Occupational contact dermatitis: known knowns and known unknowns.

It is only by recognizing what we know that we know, and being cognizant of the things that we know that we don't know that clinicians and the health profession are able to deliver quality care to patients. Traditional learning methods can sometimes perpetuate unappraised and unfounded beliefs and practices. Evidence-based practice requires robustly conducted systematic reviews and evidence-based guidelines. There have only been three systematic reviews of occupational contact dermatitis. These inform us of what we know we know and what we know that we don't know. We know which agents cause allergic and irritant occupational contact dermatitis, and we know the occupations that present the greatest risk. We know that conditioning creams are helpful in the prevention and management of the disease, and we know that we don't know the optimal frequency of application. We know that prework creams are not universally effective. We know that avoidance of exposure can help to improve symptoms in those who have developed dermatitis, but we know that we don't know if earlier identification and earlier avoidance of exposure produces better outcomes. Most importantly, we know that there is a need for better research conducted in occupational rather than experimental settings and with contact dermatitis rather than subclinical findings as an outcome measure.