N-Hydroxysuccinimide

N-Hydroxysuccinimide is used in topical brightening/anti-dark-circle products (often alongside peptides like palmitoyl tripeptide-1/tetrapeptide-7) typically around ~0.1–1%, where it functions as a reactive small molecule rather than an inert solvent. While not a classic high-irritancy active like exfoliating acids or retinoids, its chemistry and limited broad safety history in very compromised skin mean stinging or mild dermatitis can occur in reactive users, especially around the thin periocular area and in eczema-prone patients. Given the sensitive-skin context and the need to avoid underestimation, a mild irritancy score is the safest clinically aligned rating. Safety Notes: N-Hydroxysuccinimide is most commonly encountered in leave-on under-eye “dark circle”/de-puffing serums and creams (often paired with chrysin and peptides), where commercial formulas at the low end use trace-to-support levels around 0.01–0.1% to complement the blend. The majority of mainstream products cluster roughly ~0.1–0.5%, while a small number of high-strength consumer-available targeted eye treatments and boosters push total N-hydroxysuccinimide up to about 1–2% before sensorial/stability and irritation constraints become limiting. It is rarely used in rinse-off products, and when present it is typically at the low end due to short contact time and cost/benefit.