Chin

What is botulinum toxin for the chin?

Botulinum toxin for the chin is a treatment in which botulinum toxin is injected into the mentalis muscle at the tip of the chin to reduce its movement temporarily. The aim is to soften the dimpled, bumpy look that appears in the chin skin when this muscle is overactive, and to ease strain in the chin. The treatment targets the muscle; it does not add volume to the tissue.

The mentalis is a paired muscle, one on each side, that starts from the part of the lower jawbone that holds the teeth (the alveolar bone). Anatomical studies show that this muscle is the main target of botulinum toxin when a bumpy chin is caused by an overactive muscle. In an expert consensus on the muscles of the lower face, the main uses for this muscle that reached strong agreement were the ‘orange peel’ (‘golf ball’) look and an overactive muscle.

It works in the same way as treatments in other areas of the face: small amounts of toxin injected into an overactive muscle relax that muscle locally and temporarily, so the skin it pulls on becomes smoother. According to a review of cosmetic treatments, wrinkles result from thinning of the skin combined with repeated contraction of the muscle underneath, and the results are more noticeable in lines that appear with movement. You can find more detail on how it works in general, the differences between products and repeat treatments on the Botulinum Toxin page.

In everyday speech, this treatment is often called ‘chin Botox®’. That name comes from a single brand, but there are several different products that contain the same active ingredient. The dose, dilution and injection points vary from person to person; the doctor giving the treatment decides on them.

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What does ‘orange peel’ chin mean?

An ‘orange peel’ chin is a bumpy look made up of small dips and bumps that appear in the chin skin when the chin muscle contracts. The same appearance is also called ‘peau d'orange’ (French for ‘orange peel’), ‘golf ball’ chin and ‘cobblestone chin’.

These names describe an appearance, not a disease: the visible creases that form in the chin when the mentalis muscle contracts. Because the appearance is linked to muscle contraction, it is assessed separately with the face at rest and in motion. Bumpiness that appears when the lips are pressed tightly together may not be the same problem as an irregularity that is still there when the face is at rest.

The anatomical basis of this bumpiness is not yet well understood. A small anatomical study of six cadavers identified three separate groups of fibres in the mentalis muscle: horizontal fibres that attach to the chin skin and support the lower lip, vertical fibres that run down to the lower edge of the jaw, and oblique fibres that attach to the skin at individual points. The bumpy look was linked to these point-like attachments of the oblique fibres, while the horizontal fibres, which form thick bundles, were not found to cause surface irregularities.

Although the study was small, it has a practical implication: if the bumpiness in the chin comes from the muscle underneath pulling on the skin, it is a muscle problem. If there is another cause, such as a lack of volume in the chin, thinning skin or a scar, the problem is different even if the appearance is similar, and the solution may be different too.

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How does the chin muscle work?

The mentalis is a small but functional muscle that affects both the position of the lower lip and the shape of the chin tip. According to a study of the muscles that control the lower lip, the position of the lower lip is set jointly by the mentalis, the muscle that pulls the lower lip down, the muscle that pulls down the corners of the mouth and the platysma (the thin, flat muscle at the front of the neck); this position is fundamental to smiling and to how the mouth works.

In 45 patients who had surgery for involuntary linked movements of the face (synkinesis), nerve maps made during the operation showed that the mentalis muscle receives signals not from a single nerve branch but from several branches of the facial nerve. According to an anatomical review of the mentalis muscle, when the anatomy of the muscle and the properties of the toxin are not well enough understood, side effects can occur, such as the mouth not closing fully or an asymmetric smile caused by a drooping lower lip.

The shape of the muscle also differs from person to person. In a cadaver study of 44 half-faces, the mentalis muscle was dome-shaped in three dimensions in 38 samples and flat in 6; in young volunteers, the depth of the muscle under the skin and its thickness were also measured with imaging. The researchers say this information may help to determine an effective and safe injection point and depth.

In practice, this means the chin muscle supports both the chin tip and the lower lip. Relaxing the muscle can reduce the pull on the chin skin; however, if this relaxation spreads to lip function, it can cause an unwanted result. This balance sets the chin apart from areas such as the forehead or between the brows, and explains why the treatment is planned for each person individually.

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Chin strain and lip closure

Chin strain is when the chin muscle works harder than usual as the lips close, and the chin tip puckers and tightens. This is not always just a muscle habit; the structure of the teeth or jawbone may lie behind it. So the cause of the strain is looked into first: is it the muscle, the structure, or both?

