Gummy smile Botox overcorrected: why, how long and what to do

A gummy smile is a smile that shows a lot of gum above the teeth. When it is caused by muscles that lift the upper lip too much, botulinum toxin can relax them so that the lip rises less¹. If the correction is too strong, the lip comes down too far: the smile looks flat, less expressive, sometimes crooked. This is one of the smile problems after an injection. The effect is bothersome, but it is temporary and fades over the weeks.

Why can a gummy smile be overcorrected?

Several small muscles lift the upper lip when you smile: the levator labii superioris, the levator labii superioris alaeque nasi (which also lifts the side of the nostril) and the zygomaticus minor. These are the muscles treated for a gummy smile². If they are relaxed too much, the lip no longer rises enough: it covers more of the teeth, and the smile loses its range.

Several factors can contribute:

• the origin of the gummy smile: it can be linked to the bone structure, the gums or the muscles, and the toxin only acts on the muscular component⁷. A meta-analysis stresses that lip length must be assessed before treatment to avoid complications²;
• the dose and injection point: a review of nasal aesthetics notes that injecting the muscle that lifts the lip and the side of the nostril can lengthen the upper lip⁵;
• asymmetry: the two sides do not always respond in the same way. An asymmetric smile is among the complications reported, along with pain at the injection site, swelling and bruising². In a series of 16 patients, an asymmetric smile and difficulty smiling were each observed once⁴.

Treating a gummy smile is not an indication in the French product labels, which provide in aesthetic use only for frown lines and, depending on the product, crow’s feet and the forehead⁸: it is an off-label use.

How soon after the injection does it appear?

It appears as the effect of the toxin builds up, usually within the first week⁹. According to a meta-analysis of 17 studies, the reduction in exposed gum is clear from week 2³: this is often when you can judge whether the correction is too strong.

How long does it last?

It follows the effect of the toxin. In the meta-analysis mentioned, the effect holds for at least 12 weeks, then returns close to baseline around week 24³. In a pilot study of five patients, the improvement lasted 3–6 months¹. An overcorrection gradually fades during this period, at the pace of the product’s effect. The page on how long botulinum toxin lasts explains what the duration of action depends on.

Is it reversible?

Yes. The lip gradually regains its movement as the treated muscles recover their strength, and the smile returns close to how it was before treatment³. The meta-analysis on gummy smile observes this gradual return towards baseline values in the studies it included³.

Is there a treatment?

No product reverses the effect of the toxin: a lip that sits too low corrects itself with time. When there is an asymmetry, a small additional injection can sometimes rebalance the smile: in a series of 16 patients, two mild side effects were corrected with additional doses⁶. This level of evidence is low, and the decision rests with the doctor, after an examination. No massage or exercise has shown any effect in the sources we consulted.

What should you avoid?

• Do not ask for an extra injection to "lift" the lip: adding toxin relaxes the muscles further, and weakness can be made worse by another toxin injected before the effect of the previous one has worn off⁹.
• Do not judge the result too early or too late: the effect changes over the first few weeks³.
• Do not try to compensate with a lip filler without medical advice.

When should you see a doctor?

Talk to the doctor who performed the injection if your smile bothers you, if you have trouble closing your mouth, eating or speaking clearly, or if the problem does not improve. Dated photos, at rest and smiling, will help track how it evolves. Difficulty swallowing, a changed voice or difficulty breathing are warning signs that mean calling emergency services (15 or 112 in France, or your local emergency number).

If your smile looks mainly different or less natural, see the page on the smile that has changed after an injection. If the injection was along the edge of the lip, the page on a lip flip gone wrong is more relevant.