Expression lines can be one of the most common concerns: they form when you smile, frown, or raise your eyebrows. Understanding why they appear helps you choose the right way to address them in your daily routine.
Here are the keys to understanding them and learning how to improve the appearance of expression lines.
What are expression lines?
Expression lines, also known as dynamic wrinkles, are the lines that appear when you make facial expressions. Every time you contract your facial muscles, the skin folds. When the skin is young and elastic, it returns to its original shape; over time, however, and with repeated facial movements, that fold begins to become permanently etched into the skin.
They are usually found on the forehead, between the eyebrows, and in the crow’s feet area. At first, they are dynamic—that is, they are only visible when you make facial expressions. Over time, some may become deeper and remain visible even when the face is at rest, leading to permanent wrinkles.
Why do expression lines appear?
The root cause lies in the repeated movement of facial muscles, but it is not the only factor. Over the years, the skin produces less collagen and elastin, loses its ability to return to its original state after each facial expression, and the lines become more deeply etched.
In addition, there are factors that can accelerate the process, such as sun exposure, dehydration, smoking, stress, or lack of rest. Genetics and each person’s own expressiveness can also play a role.
How can you improve expression lines?
Although expression lines are caused by repeated facial movements, their appearance also depends on the skin’s elasticity, firmness, and hydration levels. That’s why skincare can help address them on several fronts: preventing expression lines, smoothing out existing wrinkles, and improving the skin’s quality and elasticity.
To do this, there are key active ingredients that work together and that you can incorporate into your skincare routine:
- Anti-wrinkle peptides: help improve the appearance of existing expression lines.
- Firming and regenerating active ingredients: help improve the skin’s firmness and elasticity.
- Moisturizing active ingredients: help keep the skin supple and improve the appearance of expression lines associated with dehydration.
The combination of these active ingredients allows for a more comprehensive approach to expression lines, both in terms of prevention and improving their appearance.
BTSES MIMETIC: Three-Tiered Anti-Wrinkle Action
As we’ve already mentioned, expression lines aren’t caused by a single factor. That’s why BTSES MIMETIC offers a comprehensive approach that combines three mechanisms of action in its B-TOX SYSTEM+ formula.
Its formula combines a botulinum polypeptide, which helps minimize the signs associated with repetitive skin tension; an anti-wrinkle peptide, which helps smooth out existing expression lines; and EGF (epidermal growth factor), which promotes skin regeneration and helps improve firmness and elasticity.
This combination of active ingredients is complemented by an immediate-tightening complex, niacinamide, adenosine, hyaluronic acid, and Centella asiatica, to improve both hydration and the skin’s texture and overall appearance.
The result is a serum that addresses various aspects related to expression lines: from helping to minimize the signs associated with repetitive movements to improving the appearance of already visible expression lines. In addition, the moisturizing active ingredients help keep the skin hydrated and achieve a smoother, more even complexion.
When do you start to see results?
Some effects, such as the sensation of firmer, smoother skin, may be noticeable within a few days. With BTSES MIMETIC, 72% of users report feeling firmer skin after just one week of use¹.
Improvements in wrinkles take longer. In a clinical study, BTSES MIMETIC achieved up to a 42% reduction in wrinkles after 56 days, and 77% of users reported that their expression lines had diminished on the forehead, between the eyebrows, and around the eyes².
¹Subjective efficacy study of BTSES MIMETIC serum conducted on 22 subjects over 56 days of use with two applications daily. Data on file, Sesderma, 2026.
²Clinical efficacy study of BTSES MIMETIC Serum conducted on 22 volunteers over 56 days of use with two applications daily. Data on file, Sesderma, 2026.
Frequently asked questions about expression lines
Can expression lines be eliminated with cosmetic products?
Cosmetics can visibly reduce their depth and help prevent the appearance of new wrinkles or expression lines.
Is botulinum polypeptide the same as botulinum toxin?
No. Botulinum polypeptide is an active ingredient that is part of the light chain of botulinum toxin. It acts on the skin to help gradually smooth and prevent expression lines.
What is the difference between a conventional anti-wrinkle serum and one specifically formulated for expression lines?
A conventional anti-wrinkle serum typically focuses on improving general signs of aging, such as loss of firmness, elasticity, or hydration. In contrast, a serum specifically formulated for expression lines incorporates active ingredients that help improve the appearance of expression lines formed by repeated facial movements, such as those on the forehead, between the eyebrows, and crow’s feet.
This is the case with BTSES MIMETIC, which combines botulinum polypeptide, an anti-wrinkle peptide, and EGF growth factor to help prevent and correct visible lines while improving skin quality.
At what age should you start?
There is no specific age to start addressing expression lines, as their appearance depends on multiple factors. The important thing is to maintain good hydration and sun protection from an early age and, when the first lines begin to appear, incorporate specific active ingredients that help improve their appearance and prevent their development.
Expression lines are part of what makes us unique. Skincare isn’t about erasing every line, but about maintaining the skin’s quality, elasticity, and radiance at every stage. Combining active ingredients that target visible expression lines with ingredients that improve skin quality is a way to take a comprehensive approach to skincare.