In orthodontics (the treatment of irregular teeth and jaws), this has been studied under the name ‘soft-tissue chin strain’. A study of 209 women aged 18 to 30 found that the further forward the upper front teeth were positioned, and the greater the horizontal distance between the upper and lower front teeth, the more likely chin strain was when the lips closed. The researchers concluded that orthodontic treatment should target these measurements to reduce the strain.

The same topic is addressed in aesthetics. A systematic review of aesthetic uses of botulinum toxin other than for wrinkles listed chin muscle strain and a receding chin among its targets on the face. However, the review's summary does not give an effect size specific to the chin muscle; it assesses different targets together.

In short, if chin strain is caused by the muscle itself, botulinum toxin can reduce this contraction. If the cause is that the teeth or jaw structure make it hard for the lips to close comfortably, relaxing the muscle does not remove that cause. In that case, an assessment by a dentist or orthodontist is a separate matter and may come up at your consultation.

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A receding chin: muscle or volume?

A chin that looks set back is usually related to volume or bone structure; in some people, however, an overactive chin muscle can make this look more pronounced. Among non-surgical methods, fillers and collagen stimulators address a chin tip that sits back and volume loss, whereas botulinum toxin targets an overactive muscle.

According to a case series, the position of the chin tip is not determined by bone alone: in some people whose chin looks set back, a high-positioned, overactive mentalis muscle blunts the chin line. In this series, 11 patients received botulinum toxin to the chin muscle only. In 10 of them, the most forward point of the chin tip was lower on photographic measurement, while the change in its forward position was not statistically significant. The series had no control group, meaning no group set aside for comparison.

A randomised trial (one in which patients are randomly assigned to groups), where the people assessing the results did not know who was in which group, noted that patients with a receding chin often have increased tension in the chin muscle. In this trial, 50 patients with a moderate to severe receding chin were assigned either to a group given botulinum toxin together with hyaluronic acid (HA) filler or to a group given filler only, and were followed up for 9 months. Receding-chin scores stayed similar in the two groups. In the combined treatment group, the filler's surface-volume coefficient was higher in the first 6 months, and the overall aesthetic improvement response was higher in the first 3 months.

In a retrospective study of 46 patients (one that looked back at past records), chin projection, meaning how far the chin sticks out, improved to a similar extent in both groups; the group that had botulinum toxin injected into the chin muscle first was reported to need less additional filler. Another study, of ten women and with no control group, used botulinum toxin together with calcium hydroxylapatite (CaHA). Although these studies point in a direction, they are small, their follow-up periods are limited and some of them are retrospective.

In short, the main issue with a receding chin is volume and bone structure; this is covered on the Chin and Jawline Filler page. In research, botulinum toxin mostly appears here as an option alongside filler for people whose chin muscle is overactive.

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How strong is the evidence?

Botulinum toxin for the chin is a treatment included in expert consensus statements and reviews; however, no placebo-controlled study (one comparing it with a dummy treatment) specific to the chin muscle was found in the sources searched. Most of the information is based on expert opinion, anatomical studies and small case series.

The expert consensus on the lower face muscles is a study in which 14 experts sought agreement over three rounds; it also reviews 16 previously published international consensus statements. The experts stress that, because the muscles in this area have important functions, the risk of side effects and complications is higher in the lower face, and that treatment there is therefore particularly difficult. Consensus statements bring experience together, but they do not prove effectiveness the way a controlled study does.

The systematic review of aesthetic uses of botulinum toxin other than for wrinkles covers 38 studies and 1,903 patients; most of the treatments were in the lower face. In these studies, satisfaction was high and few complications were reported. Even so, the researchers say that standard protocols and better assessment methods are needed to support decision-making. These uses are also off-label, meaning they fall outside the uses covered by the product's licence or approval.

It is also important to know the approval status. According to a review of cosmetic treatments, the approved cosmetic uses in the US are lines in the upper face: frown lines between the brows, forehead lines and crow's feet at the outer corners of the eyes; the chin area is not on this list. Before treatment, you can ask which uses the licence of the product to be used covers in Türkiye.

As for how long the effect lasts, the study abstracts searched contain no data specific to the chin. In general cosmetic use, the effect has been reported to develop fully in about two weeks and to last three to four months. A retrospective study of 400 patients at a single institution reported that results lasted longer than the drug's expected duration of effect in patients who had the lower face treated as part of full-face treatments repeated at regular intervals. The researchers explain this as the muscle functionally retraining; however, this is a hypothesis and has not been shown in a controlled study.

