What is causing that itch?

Nov 4, 2022, 08:17 AM by Dr. Sally Robinson

Everyone knows what an itch is.  We watch all sorts of mammals itch.  It is a curious thing that an itch is very irritating but scratching itch is pure pleasure.  Ogden Nash said that “happiness is having a scratch for every itch”.  Just think on how satisfying it is when someone scratches that place on your back you can’t reach.

An itch is an important sensation that works with other skin sensations of touch, pain, vibration, cold, and heat to protect the skin.  The sensation of the itch is caused by the stimulation of the specialized nerve cells called C-fibers which are identical to those fibers associated with the sensation of pain.  They function differently than pain fibers and only convey the itch sensation.  When stimulated on the skin they carry the signals to the spinal cord and then to the brain which then generates a scratching or rubbing reflex.  The scratching and rubbing interfere with the itch sensation by stimulating various pain and touch receptors. The scratching helps relieve the itch temporarily but may cause further irritation and tearing of the skin.

Another curious thing is that the sensation can sometimes exist when there are no itch fibers such as with an amputated limb itching.  So far the treatment of phantom limb itch or pain is hard to treat.  Actually, treatment for the itch is still complicated after over a century of trying to find relief.  There is no single effective anti-itch treatment.  There are lotions and creams, antihistamines, aspirin, and ultraviolet light.

Children have multiple reasons for having chronic itch and treatment frequently depends on determining what is causing the itch.  The first one that comes to mind is allergic reactions to such things as food, insect bites, pollen, and medicines.  Insect bites can be by mosquitoes or scabies or lice each requiring a different treatment. Another parasitic cause of itching in children is pinworms.  This itching is usually located around the anus and requires specific treatment for the parasite.

 Also common are skin conditions such as eczema, psoriasis, and dry skin.  Treatment for these conditions would be cold compresses, moisturizing lotions, lukewarm or oatmeal baths, lotions, and antihistamines.  It is recommended to avoid scratching, avoid perfumed soaps and bubble baths, and avoid irritating fabrics. (Gilda Radner is quoted saying “I base most of my fashion taste on what doesn’t itch.)  It is suggested that clothing should be loose-fitting and natural fabrics.  If possible keep the house cool and humid.

Rarely is itching a result of serious problems but thyroid, kidney, and liver disease, even cancer can have itching as a side effect.  If itching lasts longer than three days and is not caused by a recognizable problem a doctor should be consulted.

by Sally Robinson, MD Clinical Professor
Keeping Kids Healthy
Published 10/2022

Also See:  UTMB Pediatrics - Pediatric Primary Care