3% Redensyl, 4% Anagain & 5% Capilia Stem Cell Complex Advanced Hair Growth Serum

Niacinamide — Vitamin B3 — a broadly-tolerated all-rounder that strengthens the skin barrier, evens tone and helps regulate oil. The strength is not printed, so we cannot judge the dose; that counts against the brand. Works from ~5%. OTC cap 10%. Give it 8–12 weeks for tone. Suits all skin types. One of the best-tolerated actives there is — fine for every skin type, and especially handy for oil and uneven tone.

Caffeine — Constricts surface blood vessels, so it temporarily reduces under-eye puffiness. Honest limit: the effect is temporary, and the evidence on dark circles is modest — it won't erase pigment-based circles. The strength is not printed, so we cannot judge the dose; that counts against the brand. Works from ~3%. OTC cap 5%. Suits all skin types. A temporary de-puffer for the under-eye — low-risk for every skin type. Just don't expect it to erase pigment-based dark circles.

Niacinamide: a review on dermal delivery strategies and clinical evidence ›

Niacinamide - mechanisms of action and its topical use in dermatology ›

Mechanistic Basis and Clinical Evidence for the Applications of Nicotinamide (Niacinamide) to Control Skin Aging and Pigmentation ›