Introduction
When you first got Botox and looked in the mirror the following month, did you ever think, "Wait, is the effect already fading?"
In fact, that feeling is not just your imagination. Depending on the area,65 daysresearch papers show data indicating that the effect is reduced by half.
So which areas last longer? Can increasing the dose solve this? Is there a difference between men and women?
What this article will clarify:
- The medical mechanism of how Botox effects wear off and the neural regeneration process
- Precise duration data for each facial area—between the eyebrows, around the eyes, forehead, around the mouth
- Differences in duration based on injection volume (units) and Botox type (product brand)
- Duration of effects from injections into the masseter (jaw muscle enlargement) and functional risks from repeated injections
- Differences in Botox efficacy between men and women
Rather than relying on personal sensation or clinic marketing claims, we will provide a thorough explanation by treatment area using only rigorous clinical trial data from research papers. By the time you finish reading, you should have a clear understanding of "what to choose and how to proceed with your next injection."
1. Botox (BontA) basics: Why does the effect wear off?
First, what you need to know is that Botox does not last forever—but that is not a bug; it is a feature.
Understanding the mechanism of how effects wear off will show you that it is actually "proof of safety." In aesthetic medicine, botulinum toxin type A (BontA) injections for dynamic wrinkles (expression lines) are the most common treatment. According to statistics from the American Society of Plastic Surgeons, in 2016 alone,4,597,886 injectionswere performed (ASAPS 2016). Additionally, the average cost per wrinkle treatment session is reported to be$385 USDand this procedure is performed on large numbers of people worldwide (ASAPS 2017).
The reason BontA has become so widely adopted is that compared to surgical procedures, the cost is low, there is no downtime, and most importantly, "the effect is temporary" (Glogau 2012). Because the effect does not last forever, there is peace of mind knowing that if you are dissatisfied with the result, it will eventually revert to normal.
So why is the effect temporary?
Once injected into the muscle, botulinum toxin diffuses and binds at the nerve terminal, blocking the release of the neurotransmitter "acetylcholine" from the synaptic nerve. This prevents the muscle from moving, so the skin does not wrinkle. Complete muscle paralysis occursapproximately 5–15 daysafter injection (Berry 2012).
However—the human body is sophisticated, and here is where things really begin.
To compensate for the non-functioning nerve terminal, a process called "sprouting" triggers the regeneration of new nerve terminals. This sprouting processcontinues for approximately 120 daysand forms new nerve terminals at the neuromuscular junction, restoring muscle activity (Berry 2012). Therefore, the clinical duration of treatment effect is reported to fall within an average range of3–6 months (approximately 90–180 days)(Glogau 2012; Berry 2012).
In other words, the moment you feel the effect "wearing off" is evidence that your body is functioning normally. Now let's look at the duration by treatment area in numerical terms.
2. [By Treatment Area] Duration of Botox effects according to research data: Between the eyebrows
Average: 99.7 days.This is the number produced by a large-scale systematic review for the duration of Botox treatment for glabellar lines (frown lines between the eyebrows).
Glabellar lines (frown lines between the eyebrows) are the most frequently analyzed area in Botox treatment research, with abundant data available. This figure, derived from randomized controlled trials (RCTs), varies significantly depending on injection volume, product, and ethnicity.
For example, look at Japanese patient data. In a study of Japanese patients, the average effect duration for OnabotulinumtoxinA (Botox by Allergan) 20 units (U) was9.4 weeks (approximately 65 days), and for 10U was7.9 weeks (approximately 55 days)(Harii 2008). Even with the standard 20U dose, the effect begins to diminish after roughly two-and-a-half months.
On the other hand, research centered on North America tells a different story. According to a dose-comparison study using OnabotulinumtoxinA, the duration for glabellar lines is as follows (Carruthers 2005a; Carruthers 2005b):
- 20U group:17.6 weeks (approximately 123 days)
- 40U group:21.7 weeks (approximately 151 days)
- 60U group:22.8 weeks (approximately 159 days)
- 80U group:24.2 weeks (approximately 169 days)
The numbers speak volumes. The more you increase the dose, the longer the duration extends.
