What it is
Allantoin is a small nitrogen-containing molecule (C4H6N4O3), chemically a diureide of glyoxylic acid, used in cosmetics as a soothing, skin-conditioning, and skin-protecting agent. It is valued for softening and smoothing skin and is associated with calming and skin-comforting effects, which is why it appears in many sunscreens and after-sun and sensitive-skin products. It occurs naturally in comfrey and in the urine of most mammals, where it forms from the oxidation of uric acid. In skincare it is appreciated for being gentle and broadly compatible with other ingredients.
Safety & warnings
Allantoin has a long record of gentle use and is widely chosen for sensitive-skin and soothing formulations, with ingredient references describing it as non-irritating and suitable for reactive skin. It is typically used at low percentages (for example around 0.5 percent), and there are no notable sensitization concerns reported for the purified cosmetic ingredient.
Origin & sourcing
Allantoin occurs naturally in comfrey root and leaves and in mammalian urine, but the material used in cosmetics is almost always produced synthetically. The synthetic route is based on the oxidation of uric acid, yielding a pure, consistent ingredient that is compatible with cosmetic raw materials.
History
The compound is named after the allantois, an embryonic structure in mammals. It was first isolated around 1800 by Michele Francesco Buniva and Louis Nicolas Vauquelin, identified in allantoic fluid by Jean Louis Lassaigne in 1821, and in 1837 Friedrich Wohler and Justus Liebig synthesized it from uric acid and established its modern name.
Questions everyone asks
What does allantoin do in a sunscreen?
It is added as a soothing, skin-conditioning, and skin-softening agent to help keep skin feeling calm and comfortable.
Is allantoin natural?
It occurs naturally in comfrey and mammalian urine, but the cosmetic ingredient is almost always made synthetically by oxidizing uric acid for purity and consistency.
Is allantoin safe for sensitive skin?
It is well known as a gentle, soothing ingredient and is commonly used in products formulated for sensitive and reactive skin.