Does urea beat a plain moisturiser in ichthyosis?

Fourteen people with ichthyosis vulgaris applied a 7.5% urea cream to one side of the body and an identical cream without urea to the other, twice daily for four weeks, with neither they nor the assessors knowing which was which. Measurements were taken in a climate-controlled room. On the arms, the two creams performed the same. On the legs, where the scaling was heavier, the urea side did significantly better on both scaling scores and hydration. The authors' own conclusion is the useful one: urea may only beat a plain moisturiser when the symptoms are genuinely severe. The study is small, but it is the only one of its kind — the authors note that in the fifty years to 2020, only five studies compared urea cream against any control at all.