The science
The evidence in this tube has three tiers, and it helps to keep them apart. The top tier is the emollient base — jojoba, squalane, shea, avocado and rosehip oils over glycerin — whose effects on hydration, suppleness and the temporary appearance of fine lines are well characterised and not in dispute. The middle tier is caffeine, whose cosmetic mechanisms are reviewed in a 2013 paper in Skin Pharmacology and Physiology: it penetrates the skin barrier, constricts superficial vessels and has lipolytic and antioxidant activity, which together give a plausible, short-lived basis for reduced puffiness and a slight lightening of vascular shadow (https://pubmed.ncbi.nlm.nih.gov/23075568/). At nineteenth position the dose here is modest, and the brand's dermatologist-scored 22 percent puffiness figure is consistent with a light caffeine effect plus the mechanical massage Nuxe prescribes — though without a control arm it cannot be separated from either. The same panel's 36 percent dark-circle figure needs the same caveat, and a 2014 review in the Journal of Drugs in Dermatology explains why: periorbital darkness has several causes — melanin, visible vessels, shadow from a tear-trough hollow, thin skin — and only some respond to any topical, with agents like retinoids, lightening compounds and procedures carrying the evidence (https://pubmed.ncbi.nlm.nih.gov/24719068/). A humectant-emollient cream with a little caffeine can plausibly soften vascular shadow; it cannot touch pigment or structure.
The bottom tier is Alfa [3R] Technology. Alfalfa seed extract and Hemerocallis fulva extract have in-vitro data — retinoid-responsive gene activity and antioxidant capacity in cell culture — and the 'more effective than retinol' line is, by the brand's own footnote, drawn from that kind of test. No controlled human trial of either extract in a topical product was found, and both sit near the end of this list, behind the preservatives. Read symmetrically: Nuxe deserves credit for scoring one panel with a clinician instead of a questionnaire, and that credit stops at the point where 31 uncontrolled volunteers are asked to stand in for a trial.
References 2 ShowHide
- Caffeine's mechanisms of action and its cosmetic use — Skin Pharmacology and Physiology (2013)
- Periorbital hyperpigmentation: review of etiology, medical evaluation, and aesthetic treatment — Journal of Drugs in Dermatology (2014)