In general, pruritus involves activation of the pruriceptors of specialized nerve cells called C-fibers. These C-fibers are identical to those associated with the sensation of pain, but they are functionally distinct and only convey the itch sensation—they comprise about 5 percent of the total C-fibers in human skin. When stimulated superficially on the skin, these C-fibers carry signals along the nerve to the spinal cord and on to the brain, where they are processed, generating a scratching or rubbing reflex response. Scratching and rubbing then interfere with the sensations arising from pruriceptors by stimulating various pain and touch receptors in the same areas. Though it is helpful in relieving the itch, scratching offers only temporary relief and may cause the skin to become further irritated and possibly tear, which could result in an infection.
Despite approximately a century of pruritus research, there is no single effective antipruritic treatment, but several topical and orally-administered agents are available that suppress itching in certain clinical settings. These agents include lotions and creams (such as calamine and hydrocortisone), antihist