Why Do We Itch?

Author: Renee Cao

Editors: Kira Tian and Liane Xu

Artist: Daelah Nicholas

Did you know that our skin is the only body part that experiences pruritus and pain at the same time—hold on, what is pruritus? Read on to find out!

Why do we always want to scratch mosquito bites? The answer is pruritus, or commonly known as an itch. When our skin or nerve cells start getting irritated, we develop the urge to scratch—a vital sensory and self-defense mechanism. Pruritus is a common symptom of many skin disorders. It is stimulated by pruriceptors, nerve endings that sense itches. Inflammation and damage to the skin, mucous, or eye membranes all stimulate mechanical, thermal, and chemical agents that cause itching.

Itches are caused when C-fibers, specialized nerve cells, are activated by their pruriceptors. When C-fibers are stimulated, they bring signals from the nerve to the spinal cord, and then to the brain, resulting in a scratching reflex. The scratching interferes with the sensations caused by the pruriceptors, and thus temporarily relieving an itch. When this happens, low-level pain signals are sent to the brain, distracting the brain and releasing serotonin. However, scratching too much can make the skin become more irritated. It might then tear up and develop a lasting infection. In fact, our skin is the sole part of our bodies that experiences itchiness and pain at the same time. Joints, muscles, and organs can only feel pain.

Itches can be caused by infections such as lice, insect bites, scabies, shaving, and herpes. It can also be caused by environmental factors and allergies such as poison ivy. Skin disorders like dandruff, sunburns, chickenpox, athlete’s foot, and scabs are also common causes of itching.

Luckily, there are several remedies for itching. For minor itches, the simplest way would be not to scratch in the first place, as scratching further intensifies the itching. Placing something cold on top of the itch is also a useful remedy. For more severe itches, use cream or lotion with calamine and hydrocortisone. Other treatments include antihistamines, opioid antagonists, and aspirin.

 

Citations:

“Why and How Do Body Parts Itch? Why Does It Feel Good to Scratch an Itch?” Scientific

American,

https://www.scientificamerican.com/article/experts-why-we-itch-and-scratch/.

“Why Do We Itch? Why Does Scratching Feel Better?” Healthline, 26 Feb. 2020,

https://www.healthline.com/health/why-do-we-itch.

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