Furthermore, in a study by Solish et al., the duration of OnabotulinumtoxinA 30U for glabellar and forehead wrinkles was16 weeks (113.0 days)by physician evaluation and16.5 weeks (115.5 days)by patient evaluation; for 40U, physician evaluation showed16.9 weeks (118.5 days)and patient evaluation showed17.8 weeks (125 days)(Solish 2016).
"Increasing the dose makes it last longer"—this is true for the glabellar area. However, the risks of increasing the dose will be explained in detail in later sections.
3. [By Treatment Area] Duration of Botox effects according to research data: Crow's feet
How do crow's feet (wrinkles around the eyes) compare to the glabellar area? The answer might surprise you.
The area around the eyes has thin skin and muscle movements easily translate into wrinkles. Intuitively, you might think "the effect appears less obviously and wears off quickly." However—
In an RCT of Japanese patients, when OnabotulinumtoxinA totaling 12U was injected on both sides of the crow's feet area, the duration was85 days, and when 24U was injected, it was95 days(Harii 2017). Similar to the glabellar area, the tendency for higher doses to last longer is confirmed.
But here comes the surprising data.
In another study, when OnabotulinumtoxinA 24U was injected into the crow's feet, the duration according to both physician and patient assessment was reported asapproximately 150–157 days(Wu 2019). Furthermore, a multi-center collaborative study reported that the duration (median) was16.8 weeks (118 days)by physician assessment and16.5 weeks (116 days)by patient assessment, with some conditions reaching a maximum of20.5 weeks (144 days)(Carruthers 2014).
The crow's feet area may last as long as or even longer than the glabellar area. The misconception that "crow's feet wear off quickly" is contradicted by the data.
4. [By Treatment Area] Duration of Botox effects according to research data: Fine lines around the mouth and the surprising synergistic effect with hyaluronic acid
Fine vertical lines around the mouth (perioral lines)—this is the area with the shortest duration. And there is a method that dramatically changes this.
The area around the mouth is frequently moved during eating and talking. In one study, when OnabotulinumtoxinA 9U was injected, the average duration was9.9 weeks (69.3±11.0 days)(Carruthers 2010). This is clearly shorter than the glabellar or crow's feet areas.
Here I would like to pose one question—if you are paying the same amount, wouldn't you want it to last as long as possible?
In a group where the same 9U of Botox was combined with hyaluronic acid (24-mg/mL cohesive gel), the average duration was extended to15.2 weeks (106.6±10.6 days)(Carruthers 2010).
The comparison in numbers is striking:
- Botox alone:approximately 70 days
- Botox + hyaluronic acid:approximately 107 days
With the same amount of Botox, simply adding hyaluronic acid extends the duration toapproximately 1.5 times**the original. For areas like the mouth that are moved frequently, combining with a filler is the most important key to controlling the effect duration.
5. Does the type (formulation) of Botox change the duration?
Does "which brand you choose" change the duration? To answer directly, conventional formulations show little difference—but next-generation options are in a different league.
Currently, multiple botulinum toxin type A (BontA) products exist in the aesthetic medicine market. The major ones approved by the FDA and EMA include Botox (OnabotulinumtoxinA), Dysport (AbobotulinumtoxinA), Xeomin (IncobotulinumtoxinA), and the newer DaxibotulinumtoxinA. All are type A toxins, but differ in bacterial strain and biological characteristics (potency equivalence, diffusion in the dermis, etc.) (Glogau 2012).
In a study where AbobotulinumtoxinA (Dysport) 50U was injected between the eyebrows, the median duration was reported as12 weeks (85 days)(Brandt 2009) to15.3 weeks (107 days)(Kane 2009), or117 days(Monheit 2019).
In research directly comparing three formulations, among women (Rappl 2013):
- IncobotulinumtoxinA:20.8 weeks (146.12 days)
- OnabotulinumtoxinA:20 weeks (140.65 days)
- AbobotulinumtoxinA:139.69 days
The differences are only a few days. Among the conventional three formulations, there are no dramatic differences in duration.
However—next-generation options are emerging.
In studies using DaxibotulinumtoxinA, which extends the effect through peptide technology, the effect duration for 60U was23.2 weeks (approximately 162 days), showing a dramatic difference compared to placebo's 0.4 weeks (Carruthers 2017). Furthermore, in a large-scale pooled data analysis of 40U, at the24-week (approximately 168 days)mark, a significantly higher responder rate compared to placebo was maintained (Bertucci 2020).
