Acetyl Tetrapeptide-5

Overview

Acetyl Tetrapeptide-5 is a synthetic four-amino-acid peptide designed specifically for the delicate skin around the eyes. Unlike most peptides which target collagen synthesis, this one has two related but distinct effects on the eye area: it reduces puffiness by limiting capillary leakage and water retention in the under-eye, and it interferes with the glycation reaction (the cross-linking of sugars with skin proteins) that contributes to dark circles and skin stiffness.

It is supplied as a clear water-thin liquid, pre-diluted in water and glycerin to a peptide content of around 0.05%. The trade-name version sold to brands is one supplier’s blend; the INCI you put on your label is the tetrapeptide name above.

Shelf life is 12-18 months stored cool and dark. It is fully water-soluble and has no scent.

Published clinical data shows measurable reduction in under-eye puffiness and dark circles after 4-8 weeks of twice-daily use. It is one of the few peptides that targets the eye area specifically rather than as a general anti-aging claim.

What it does in a formula

The peptide acts on two pathways. First, it reduces vascular permeability — the leakiness of the very fine capillaries under the eye that contributes to morning puffiness and the bluish look of dark circles. Second, it interferes with the binding of sugars to skin proteins, a process called glycation that over years makes skin stiffer, more yellow, and more prone to settled dark patches.

It is functionally invisible in a formula — no scent, no color, no texture impact. It plays well with caffeine (a common eye-area co-ingredient), niacinamide, and other peptides.

How to use

Cool-down only, below 40 C. Stir in gently after the emulsion has cooled. Heat degrades the active over time.

Usage rates by product type (referring to the supplier blend, not pure peptide):

• Under-eye serums and creams: 3-5%
• Eye contour gels: 3-5%
• Eye masks (leave-on): 4-5%
• Anti-aging face serums (broader claim): 2-3%

Effective minimum is around 3% of the blend; standard use is 4%. Above 5% the cost climbs without proportional benefit.

Best for / Worst for

Best for: under-eye puffiness, mild dark circles caused by capillary leakage, mature skin, eye creams positioned for “fatigue” or “tired eyes,” formulators wanting a peptide that targets a visible problem rather than long-term collagen support.

Worst for: structural dark circles (genetic pigmentation or shadowing from bone structure — the peptide cannot fix these), anhydrous balms, low-pH formulas.

Common pitfalls

Combining with too much caffeine. Both ingredients are de-puffing actives. Stacking them at maximum dose in the same formula does not double the effect and can dry the area. Use moderate amounts of each.

Cooking it. Always cool-down. Heat-phase addition degrades activity.

Expecting it to fix all dark circles. Dark circles have several causes — pigment, shadow from anatomy, fatigue-related vascular pooling. The peptide helps the third type. The others need different approaches.

Combining with low-pH AHA exfoliants in the same product. Best at pH 4.5-6.5.

Substitutes

• Caffeine — gentle de-puffing active for the eye area, non-peptide and inexpensive.
• Palmitoyl Tetrapeptide-7 — anti-inflammatory peptide also used for tired-looking eyes.
• Niacinamide — broad-spectrum active for tone evening and barrier.
• Acetyl Hexapeptide-8 — for the dynamic-line dimension of eye aging (crow’s feet).