Acetyl hexapeptide-8

It belongs to the group of so-called neurotransmitter-inhibiting peptides, marketed on the idea of temporarily softening small facial muscle contractions at the skin's surface. It is a cosmetic ingredient, not an injectable, and it is not comparable in effect to botulinum toxin, whatever the marketing shorthand "botox in a jar" suggests.

Published support is limited and largely manufacturer-led, and the peptide is a large, water-loving molecule with limited penetration. Any visible change tends to be gradual, subtle and dependent on continued use; it concerns how fine expression lines look rather than the structure of the skin.

It is water-soluble and usually appears in serums, eye products and moisturisers, and is generally well tolerated, including by sensitive skin. It layers easily with niacinamide, hyaluronic acid and moisturisers. If you are pregnant, breastfeeding or using prescription treatments, check with your doctor before adding new actives, and patch test anything new.