What it is
Polygonum Cuspidatum Root Extract comes from the root of Japanese knotweed and is a well-known botanical source of resveratrol and related polyphenols. In skincare it is used mainly for its antioxidant activity and to help condition and calm the appearance of the skin. It serves as a supporting active in sunscreens rather than as a UV filter.
Safety & warnings
This extract is generally well tolerated at the low levels used in cosmetics, with sensitization being uncommon. Like other botanicals its composition can vary between suppliers, and rare individual sensitivities are possible. It is not a recognized fragrance allergen and is not considered comedogenic.
Origin & sourcing
Botanical extract from the roots of Polygonum cuspidatum (Japanese knotweed), typically prepared with water, glycols, or alcohol.
Questions everyone asks
Why is Japanese knotweed extract used in skincare?
It is a plant source of resveratrol and other polyphenols, so it is included mainly for antioxidant and skin-conditioning benefits.
Does it provide sun protection?
No. It is a supporting antioxidant botanical and is not a UV filter.