For patients who want "the longest-lasting effect possible," choice of formulation will become an increasingly important consideration going forward.
6. If you increase the injection dose (units), will it last longer?
Answer: To a certain extent, yes. But there is a limit.
Many patients wonder: "Will increasing the number of units make the effect last longer?" Based on the research data, a moderate dose increase definitely contributes to prolonging the duration.
As shown in the previously mentioned study by Carruthers et al. (Carruthers 2005a; Carruthers 2005b), increasing the OnabotulinumtoxinA dose for glabellar lines results in:
- 20U → 17.6 weeks
- 40U → 21.7 weeks
- 60U → 22.8 weeks
- 80U → 24.2 weeks
For crow's feet as well, what was85 daysachieved with 12U was extended to95 dayswhen increased to 24U (Harii 2017).
However, the question of whether "the more you increase, the better"—the answer is no.
Excessive unit doses carry a significantly increased risk of adverse effects such asptosis(drooping eyelids) and "Spock brow," where the expression becomes completely frozen and unnatural. There is always a tradeoff between increasing the dose and safety. Careful assessment and balance adjustment by the physician, tailored to each patient's muscle strength and facial expression patterns, is essential.
7. Do men and women respond differently to Botox?
Even with the same amount injected,men's effects wear off approximately 3–4 weeks earlier than women's.This is the conclusion of research data.
Generally, men have more strongly developed and larger volume of facial muscles (expression muscles) than women. This anatomical fact directly affects the duration of the effect.
In research that actually measured the effect duration separately by gender (Rappl 2013), consistent results appeared across all formulations:
- IncobotulinumtoxinA: Women20.8 weeks (146.12 days) vs. Men17.3 weeks (121.14 days)
- OnabotulinumtoxinA: Women20 weeks (140.65 days) vs. Men16.6 weeks (116.61 days)
- AbobotulinumtoxinA: Women139.69 days vs. Men115.81 days
Regardless of formulation, men clearly tend to experience effects wearing off approximately 25 days earlier.
This means that for men to achieve effects and duration equivalent to women, they likely need higher unit doses than the standard injection volume. During clinic consultations, it is an important point to confirm whether dose adjustment is being made considering sex and muscle strength in order to make the effect last longer.
8. Effects and duration of treatment for the masseter (jaw enlargement): The beauty-function dilemma
Botox for the masseter carries fundamentally different risks compared to facial wrinkles. Continuing to inject without understanding this is dangerous.
Botox injections into the masseter muscle are frequently performed for lower face contouring (reducing jaw prominence/creating a slimmer face) and to alleviate bruxism (teeth grinding/clenching). However, injection into this powerful muscle responsible for chewing shows a completely different response than thin expression muscles.
In a recent randomized, triple-blind trial in which women complaining of masseter hypertrophy (MH) were injected with AbobotulinumtoxinA at a high dose of 75U on each side (total150U), the patient's subjective jaw prominence was significantly improved at1 monthpost-injection. While there was temporary reduction in chewing ability, the muscle thickness itself began to recover by3 months(Nobre 2024). Another study showed that following a single injection of 30U OnabotulinumtoxinA, bite force and muscle activity gradually returned to normal over3 months(De la Torre Canales 2020). Additionally, a4-yearlong-term follow-up study of Asian patients showed that with regular injections, an average of12%muscle volume reduction was confirmed (Shome 2019).
However, look at the adverse event data.
In a study of AbobotulinumtoxinA (standard dose 140.62–187.5U) injected into the masseter, patients experienced some form of adverse event in18.8%of cases (Ozdemir Cetinkaya 2024):
- Smile asymmetry:2.5%
- Paradoxical bulging:2.5%
- Injection site pain and headache:3.8%
Furthermore, in patients with strong muscles, a single injection was insufficient, and8.8%of patients required additional touch-up injections at 10 days post-injection (Ozdemir Cetinkaya 2024). It is important to know that in masseter treatment, approximately 1 in 10 cases do not resolve with a single injection.
9. What happens if you keep getting injections? (Benefits and drawbacks of repeated injection)
"Does repeated injection lead to tolerance and reduced effectiveness?" The answer is opposite depending on the treatment area.
