The Index · Botanical extract (Japanese knotweed)
Polygonum Cuspidatum Root Extract
Polygonum Cuspidatum Root Extract
Japanese knotweed extract used for soothing/antioxidant support in leave-on skincare; composition varies by extract.
EmergingBotanical with limited standardized clinical evidence for cosmetic endpoints.
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Japanese knotweed extract used for soothing/antioxidant support in leave-on skincare; composition varies by extract.
What it does
Often standardized toward resveratrol-related phenolics for antioxidant marketing. Extract standardization varies — grade reflects limited controlled outcome data for this exact INCI.
The evidence
Evidence grade emerging: Botanical with limited standardized clinical evidence for cosmetic endpoints. Credible chemical identity and cosmetic-use context come from CIR/SCCS/manufacturer INCI definitions and databases such as SpecialChem/PubChem[1].
How to use it
Expect this as a supporting INCI line item unless labeled as a featured active.
Evidence by claim
Graded separately; the entry grade is the best-supported claim
Japanese knotweed extract used for soothing/antioxidant support in leave-on skincare; composition varies by extract.[1]
EmergingSafety & limits
Source and region, always
all — Used in cosmetics within conventional leave-on/rinse-off levels; see cited safety literature.[1] CA US EU UK
Sources · 2
Numbered as cited in the text
- [1]SpecialChem. SpecialChem INCI profile: Polygonum Cuspidatum Root Extract. SpecialChem (2024)other
- [2]Cosmetic Ingredient Review. Plant extracts context: Japanese knotweed. CIR (2018)regulator
Revision history
18 Sept 2026Drafted by botTheSkindex Desk