Why is renal failure a contra-indication if Urea doesn penetrate further than the epidermis ?
Urea is considered to penetrate the epidermis, re-hydrating it. However, if penetration continued as far as the dermis, systematic absorption into blood vessels is a theoretical possibility. Patients with chronic renal failure are already at risk from increased levels of Urea in the blood causing uraemia (a toxic build up in levels of Urea in the blood). Although the risk is theoretical, as there are no reported cases we recommend erring on the side of caution.
