Botox gummy smile: when too much gum shows on smiling

The smile is one of the eleven areas of our "why and how" guide to botulinum toxin. This page is about the gummy smile: its causes, what the toxin can and cannot do, what studies show, and why it is an off-label use in France. It does not replace a consultation.

Why is a gummy smile treated?

A gummy smile is when a large band of gum above the upper teeth shows on smiling. It has several possible causes: an upper jaw that is too long vertically, teeth that have not fully erupted, thick gums, or muscles that lift the upper lip higher than average². An individual diagnosis is therefore essential².

Botulinum toxin only addresses the last cause: overactive muscles lifting the upper lip^1,2. By relaxing them temporarily, the lip rises less on smiling and shows less gum. The muscles most often targeted in studies are the levator labii superioris, the levator labii superioris alaeque nasi and the zygomaticus minor².

What the toxin does not do: it does not correct a gummy smile caused by the shape of the jaw bones or by the gums themselves. When the upper jaw is too long, a meta-analysis points out that the reference solution is surgery².

When is the toxin used?

Studies concern people whose gummy smile is caused by muscle overactivity. The 2023 meta-analysis included studies of at least 10 patients with more than 2 mm of gum showing on smiling, and excluded gummy smiles due to other causes, such as incomplete tooth eruption or thick gums². There are no official criteria, since no French label provides for this area.

The contraindications in the labels apply whatever the area: allergy to the toxin or to a component of the product, a generalised disorder of the muscles and of the junction between nerve and muscle (myasthenia gravis, Lambert-Eaton syndrome), an infection at the injection site^3,4. Treatment is not recommended during pregnancy or breastfeeding^4,5.

Which toxin for a gummy smile?

The type A toxins approved for aesthetic use in France cover frown lines and, depending on the product, crow’s feet and forehead lines^3,5. None provides for the gummy smile. The short-acting botulinum toxin (serotype E) is approved for frown lines only, in the European Union and in Canada^4,6. For this area, any injection is therefore off-label. Published studies concern type A toxins^1,2.

Is it right for me?

The first step is to understand the cause of your gummy smile. This often requires an examination by a dentist or an orthodontist, in addition to the opinion of the doctor who performs the injection. If the cause is in the bone or the teeth, the toxin is not the right answer².

If the cause is muscular, your doctor will assess the symmetry of your smile, how much gum shows and your expectations. A meta-analysis notes that other options exist depending on the case: jaw surgery, gum surgery, orthodontics, or surgical repositioning of the lip, the latter carrying a risk of relapse in the first weeks².

Questions to ask your doctor: what causes my gummy smile? Is this treatment off-label? What result is reasonable? What happens if my smile becomes uneven? What alternatives are there in my case?

Onset and duration

No label gives an onset or duration for this area. In the 2023 meta-analysis, the reduction in visible gum was about 2.5 mm on average at two weeks and about 2.2 mm at three months². The effect gradually decreases but was still measurable at 12 weeks². In the 2005 pilot study, involving five patients, the improvement lasted 3–6 months¹.

To understand how the toxin works over time, see the page on how long botulinum toxin takes to work.

What are the risks in this area?

The area around the mouth is made up of muscles used to smile, speak and eat. A type A label points out, for a neighbouring area, that an injection too close to the zygomaticus major can make the lip droop³. The 2023 meta-analysis set out to study complications among its objectives²; its abstract gives no frequency. The injection-site reactions described in the labels (pain, swelling, small bruise) are also possible⁴.

The neighbouring lips have their own page on botulinum toxin and the lips, and the upper nose a page on bunny lines.

Difficulty swallowing, speaking or breathing requires immediate medical attention⁴. If your smile seems different after an injection, the page on the smile after an injection describes the most common situations.