The frown line — this vertical or double furrow located between the eyebrows — is among the most common aesthetic concerns of the upper third of the face. It appears as a result of repeated contractions of the corrugator and procerus muscles, activated daily by expressions of concentration, annoyance, or stress. Over time, these micro-contractions gradually imprint their mark on the skin, eventually creating a persistent crease, visible even at rest.
To address this sometimes early sign of aging, injections of type A botulinum toxin (more commonly known as Botox®) have established themselves as the first-line treatment. Their growing popularity is due to a dual promise : rapid effectiveness, observable within the first few days, and an excellent level of safety when administered by an experienced physician.
One essential question remains : what can be realistically expected from this treatment ? What do clinical studies show, and what do patients report from their experience ? This text aims to answer these questions by combining scientific literature, medical expertise, and practical observation.
The frown line does not result from skin laxity due to aging, but from repeated muscular hyperactivity. It is an expression line, also called a dynamic wrinkle. It appears as a result of regular contractions of the glabella — the area located between the eyebrows — driven by powerful muscles that work to draw the eyebrows toward the center and downward. These movements often reflect intense emotions : concentration, annoyance, stress.
Over time, the repetition of these contractions imprints its mark on the dermis, eventually forming a lasting crease, visible even at rest. This is why creams or massages, whose action remains superficial, have only a limited effect : the cause lies in depth, within the muscular dynamics.
Botulinum toxin addresses this mechanism precisely. By temporarily inhibiting the release of acetylcholine at the neuromuscular junctions, it blocks the action of the responsible muscles. This targeted relaxation allows the skin to gradually smooth out, providing a noticeable reduction of the frown line while preserving the naturalness of expression.
The effectiveness of Botox in the frown line area is considered very high when injected precisely. Patients report visible improvement within 3 to 7 days after the injection, with maximal effect reached around two weeks.
Clinically, the effects include :
In the majority of cases, the dynamic frown line disappears completely, and the static line partially, or even fully, fades if it is still mild. Results are generally reproducible and can be maintained with maintenance sessions spaced 4 to 6 months apart.
The effectiveness of botulinum toxin for the treatment of the frown line has been demonstrated by numerous randomized and controlled clinical studies. One of the most frequently cited, published in the Journal of the American Academy of Dermatology, shows that more than 85 % of patients who received a Botox injection in the glabella experienced a significant improvement in wrinkle severity, with a high level of satisfaction even six months after treatment.
Multicenter trials conducted as part of the European and U.S. marketing authorizations have also validated the use of Botox for this specific indication, based on strict criteria : clinical reduction of dynamic wrinkles, short- and medium-term safety, and reproducibility of results.
The tools used in these studies (such as the Glabellar Line Severity Scale, a validated visual scale) confirm a significant reduction in wrinkles within the first two weeks after injection, with a measurable effect in 90 % of cases.
The action of Botox is temporary but long-lasting. On average, its effects last from 4 to 6 months, depending on initial muscle strength, the frequency of facial expressions, and the individual characteristics of each patient. Over the course of several sessions, a lasting improvement in the frown line is often observed, even after the pharmacological effect fades, thanks to the progressive reduction of muscle activity in the treated area.
In some patients, particularly younger ones or those with moderately active muscles, a single injection is enough to smooth the glabella for several months without the need for a touch-up. Conversely, more expressive patients or those with deeper wrinkles benefit from a follow-up session at 15 days, followed by maintenance treatments every six months.
It is important to remember that Botox does not act permanently : its effectiveness is not curative. However, when used regularly, it helps slow the progression of dynamic wrinkles and, in some cases, prevent their formation.
When the frown line becomes visible at rest, it no longer reflects just an expression but indicates a structural change in the dermis. In this case, botulinum toxin remains the treatment of choice, as it directly targets the underlying mechanism : repeated muscle contraction. It therefore helps stabilize the wrinkle and relax the affected area.
When the skin crease is more pronounced, a filler with hyaluronic acid can be combined. The combined action of both treatments optimizes results : botulinum toxin addresses the functional cause, while hyaluronic acid corrects the structural consequence.
Thus, even when it appears permanently established, the treatment of the frown line should still begin with botulinum toxin. Its targeted, reversible, and well-tolerated action makes it a key tool in the management of expression lines.
One of the main advantages of Botox in the glabellar area (between the eyebrows) is that it provides visible results without freezing the face. When properly dosed and precisely injected, it relaxes the area without blocking natural expressions. The eyes remain lively, the eyebrows retain their mobility, and the expressiveness of the face is preserved.
Studies show that side effects are very rare, especially when the treatment is performed by an experienced physician. Overly frozen or artificial results are exceptional in this context. The effectiveness of Botox does not depend on using a large amount of product, but rather on a precise understanding of facial anatomy and respect for muscular dynamics.
Article written by Dr Romano Valeria
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