The frown line, located between the eyebrows, is one of the first to appear on the face, often as early as the thirties. The result of repeated contraction of the glabellar muscles — mainly the corrugator supercilii and the procerus — it gives a worried, sometimes severe or tired look. At first, it is only visible when the face moves, during expressions such as concentration or annoyance. But over time, it can deepen further and become visible even at rest, forming a more or less pronounced permanent fold.
The treatment of this wrinkle is based on two complementary approaches : muscle relaxation with botulinum toxin (Botox), and filling the hollow with hyaluronic acid. The question of combining them in the same therapeutic strategy is now perfectly legitimate and is the subject of numerous clinical validations.
It is not only possible, but often recommended, to combine these two techniques — provided a logical sequence and a precise indication are respected. This text offers a detailed analysis of this combined approach in the treatment of the frown line.
The frown line is initially an expression line, called dynamic. It forms due to repeated contractions of the muscles located between the eyebrows, which crease the skin vertically. In the first years, an injection of botulinum toxin often suffices to relax these muscles and make the wrinkle disappear.
But over time, the repetition of these movements ends up damaging the skin : collagen fibers break down, elasticity decreases, and a rupture forms in the dermis. When the wrinkle remains visible even after a properly performed injection, it means that the skin has been altered more deeply. At this stage, muscle relaxation alone is no longer sufficient.
At this stage, hyaluronic acid becomes essential : it allows filling the wrinkle, restoring lost volume, and smoothing the skin surface. In other words, Botox acts on the muscular origin of the problem, while hyaluronic acid repairs its effects on the skin. Their combined action is therefore not redundant, but complementary, each acting at a different level to offer a more natural and balanced result.
In the vast majority of cases, the combination must follow a precise therapeutic order. Botox is injected first, into the glabellar muscles, with a dose adapted to the patient’s muscle strength. Its effect begins to appear within 3 to 5 days, with a complete result after 2 weeks.
This interval is essential to assess the real effect of Botox alone. Indeed, it happens that muscle relaxation is sufficient to significantly soften the wrinkle, making filling unnecessary. In other cases, if a persistent break remains, hyaluronic acid is injected two weeks after the Botox injection, into the skin depression to fill it.
This two-step approach helps avoid overcorrection, limits the injected volumes, and ensures a natural and harmonious result.
The glabella is a high-risk anatomical area due to its complex vascularization. Several arteries (notably the supratrochlear and supraorbital branches) run near the frown line, making any deep injection potentially dangerous.
That is why the hyaluronic acid used in this area is specifically chosen for its low viscosity and good tissue integration. The injection is performed :
The injected volume always remains modest : between 0.05 ml and 0.3 ml on average. The goal is not to plump, but to perfectly fill the wrinkle.
The combination of the two techniques allows achieving a result greater than the sum of the two procedures taken separately. Indeed :
Furthermore, a properly conducted combination often allows spacing out the sessions : results generally last between 8 and 10 months, compared to 4 to 6 months for Botox alone. This strategy is particularly suitable for more mature patients, or when the frown line is already well marked.
The Botox–hyaluronic acid combination, although very effective, is neither routine nor harmless. It requires several precautions :
In case of doubt about local vascularization, an experienced doctor will refrain from filling and propose a conservative approach, as the main risk remains skin ischemia or, more rarely, a vascular embolism.
In young patients, whose wrinkle is purely dynamic, Botox alone is generally sufficient. In more mature patients, or when the skin already shows a deep break, it is common to propose a complementary hyaluronic acid filling after the Botox injection.
The decision to combine the two techniques always relies on a personalized analysis of the face, taking into account not only the morphology and skin quality, but also the patient’s expectations, injection tolerance, and medical history. Each treatment must be tailor-made.
While the combination of Botox and hyaluronic acid remains the most comprehensive solution for treating the frown line, other options can be proposed, either as a complement or as an alternative depending on the case. Among them are Skinboosters or ablative laser.
These techniques help improve skin quality, stimulate collagen production, and slow the progression of wrinkles. However, they do not replace the action of Botox, which acts on the responsible muscles, nor that of hyaluronic acid, which fills already marked wrinkles. Their role is rather preventive or for maintenance, with gradual effects that are less dramatic than immediate correction.
From a technical point of view, it is possible to inject Botox and hyaluronic acid during the same session, provided different injection planes are respected. However, this practice is generally not recommended, especially for the glabella.
The reason is simple : the effect of Botox only appears several days after the injection. Therefore, it is not possible to know immediately which part of the wrinkle will disappear with muscle relaxation. Injecting a filler too early risks overcorrection, asymmetry, or increasing the risk of vascular complications or diffusion of the botulinum toxin.
Spacing the two treatments, leaving about 3 weeks in between, is therefore not a constraint but a guarantee of safety and precision. It allows assessing the real effect of Botox, then intervening only where filling is still necessary.
Several studies published in dermatology and aesthetic medicine journals validate the superiority of the combined protocol compared to using Botox or hyaluronic acid alone. A 2020 publication in the Journal of Cosmetic Dermatology shows that in patients with moderate to severe glabellar wrinkles, the combination of the two products results in a faster, more significant, and longer-lasting improvement, with higher patient satisfaction.
A meta-analysis published in the Aesthetic Surgery Journal shows that patients treated with a protocol combining Botox and hyaluronic acid require fewer filling sessions in the long term. This reduction is explained by the muscle relaxation induced by botulinum toxin, which decreases mechanical stress on the injected hyaluronic acid, improves its anatomical stability, and slows its resorption.
Furthermore, studies indicate that the complication rate does not increase when the combination is performed following best practices, both in terms of timing and technique. These data therefore support experienced physicians in considering this approach as a therapeutic reference in the management of deep glabellar wrinkles.
Article written by Dr Romano Valeria
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