Alkaloid found in coffee, tea, and kola nuts. Caffeine is the chief stimulant in beverages such as coffee and tea. It’s often included in skin-care products with claims that it will reduce cellulite or puffy eyes. Given the prevalence of Starbucks stores all over the world, it would be great news for women’s thighs and eyes if that were the case, but, unfortunately, caffeine’s results in this regard are mixed.
Caffeine and its constituents are thought to convey antioxidant benefits when consumed orally. Studies have looked at oral consumption of caffeine-containing beverages followed by exposure to UVB light (the kind that causes sunburn and skin tumors) and found that compared with those who drank decaffeinated beverages, the drinks with caffeine conveyed a protective benefit (Sources: Journal of Investigative Dermatology, July 2009, pages 1,611–1,613; Photochemistry and Photobiology, March-April 2008, pages 330-338; and >em>Carcinogenesis, August 2005, pages 1,465–1,472).
Applied to skin, caffeine may have anti-inflammatory properties (Source: Food Chemistry and Toxicology, September 2012, ePublication). It has a constricting effect on skin, which can help reduce redness but may also be irritating. It’s not a slam dunk for facial redness, and in fact some may find it worsens the problem.
Caffeine’s popularity in products related to cellulite is due to its distant relationship to aminophylline (a pharmaceutical once thought to reduce cellulite), which is a modified form of theophylline (Source: Yale New Haven Health Library, Alternative/Complementary Medicine, www.yalenewhavenhealth.org), and caffeine contains theophylline (Source: Progress in Neurobiology, December 2002, pages 377–392). There is no substantiated research proving theophylline can affect cellulite, but researchers have disproved aminophyilline’s claimed impact on cellulite. The second reason caffeine may show up in cellulite products stems from research showing it to have benefit for weight loss, but that’s only when you drink it, not when you rub it on your thighs.
There are only two studies showing caffeine to have benefit for reducing cellulite. One was conducted by Johnson & Johnson, which owns the RoC and Neutrogena brands, both of which sell (or once sold) cellulite creams that contain caffeine. The other was conducted by cosmetics ingredients manufacturers that sell anti-cellulite compounds (Source: Journal of Cosmetic Science, July–August 2002, pages 209–218). There is no independent research showing that caffeine can provide any benefit for treating cellulite.
When it comes to puffy eyes, there is no research indicating caffeine can have this benefit when applied topically. However, caffeine does have potential as an antioxidant, so it isn’t a wasted ingredient in skin-care products (Sources: BMC Complementary and Alternative Medicine, March 2006, http://www.biomedcentral.com/1472-6882/6/9; Bioscience, Biotechnology, and Biochemistry, November, 2005, pages 2219–2223; Obesity Research, July 2005, pages 1195–1204; and Sports Medicine, November 2001, pages 785–807).