In 1787, Élisabeth Louise Vigée Le Brun, painter to Marie Antoinette, showed a self-portrait at the Paris Salon in which she smiles with her lips parted and her teeth visible. Critics objected. An open smile broke the conventions of polite portraiture.

Patients bring me a modern version of that objection. They hold a hand over the mouth when they laugh, or they rehearse a closed-lip smile for photographs. For some, the reason is the gum that shows above the upper teeth, what clinicians call excessive gingival display and patients call a gummy smile.

My argument is that botulinum toxin (Botox) is an effective first step for a gummy smile driven by a hyperactive upper lip, and that it should be offered honestly as a first step: the effect fades within months, the studies disagree with one another, and the options that last longer have been studied less rigorously. Five papers carry the case: two meta-analyses, two systematic reviews, and a retrospective surgical series in Plastic and Reconstructive Surgery.

How does Botox treat a gummy smile? The muscles it targets

Botox treats a gummy smile by weakening the muscles that lift the upper lip, so the lip rises less when you smile. In a 2024 systematic review of 13 prospective, controlled clinical trials, the main targets were the levator labii superioris alaeque nasi, the levator labii superioris and the zygomaticus minor, and the dose was set according to how much gum showed (Wang et al., 2024). A 2023 meta-analysis reported doses of 1.25 to 7.5 units per side, aimed mainly at the first two of those muscles (Rojo-Sanchis et al., 2023).

This is where patient selection matters. Wang and colleagues conclude that the toxin works for gummy smiles triggered by muscle hyperactivity (Wang et al., 2024), and a 2026 review describes excessive gingival display as frequently associated with upper lip hypermobility (Siano et al., 2026). Neither statement says that every gummy smile is a muscle problem.

How much does Botox reduce gum display? The pooled numbers

Pooled data report a reduction of roughly 3 mm in gum display two weeks after injection. The 2023 meta-analysis searched the literature through June 2021 and included 15 studies in its qualitative analysis and 11 in its quantitative analysis. Baseline gingival exposure ranged from 3.5 to 7.2 mm. At two weeks the pooled reduction was 3.22 mm (95% CI, −4.43 to −2.01; 9 studies, 213 patients), and at three months it was 2.70 mm (95% CI, −4.52 to −0.88; 5 studies, 182 patients) (Rojo-Sanchis et al., 2023). Units of toxin did not significantly change the size of the reduction (Rojo-Sanchis et al., 2023).

A second meta-analysis of 17 articles found a mean reduction of 3.42 mm at two weeks (95% CI, −4.50 to −2.34) (Zengiski et al., 2022). The 2024 systematic review reported baseline exposure of 3.5 to 6.8 mm, a maximum effect at 2 to 4 weeks, and, in most studies, gum exposure reduced to 3 mm or less (Wang et al., 2024).

Read those numbers with the baseline in mind. A 3 mm reduction is large when the starting point is 3.5 to 7 mm, and modest when it is not.

Then read the heterogeneity, the degree to which studies disagree. I² was 95.3% at two weeks and 97.9% at three months in the first meta-analysis (Rojo-Sanchis et al., 2023), and 97% in the second (Zengiski et al., 2022). Twelve of the 13 studies assessed for risk of bias were rated moderate risk, and the authors noted that studies lacked standardized protocols for photography, measurement methods and anatomical reference points (Rojo-Sanchis et al., 2023).

How long does gummy smile Botox last?

The effect peaks within weeks and fades over months. The 2024 systematic review reported effects lasting up to 12 to 24 weeks (Wang et al., 2024). The second meta-analysis found the toxin effective for up to 12 weeks, with values returning close to baseline within 24 weeks, and described it as especially suited to gummy smiles of up to 4 mm (Zengiski et al., 2022). In its meta-regression, the timing of application explained 29.58% of the variance between studies, and the effect declined progressively from week two onward (Zengiski et al., 2022).

The 2023 meta-analysis points the other way. It found no significant difference between the two-week and three-month results, though its follow-up beyond 12 weeks was limited (Rojo-Sanchis et al., 2023). The two reviews pool different studies and both carry very high heterogeneity, so I would not treat either as the last word. What they share is that nothing in them suggests the effect is permanent.

What are the side effects of botulinum toxin for a gummy smile?

Reported complications are mild and uncommon. The 2023 meta-analysis listed injection-site pain, edema, hematoma, mild erythema and asymmetric smile (Rojo-Sanchis et al., 2023). The 2024 review described high safety, minimal side effects and high patient satisfaction (Wang et al., 2024), and the 2026 review documented no serious adverse effects across the treatments it compared (Siano et al., 2026).

An asymmetric smile deserves a second look, because the smile is exactly what is being edited. It is a reason to ask who will inject and how the result will be checked, not a reason to dismiss the option.

What are the alternatives to Botox for a gummy smile? Lip repositioning and fat transplantation

Surgical options last longer than Botox, but they are also studied in less uniform ways. A 2026 systematic review of 17 studies compared botulinum toxin, lip repositioning surgery and combinations of the two. Its conclusion was that the toxin provided rapid but temporary improvement, that modified lip repositioning showed greater stability over time, and that combined approaches appeared to give the most consistent long-term results (Siano et al., 2026).

