If you have a gummy smile caused by a lip that lifts too far, botulinum toxin is the treatment with the most evidence behind it, and Juvederm is not.
A systematic review of 13 prospective controlled clinical trials found that toxin injected into the lip-elevator muscles reduced gum show from a baseline range of 3.5 to 6.8 mm down to 3 mm or less in most cases, with maximum improvement at 2 to 4 weeks and an effect lasting roughly 12 to 24 weeks. The muscles targeted are the levator labii superioris alaeque nasi, the levator labii superioris and the zygomaticus minor — the small muscles that pull the upper lip up and out when you smile.
That is not the same as saying the evidence is strong: An evidence-based review in 2022 concluded there was "limited evidence, not higher than level III" supporting toxin for gummy smile linked to overactive muscles around the mouth. And no botulinum toxin brand holds an FDA cosmetic indication for a gummy smile either. Botox Cosmetic's cosmetic indications are glabellar lines, lateral canthal lines, forehead lines and platysma bands. Toxin for a gummy smile is off-label too — it is simply better studied.
The filler evidence sits a step below that again. It is mostly cohort studies, case series and technique descriptions, which the papers themselves label Level of Evidence IV.
Excessive gum display is conventionally defined as more than 3 mm of gum visible above the upper front teeth when you smile. But that single measurement has several different causes, and they do not respond to the same treatment.
Lip hypermobility: The muscles lift the upper lip further than average. This is the muscular type, and it is the type toxin is aimed at.
Vertical maxillary excess: The upper jaw is long, so the teeth and gums sit lower relative to the lip. This is skeletal. Injecting anything into soft tissue does not change bone; the definitive treatment is orthognathic (jaw) surgery.
Altered passive eruption: The gum never fully receded off the teeth as they came in, so the teeth look short and the gum looks large. The dental treatment is crown lengthening.
A short upper lip: An anatomical proportion, not a muscle problem.
Combinations are common. A page, or a clinic, that treats "gummy smile" as one condition with one treatment is going to get it wrong for a large share of people. Working out which of these is driving your smile is the first appointment, not the injection.
Two quite different filler ideas get bundled together in clinic copy, and they are worth separating.
1. Lip filler in the upper lip: This is what most people mean. Adding hyaluronic acid to the upper lip increases the amount of red lip (vermilion) on show and can make the lip look fuller and slightly longer. It changes the proportion between lip and gum. What it does not do is reduce how far the muscle lifts the lip when you smile. In someone whose gum show is driven by muscle pull, the muscle keeps pulling.
The relevant approvals here are for lip augmentation, not for gum show: Juvederm Ultra XC has been approved for injection into the lips and perioral area for lip augmentation in adults over 21 since 30 September 2015, and Juvederm Volbella XC has been approved for the lips and perioral lines since 31 May 2016. Note that Juvederm Ultra Plus XC does not hold a US lip indication — its approved wording covers moderate to severe facial wrinkles and folds, such as nasolabial folds.
2. Filler higher up, as "myomodulation": Here hyaluronic acid is placed in the premaxillary or paranasal area — around and above the base of the nose — either to add physical resistance against the lifting muscles, or to support a flat, deficient area under the nose. The published work behind this is expert clinical experience and case series, labelled Level of Evidence IV by the authors themselves, not trial evidence.
Neither use is FDA-approved for a gummy smile: No US hyaluronic acid filler carries an indication that names gum show or upper lip elevation.
The best single filler study is a cohort of 50 patients using a hyaluronic acid infiltration technique, 0.1 mL per injection point. Mean reduction in gum show on smiling was 2.5 mm, stable from one week. Satisfaction was 82.1 percent, and every patient said they would recommend it. The authors declared no conflicts of interest.
The durability finding in the same study is the one to hold on to: 40 percent of the original gum show had come back by 6 months, and the effect was completely gone at 12 months: That was a cohort with no control arm, so improvement over time cannot be separated from the natural course, but it is the clearest published picture of how long this lasts.
There is exactly one published head-to-head of botulinum toxin against hyaluronic acid filler for gummy smile. It enrolled 14 patients in total — about seven per arm — with 90 days of follow-up, at a single centre, with no stated blinding or randomisation method and no brands or doses reported. It reported that toxin gave immediate improvement while filler gave more consistent and prolonged results with higher satisfaction. A 14-patient study is not enough to establish that filler beats toxin here, and it should not be read that way. It is worth knowing the study exists, and worth knowing how small it is.
Botulinum toxin units are not interchangeable between brands. Every FDA toxin label says so explicitly: units of Dysport cannot be converted into units of any other product, and the same wording appears on the Jeuveau, Daxxify and Letybo labels. A dose figure without a brand name attached is not a usable dose.
