a tolerance to the saliva, which explains why children have more of a reaction than adults.

How To Soothe: Antihistamines help but a damp green tea bag can also do the trick. The cool temperature of the bag provides relief while the ingredients in the tea decrease inflammation. For a quick fix, try putting scotch tape over the bite to prevent scratching, and help skin heal faster.

For creatures that inject venom, such as bees, snakes or spiders, wetting the bite and rubbing a 9-volt battery against it will stop the venom and pain. The electric current deactivates the venom, and the water elevates conductivity in your skin, increasing the current.

This list is by no means exhaustive but merely scratches the surface. If the itching sensation has taken over while reading this, don’t worry — doctors are researching this phenomenon and believe it’s normal to want to scratch. So if all (and we mean all!) else fails, go ahead and scratch, but just a little.

What get's you scratching? And how do you fight the urge to itch? Let us know your tips in the comments below.

Works Cited

  1. Itch and the brain. Pfab, F., Valet, M., Napadow, V., et al. Department of Radiology, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA. Chemical immunology and allergy, 2012;98:253-65.
  2. Histamines and Anti-Histamines in Atopic Dermatitis. Buddenkotte, J., Maurer, M., Steinhoff, M. Advances in experimental medicine and biology. 2010;709:73-80.
  3. Chapter 2: Skin testing in allergy. Carr, T.F., Saltoun, C.A. Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL. Asthma and Allergy Proceedings: the official journal of regional and state allergy societies, 2012 May-June;33 Suppl 1:6-8.
  4. Anti-inflammatory effect of lemon mucilage: in vivo and in vitro studies. Galati, E.M., Cavallaro, A., Ainis, T., et al. Pharmaco-Biological Department, University of Messina, Italy. Immunopharmacol Immunotoxicol. 2005;27(4):661-70.