Repeated injection for facial wrinkles: Benefits are significant
In patients who received multiple regular OnabotulinumtoxinA injections, the responder rate (proportion of people showing effect) at 30, 60, 90, and 120 days was significantly higher in the 3rd cycle (3rd injection) compared to the 1st cycle (1st injection) or 2nd cycle (2nd injection). The incidence of adverse events also decreases with repeated treatments:
- 1st cycle:21.2%
- 2nd cycle:4.7%
- 3rd cycle:2.0%
With wrinkle treatment, regular injections at appropriate intervals allow excessive muscle movement habits to disappear, enabling maintenance of high effects with fewer adverse effects.
However—when it comes to the masseter (jaw muscle), the results are completely opposite.
Repeated injection to the masseter: Serious risk
In the Nobre et al. study (Nobre 2024), in the group that received a Botox booster injection at3 months, the masseter thickness and muscle activity measured by electromyography (EMG) did not recover at all at6 monthspost-procedure. Animal experiments and human research strongly suggest this indicates incomplete neural reinnervation, fat infiltration into the muscle, and muscle fiber necrosis or fibrosis (muscle hardening), leading topermanent atrophy.
Repeated injections at short intervals that deprive the masseter—essential for eating—of function for prolonged periods, simply to achieve a slimmer face, requires decision-making with full understanding of these risks.
Summary of this article
- Due to the neural regeneration (sprouting) process, Botox effects do not last permanently and generally disappear afterapproximately 4–6 months (120–180 days)(Glogau 2012; Berry 2012).
- The duration of effect for glabellar lines averages approximately 14 weeks (99.7 days), but research shows that increasing the injection dose can extend it to as long as24 weeks (approximately 6 months)(Carruthers 2005a).
- Effects for crow's feet tend to last relatively long, and some research confirms duration ofapproximately 150 days or longer (approximately 5 months)(Wu 2019).
- For perioral lines, combining with hyaluronic acid (approximately 3.5 months) shows dramatically longer-lasting effects than Botox alone (approximately 2.5 months) (Carruthers 2010).
- Because men have stronger, more developed muscle, the Botox effect tends to wear offapproximately 3–4 weeks earliercompared to women. Dose adjustment is necessary for men (Rappl 2013).
- The next-generation Botox, DaxibotulinumtoxinA, demonstrates longer and higher sustained duration of approximately24 weeks (168 days)compared to conventional formulations (Bertucci 2020).
- For masseter treatment, while a single injection allows muscle strength to recover in approximately 3 months, repeated injections at short intervals carry serious functional risks including permanent muscle atrophy and reduced chewing function, so caution is necessary (Nobre 2024).
"What about my case?"
Book a free consultation
We promise no high-pressure sales. Please feel free to contact us.
References
- Liew S, Scamp T, de Maio M, et al. Efficacy and Safety of a Hyaluronic Acid Filler to Correct Aesthetically Detracting or Deficient Features of the Asian Nose: A Prospective, Open-Label, Long-Term Study. Aesthetic Surgery Journal. 2016 DOI
- Rho N, Youn C, Youn S, et al. A comparison of the safety, efficacy, and longevity of two different hyaluronic acid fillers in filler rhinoplasty: A multicenter study. Dermatologic Therapy. 2021 DOI
- Kang G, Hsiao Y, Huang J, et al. Aesthetic Durable Forehead Contouring in Asians With Fat Grafting and Botulinum Toxin. Annals of Plastic Surgery. 2019 DOI
- E., R.A., R.M.. Journal of Cosmetic Dermatology. 2015
- Bellamy J, Rohrich R. Superiority of the Septal Extension Graft over the Columellar Strut Graft in Primary Rhinoplasty: Improved Long-Term Tip Stability. Plastic & Reconstructive Surgery. 2023 DOI
About the author of this article
Hiromitsu NakamuraPhysician, Ginza Clinic
Zetith Beauty Clinic Ginza, Osaka, and Fukuoka Branches
With a track record of research presentations at domestic and international academic conferences, he is also involved in technical instruction and education across all Zetith Beauty Clinic locations. He specializes in precision aesthetic medicine based on anatomical foundations and pursues natural results tailored to each patient's bone structure and tissue characteristics.