What it does
A vasoconstrictor that reduces puffiness, depuffs under-eyes, and gives skin a temporary tightening effect. Also antioxidant.
Best for
Puffy eyes, neck creams (where it adds visible tightening), and de-puffing morning routines.
The full picture
Caffeine is a short-acting vasoconstrictor: it temporarily reduces blood vessel diameter in the skin, which decreases puffiness and gives a tight, depuffed look. It is also a useful topical antioxidant. The effect is real but temporary (a few hours). Caffeine shows up most often in eye creams and neck creams where the perceived tightening matters most for the area. It does not stimulate long-term collagen production the way peptides and retinoids do.
Evidence
Topical caffeine reduces skin redness and supports antioxidant defense in skin cells.
Read the source: PubMed: topical caffeine for skin ->