For your skin
Tightens and brightens the under-eye area, reducing the look of puffiness by constricting tiny blood vessels. Best deployed in eye creams.
Want the science? Keep reading ↓Mechanism of action
Methylxanthine that vasoconstricts capillaries, inhibits phosphodiesterase to stimulate lipolysis, and scavenges free radicals.
Why we tier this moderate
5 cited papers across 2 countries. The mechanism is well-described and there's at least one controlled trial in the literature, but we tier this Moderate rather than Strong to stay honest about how many specific papers we cite directly.
Cited research
Elias M et al., Caffeine in Skincare: Its Role in Skin Cancer, Sun Protection, and Cosmetics, Indian Journal of Dermatology 2023;68(5):546-550 — evidence for topical caffeine's photoprotective, antioxidant, and anti-cellulite roles
Gherardini J et al. (Germany), Transepidermal UV radiation of scalp skin ex vivo induces hair follicle damage that is alleviated by the topical treatment with caffeine, International Journal of Cosmetic Science 2019;41(2):164-182 — topical caffeine reduced UV-induced hair follicle cytotoxicity and premature catagen entry in ex vivo human scalp
Luo L, Lane ME (UK), Topical and transdermal delivery of caffeine, International Journal of Pharmaceutics 2015;490(1-2):155-64 — review of caffeine physicochemistry and formulation strategies for skin permeation supporting cosmetic and transdermal use
Herman A, Herman AP, Caffeine's mechanisms of action and its cosmetic use, Skin Pharmacology and Physiology 2013;26(1):8-14 — vasoconstriction, antioxidant, lipolysis; 3% topical caffeine penetrates skin barrier effectively
Lupi O et al., Evaluation of the effects of caffeine in the microcirculation and edema on thighs and buttocks using orthogonal polarization spectral imaging and clinical parameters, Journal of Cosmetic Dermatology 2007;6(2):102-107 — 7% topical caffeine significantly reduced thigh/hip circumference
Sources: 10 clinical journals and regulatory databases across the US, EU, Korea, Japan, and China. Every entry points to a specific document. See methodology for the full list and what each outcome label means.