What is “Acetyl Tetrapeptide-2” and what is it used for?

Acetyl tetrapeptide-2 is a synthetic peptide used in cosmetics, belonging to the family of biomimetic peptides. As its name indicates, it is a tetrapeptide, that is to say a short chain composed of four amino acids linked together by peptide bonds. In the form used in cosmetics, this sequence is modified by the addition of an acetyl group at one end, a chemical modification that helps improve its stability and its compatibility with cosmetic formulations. Small-sized peptides such as this one are of particular interest because they can interact with skin cells and take part in certain biological mechanisms of the skin.

Acetyl tetrapeptide-2 is often described as a biomimetic peptide, meaning that it partially reproduces the activity of certain molecules that are naturally present in the body. Its structure is inspired in particular by fragments of proteins involved in cellular communication and in maintaining the structure of skin tissues. Thanks to its small molecular size and water-soluble nature, this active ingredient can be incorporated into different types of cosmetic formulations, such as serums, creams or lotions.

Acetyl tetrapeptide-2 is mainly studied for its preventive role in skin ageing. Experimental work suggests that it may stimulate the synthesis of several proteins, notably collagen, fibrillin and elastin, which contribute to skin firmness and elasticity. Furthermore, acetyl tetrapeptide-2 may limit collagen degradation by interfering with certain enzymes responsible for its breakdown. These mechanisms would help to maintain the integrity of the extracellular matrix and to improve the anchoring between skin cells and their surrounding environment.

Beyond its potential effects on dermal structure, acetyl tetrapeptide-2 could also influence pigmentation. Experimental data indicate that it may modulate certain stages of melanogenesis, the process of melanin production. By inhibiting specific enzymatic reactions involved in this biological pathway, this peptide could help reduce the appearance of pigment spots and improve overall skin tone uniformity. Nonetheless, clinical evidence remains limited and these effects still need to be confirmed by further studies.

Acetyl tetrapeptide-2 is also attracting growing interest in the field of hair care. Research suggests that it could help maintain the hair growth cycle. In vitro, this peptide has shown an ability to reduce the expression of TNF-α, a pro-apoptotic factor involved in shortening the anagen phase, the active growth phase of the hair, and in triggering the catagen phase, the regression phase. By limiting this biological signal, acetyl tetrapeptide-2 may help to prolong the growth phase of the hair follicle and support hair regeneration. Some observations also indicate that it may stimulate the proliferation of interfollicular keratinocytes and promote the synthesis of structural hair proteins.

A clinical study specifically examined the effectiveness of a hair lotion containing creatine, acetyl tetrapeptide‑2 and B vitamins in women suffering from telogen effluvium, a form of hair loss that typically occurs a few months after a triggering event (severe stress, illness, childbirth, etc.). In this trial involving 100 women, participants were divided into a group using the lotion in combination with a mild shampoo and a control group using the shampoo alone. Assessment of hair parameters showed that the anagen/telogen ratio, an indicator of the proportion of hairs in the growth phase, increased more rapidly in the group using the lotion. A significant reduction in the density of hairs in the telogen phase and a decrease in the number of shed hairs were also observed at certain time points in the study, suggesting a faster recovery from hair loss.

Lastly, as with other cosmetic peptides, the effectiveness of acetyl tetrapeptide-2 depends in part on the formulation in which it is incorporated. The rheological properties of the products influence the release and penetration of this type of molecule into the skin or scalp. For example, some studies indicate that hydrogels, due to their lower viscosity, may allow a faster diffusion of tetrapeptides. However, this still needs to be confirmed.

Despite these encouraging results, clinical data are still relatively limited and further research is required to confirm the cosmetic benefits of acetyl tetrapeptide-2.

Like many peptides used in cosmetics, acetyl tetrapeptide-2 appears to have a good safety profile.

To date, the scientific literature has not reported any adverse effects or specific toxicity associated with this ingredient. However, it should be noted that toxicological data specific to acetyl tetrapeptide-2 remain limited, and that the available studies focus mainly on its biological properties rather than its long-term safety. As with any cosmetic ingredient, tolerance may vary from one individual to another. It is therefore recommended to patch test the product on a small area of skin, for example in the crook of the elbow, before first use on a larger area. This precaution makes it possible to confirm the absence of a skin reaction, particularly in individuals with sensitive skin.

• ALMEIDA I. F. & al. Trending anti-aging peptides. Cosmetics (2020).

• MENGEAUD V. & al. Assessment of the effects of a hair lotion in women with acute telogen effluvium: A randomized controlled study. Journal of the American Academy of Dermatology and Venereology (2021).

• ALMEIDA I. F. & al. Usage of synthetic peptides in cosmetics for sensitive skin. Pharmaceuticals (2021).