Praise be to Allah.
Urea is an organic compound excreted by the human body and the bodies of many other animals, and it can be manufactured synthetically for use in various products, such as animal feed, fertilizers, pharmaceutical products and plastics.
The human body excretes urea in order to get rid of excess nitrogen. Urea is formed mainly in the liver and is mostly excreted in urine.
Urea was the first organic compound to be produced synthetically from inorganic substances. In 1828 CE, the German chemist Friedrich Wöhler synthesized urea by heating an aqueous solution of ammonium cyanate, which is an inorganic compound. Wöhler’s work helped to refute the belief that organic compounds could not be formed except in living beings.
See: al-Mawsoo‘ah al-‘Ilmiyyah al-‘Aalamiyyah.
There is nothing wrong with using this pure (taahir) synthetic product, because in principle, things are pure.
Based on that, there is nothing wrong with using it in skin moisturizers or body lotions.
Even if we assume that the urea is extracted from urine – which is unlikely – if it comes from the urine of an animal whose meat may be eaten – such as camels, cattle, sheep and horses – there is nothing wrong with it, because their urine is taahir (pure).
But if it comes from human urine or the urine of animals whose meat should not be eaten, then it is najis (impure). But if other substances are added to it that take away the characteristics of impurity, in such a way that its taste, colour or smell no longer remain, then it becomes pure, according to the more correct scholarly view, and it is permissible to use it in creams and so on, on condition that they cause no harm.
And Allah knows best.