What it is
Citrulline is a non-protein amino acid found in many plants and present in the body's metabolic pathways. In cosmetics it is used as a water-soluble skin-conditioning and humectant ingredient that helps support skin hydration. It is typically included in the water phase of serums, lotions, and sun care products at modest levels.
Safety & warnings
Citrulline is an amino acid generally regarded as well tolerated and non-irritating in cosmetic use, with low sensitization potential.
Origin & sourcing
Can be derived from plant sources such as watermelon or produced by fermentation or synthesis; the amino acid also occurs naturally in the body.
Questions everyone asks
What is citrulline?
It is a naturally occurring amino acid, found in watermelon among other sources, used in skincare as a hydrating, conditioning ingredient.
Does it provide sun protection?
No. It is a humectant and skin-conditioning amino acid, not a UV filter.