A third route is micro-autologous fat transplantation (MAFT), in which the patient's own purified fat is injected into the nasolabial groove, the area around the upper lip and the upper lip itself. A 2026 retrospective study in Plastic and Reconstructive Surgery reviewed 52 patients (mean age 43.4 years; 92.3% female) treated between 2014 and 2023, with a mean follow-up of 56.4 months (Li et al., 2026). Gingival exposure fell from a mean of 3.31 mm to −0.82 mm, a mean reduction of 4.13 mm (p < 0.00001), and satisfaction on a 5-point scale rose from 1.40 to 4.90 (Li et al., 2026). Mean injected volume was 16.1 mL, volume did not correlate with outcome, two patients (4%) needed minor touch-ups, and no major complications occurred (Li et al., 2026).

I read the abstract of this paper only, and its text is not freely available to me. The abstract does not explain how a negative gingival exposure value was defined, which is worth knowing before anyone compares it with the Botox numbers.

The strongest objection

Some will say that a surgical series reporting a 4.13 mm reduction at nearly five years, against a toxin that fades in months, settles the question in favor of fat transplantation. That is partly true. On durability, the numbers favor the longer-lasting option (Li et al., 2026; Siano et al., 2026).

But durable and well studied are different things. The MAFT report is retrospective, has 52 patients and no comparison group, and measured satisfaction on a simple 5-point scale (Li et al., 2026). The toxin literature is larger and includes controlled trials, but it is highly heterogeneous, and 12 of the 13 studies assessed for risk of bias in the 2023 meta-analysis were rated moderate risk (Rojo-Sanchis et al., 2023). The 2026 review itself calls for standardized protocols and longer studies (Siano et al., 2026).

What should you ask before treating a gummy smile?

Start with the cause. Ask whether the gum show comes mainly from a lip that rises too far, since that is the situation in which the toxin evidence applies (Siano et al., 2026; Wang et al., 2024). Ask how much gum shows now, in millimeters, because the second meta-analysis suggests the toxin suits gummy smiles of up to 4 mm best (Zengiski et al., 2022).

Ask what the plan is when the effect fades. The reviewed studies describe effects lasting up to 12 to 24 weeks (Wang et al., 2024), so repeating the treatment or moving to a longer option is part of the conversation from day one. Ask how the result will be measured, with standardized photographs at set time points, since the literature itself lacks that (Rojo-Sanchis et al., 2023). Ask about smile asymmetry and what happens if it occurs, and ask what the alternatives are, including lip repositioning and fat transplantation, and why they are or are not suited to you (Li et al., 2026; Siano et al., 2026).

The Clinical Bottom Line

Botox is a sound first step for a gummy smile caused by an overactive upper lip, offered with the understanding that it is temporary. Pooled data report a reduction of roughly 3 mm at two weeks (Rojo-Sanchis et al., 2023; Zengiski et al., 2022), reported complications are mild (Rojo-Sanchis et al., 2023; Wang et al., 2024), and effects are described as lasting up to 12 to 24 weeks (Wang et al., 2024).

The caution is about what comes after. The longer-lasting options, lip repositioning and fat transplantation, look more durable but rest on smaller and less controlled evidence (Li et al., 2026; Siano et al., 2026). We still lack standardized measurement, head-to-head trials and long follow-up.

Vigée Le Brun painted the open smile anyway. A good consultation lets the patient decide how much of it to show, and for how long.

For clinical assessments and consultation in Seoul: itsdrbock.com

References

Li, W.-T., Chen, W.-H., Lin, Y.-N., Chou, C.-K., Lin, S.-D., & Lin, T.-M. (2026). Micro-autologous fat transplantation (MAFT) as a novel therapeutic approach for gummy smiles: Long-term efficacy and mechanistic insights. Plastic and Reconstructive Surgery. Advance online publication. https://doi.org/10.1097/PRS.0000000000012884

Rojo-Sanchis, C., Montiel-Company, J. M., Tarazona-Álvarez, B., Haas-Junior, O. L., Peiró-Guijarro, M. A., Paredes-Gallardo, V., & Guijarro-Martínez, R. (2023). Non-surgical management of the gingival smile with botulinum toxin A: A systematic review and meta-analysis. Journal of Clinical Medicine, 12(4), Article 1433. https://doi.org/10.3390/jcm12041433

Siano, M., Costa, R., Relvas, M., Vinhas, A. S., Reis, C., & Cabral, C. (2026). Gummy smile: Comparison between botulinum toxin, lip repositioning surgery and combined techniques in cases of lip hypermobility: A systematic review. Oral, 6(2), Article 49. https://doi.org/10.3390/oral6020049

Wang, X., Zou, Y., Yuan, M., Huang, H., Han, X., & Gong, X. (2024). Dose and injection site of botulinum toxin type A for gummy smile management: A systematic review and bibliometric analysis. Toxicon, 249, Article 108058. https://doi.org/10.1016/j.toxicon.2024.108058

Zengiski, A. C. S., Basso, I. B., Cavalcante-Leão, B. L., Stechman-Neto, J., Santos, R. S., Guariza-Filho, O., Zeigelboim, B. S., Taveira, K. V. M., & de Araujo, C. M. (2022). Effect and longevity of botulinum toxin in the treatment of gummy smile: A meta-analysis and meta-regression. Clinical Oral Investigations, 26(1), 109–117. https://doi.org/10.1007/s00784-021-04223-w