Itch (Latin:<unk>  is defined as an unpleasant sensation that evokes the desire or reflex to scratch. Itch has many similarities to pain and both are unpleasant sensory experiences but their behavioral response patterns are different. Pain creates a reflex withdrawal while itch leads to a scratch reflex. Unmyelinated nerve fibers for itch and pain both originate in the skin, however information for them are conveyed centrally in two distinct systems that both use the same peripheral nerve bundle and spinothalamic tract.
Historically, the sensations of itch and pain have not been considered to be independent of each other until recently where it was found that itch has several features in common with pain but exhibits notable differences. The physiological mechanisms of itch are currently poorly understood and this is mainly due to the lack of animal models of itch.<unk>  stimuli mostly create the same reactions as noxious stimuli in experimental animals, but humans are capable of discerning the distinct features of itch and pain. Therefore human studies have provided most of the information regarding the processing of<unk>  stimuli.
Pruritis
Arthralgia
Hematuria
Scalp rash
Dermatitis
Dysuria
Diaper rash
Keratitis