Psychological factors in skin diseases: stress and skin: facts and controversies.

Psychological stress (PS) has long been related to many common skin diseases and conditions, thought to be the cause of their onset or aggravation. Although clinical experience is often in concordance with this notion, apparently scientific proof can sometimes be challenging rather than straight forward. Although many data have been published, it appears that not enough good statistical evidence exists to support them. The difficulty in validating beyond a doubt the stress-skin interactions has rendered some skepticism among physicians. The gap between clinical expertise and problematic clinical research data has led scientists to bypass the need to tackle the question directly by searching the evidence in basic science.