Adenosine
A gentle, well-tolerated add-on active (a naturally occurring nucleoside) with real but modest evidence for smoothing fine lines over a couple of months.
What it does
Adenosine is a nucleoside your cells already use for energy and signaling. Applied topically it is studied as a mild active for fine lines and skin smoothness: a placebo-controlled trial using objective skin-surface measurement found significant smoothing of periorbital and glabellar (frown-line) wrinkles over about eight weeks. The effect is subtle and the evidence base is narrower than for retinoids or vitamin C, so adenosine is best thought of as a gentle, low-irritation supporting ingredient — often paired with stronger actives — rather than a do-it-all answer for aging concerns. It is generally very well tolerated, which is part of its appeal in sensitive-skin and after-procedure formulas.
The evidence, graded
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Pairs worth knowing
Browse all 668 ingredients — grouped by what they do, each with whatever evidence we can cite.