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Limits of this treatment

Botulinum toxin for the chin is a muscle treatment: it reduces the movement of the chin muscle, but it does not add volume to the chin, does not change the bone structure and is not permanent. If your chin concern has a cause other than the muscle, the treatment has no effect on that cause and will not meet your expectations.

According to a review of non-surgical methods in this area, ageing here progresses through volume loss, tissue laxity and bone loss; botulinum toxin, by contrast, softens lines that appear with movement by reducing an overactive muscle. However, non-surgical methods are not a substitute for surgery, and their effects are temporary.

In concrete terms, this limit means the following: if the chin sits back because of volume or bone structure, botulinum toxin does not bring the chin forward; in the randomised trial on receding chins, too, the toxin was used alongside filler, not instead of it. If straining to close the lips is caused by the structure of the teeth or jaw, relaxing the muscle does not change that structure. Fullness under the chin and jowls (sagging along the jawline) are separate issues.

This information is given not to steer you towards one method but to help you compare the options. Which route makes sense for you — botulinum toxin, filler, an assessment by a dentist or orthodontist, a surgical option or none of these — is decided by the assessment at your consultation and by your own decision.

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Known risks

With botulinum toxin treatment in the chin, the most discussed risk is an effect on lower lip function. Because the chin muscle also supports the lower lip, if the effect spreads to this function, it can cause lip asymmetry or an inability to close the mouth fully. The figures below come from other studies; they cannot be used to calculate your personal risk.

According to an anatomical review of the mentalis muscle, when the properties of the muscle and the toxin are not well enough understood, side effects can occur, such as the mouth not closing adequately and an asymmetric smile caused by a drooping lower lip. A systematic review of the safety of aesthetic botulinum toxin treatments, covering 8,787 people, reported lip asymmetry and imbalance at a rate of 6.9% after lower-face treatments, and stated that all of these effects resolved on their own. This figure applies to the whole lower face, not only the chin.

The expert consensus on the lower face also stresses that the risk of side effects and complications is higher in this area because its muscles have important functions. The experts also state that when the nearby muscle that pulls down the corners of the mouth is treated, spread of the toxin to the muscle that pulls the lower lip down should be avoided. This shows how close together the muscles around the lips are.

An unexpected outcome has also been reported. In a case report, a person treated in the mentalis muscle for a bumpy chin developed a bulge in the chin on the second day, the opposite of what was expected (paradoxical bulging). This was attributed to uneven relaxation of the muscle, and the problem was reported to have resolved after additional treatment of the fibres that were still overactive. This is a single case and gives no information about how often it happens.

There are also more general risks. In the 400-patient lower-face series, mild adverse effects were reported in fewer than 12% of patients, mostly bruising and discomfort; no serious complications were seen. In the receding chin study, adverse effects were also mild and resolved within 7 days. The symptoms after treatment that mean you should contact the clinic are set by the doctor's own protocol and are explained to you at your consultation.

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Situations that need special care

The general precautions known for botulinum toxin also apply to the chin. The situations below are those highlighted in the scientific literature; they are not a list of situations in which the clinic does not give treatment. The situations in which treatment will not be given depend on the doctor's own assessment and are discussed at your consultation.

In cosmetic botulinum toxin treatment, neuromuscular disorders such as myasthenia gravis, a tendency to form keloids (raised scars that grow excessively) and allergy to any of the product's ingredients are listed among the reasons not to have the treatment (contraindications). A systematic review of the link with myasthenia gravis reported that eight people with myasthenia that had not yet been diagnosed were treated, and all eight developed marked muscle weakness. If you have a known neuromuscular disorder or unexplained muscle weakness, mention it at your consultation.

According to a recent review of cosmetic procedures during pregnancy and breastfeeding, optional (elective) cosmetic procedures are postponed during pregnancy, while during breastfeeding an individual risk assessment is made. These two periods should not be treated in the same way. At your consultation, you need to say whether you could be pregnant and whether you are breastfeeding.

Involuntary trembling of the chin is a separate condition. Geniospasm is a rare and usually benign movement disorder that causes involuntary trembling of the chin muscle in episodes. A systematic review covering 41 publications and 489 people found a family history (the same condition in other family members) in the great majority of people, and reported that the condition usually does not respond to treatments other than regular botulinum toxin injections. This is a neurological matter, not an aesthetic one, and is assessed separately.

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