That is a real problem in this literature. The gummy smile trials do not consistently name which toxin brand they used. A double-blind randomised trial of 49 patients compared injecting at the "Yonsei point" against conventional injection into the levator labii superioris alaeque nasi, using a total of 6 units split 3 units per side — but the brand is not stated, so those units belong to no scale. Another randomised preliminary trial compared four injection points against two, at 2 units per point, and again did not name the brand. The 2026 systematic review reports doses of 2 to 7.5 units per side across its included studies with the brand unspecified.
So the pattern is consistent — small doses, into one or two lip-elevator muscles — but there is no brand-anchored dose you can quote: If you are told a number at a consultation, the question worth asking is which brand's units it is in.
Two findings from those trials are useful anyway. The 49-patient randomised trial found gum show reduced at 4, 12 and 24 weeks and back to baseline at 48 weeks in both groups, with no difference between them — so the more fashionable injection point was not better. It was funded by the National Natural Science Foundation of China and a university hospital, not by a manufacturer. The other trial found that adding injection points prolonged the effect (about 25 weeks versus 16 weeks) but did not make it stronger; its authors call their own results preliminary because of high dropout.
Lip repositioning surgery removes a strip of tissue from inside the upper lip and reattaches the lip lower down, limiting how far it can ride up. It is done under local anaesthetic, usually by an oral surgeon or periodontist.
The best comparative source is a 2026 systematic review of 17 studies and 576 patients — 179 treated with toxin alone, 317 with lip repositioning surgery and 80 with both.
Botulinum toxin alone: Baseline gum show 5.1 to 6.9 mm, peak reduction 3.0 to 4.2 mm, relapse 70 to 90 percent
Conventional lip repositioning surgery: Baseline 4.8 to 6.2 mm, peak reduction 3.5 to 4.5 mm, relapse 40 to 60 percent
Modified surgery: (adding a small muscle cut or anchoring stitches to the bone lining): relapse 20 to 35 percent
Toxin combined with surgery: relapse 10 to 20 percent
The review reported no major adverse effects across all three. Its limits matter: the included studies are heterogeneous, mostly not randomised, and the toxin brand is again unspecified. Surgery is also not reversible in the way an injection is, it leaves a scar inside the lip, and it does nothing for a skeletal cause.
Every filler risk applies, plus two things specific to the region.
The area around the base of the nose is a vascular danger zone: The angular and facial arteries run there, and they connect back to the arteries that supply the eye. If filler is pushed into one of those arteries it can travel backwards and then forwards into the retinal circulation. In a review of 511 published cases of blindness after filler spanning more than a century, the nose accounted for 40.6 percent of the 365 most recent cases, the forehead 27.7 percent and the glabella 19.0 percent. Of 318 cases with a documented outcome, 6.0 percent recovered completely, 25.8 percent improved partially and 68.2 percent did not recover. These are counts of published cases, not a rate — nobody knows how many injections are performed, so this cannot be turned into a personal percentage. What it does establish is that when it happens, it is usually permanent.
Filler does not address muscle overactivity at all: In the classic hypermobile-lip patient it is treating the wrong mechanism, which is a reason results can disappoint even when the injection itself goes perfectly.
The ordinary risks are bruising, swelling, tenderness, lumps and asymmetry. In FDA pivotal trials of hyaluronic acid fillers these injection-site responses were common and mostly settled within a week.
One thing does work in filler's favour: Juvederm is hyaluronic acid, so it can be broken down: An injection of hyaluronidase, an enzyme that splits hyaluronic acid, dissolves it — usually within minutes to hours. That is also the emergency treatment if a blood vessel is blocked. Two caveats belong beside it. Dissolving filler is an off-label use of hyaluronidase in the US: the Hylenex label lists only fluid administration, drug dispersion and urography as approved uses. And hyaluronidase is not a reliable rescue for filler-related blindness — in the 511-case review, no treatment showed a statistically significant association with visual improvement.
Questions worth asking at a consultation:
Which cause of gum show do you think I have — muscle, jaw, gum tissue, or lip length?
If it is muscular, why would you inject filler rather than toxin?
If you are recommending toxin, which brand and how many of that brand's units?
What is the plan if the result is asymmetric or my lip feels heavy?
Do you stock hyaluronidase on site?
Would a dental or oral surgery opinion change what we do?
Go to an emergency department or call 911 if any of these happen during or after an injection. They can mean filler has entered a blood vessel, and time is measured in hours.
Any change in vision: Blurring, a dark patch, double vision or loss of sight in one eye
Sudden severe pain, or pain out of proportion to the injection
Skin turning white (blanching), then dusky, purple, grey or net-like and mottled
Weakness, drooping, slurred speech, confusion or any other stroke-like symptom
Do not wait for a routine appointment and do not wait to see if it settles overnight.
Swelling keeps growing after the first few days instead of settling
A lump appears and does not soften over a couple of weeks
Redness spreads outward from the injection site
Tenderness, firmness or swelling appears weeks or months later, which can be a delayed inflammatory reaction or an infection
Your smile is noticeably uneven, or the upper lip feels heavy or hard to control
The filler seems to have moved from where it was placed