Botulinum Toxin for Bunny Lines

What Is Botulinum Toxin for Bunny Lines?

Botulinum toxin for bunny lines is a treatment for the lines that appear on the upper part of the bridge of the nose and at the root of the nose (where it meets the area between the brows) when you scrunch up your face or laugh. The aim is to temporarily reduce the movement of the muscles that cause these lines. In everyday language, botulinum toxin is often called Botox®, a word that comes from a product name; the active ingredient is botulinum toxin type A.

The lines are linked with contraction of the nasal muscle (nasalis), which covers the sides of the bridge of the nose. An anatomical study showed that the thin skin between the inner corner of the eye and the bridge of the nose is also affected by several surrounding muscles: the procerus muscle between the brows, the muscle that encircles the eye, and the muscle that lifts the upper lip and the wing of the nose. These muscles are among the injection targets; when the anatomy of the area is not well understood, the treatment becomes more difficult.

The effect comes about in the same way as in other areas of the face: small amounts of botulinum toxin injected into an overactive muscle relax that muscle locally, and the skin over it smooths out. According to a review of cosmetic treatments, the result is more noticeable on lines that appear with movement than on lines that are also visible when the face is at rest. You can find the general properties of the toxin, how long its effect lasts and its general risks on the botulinum toxin page.

RELATEDBotulinum Toxin

SOURCEPMID 39711041PMID 35622589PMID 42202343

What Does ‘Bunny Lines’ Mean?

In English, ‘bunny lines’ simply means ‘rabbit lines’. The name comes from the way the lines that appear on the bridge of the nose when you scrunch up your face resemble a rabbit wrinkling its nose. It is not a medical classification but an everyday comparison; in Turkish, these lines are usually called nose lines or nose wrinkles.

Scientific publications use different names for the same lines: nasal wrinkles, transverse nasal lines or nasal dorsum lines. One anatomical study describes them as vertical and diagonal wrinkles linked to contraction of the nasal muscle. A study in Asian patients classified these lines into four types according to their distribution: complex, horizontal, diagonal and vertical.

Although the names differ, they refer to the same place: the thin skin between the inner corner of the eye and the bridge of the nose, and on the upper part of the bridge. The direction and spread of the lines vary from person to person. In other words, ‘bunny lines’ is not a single line pattern but a shared name for the lines that appear with movement in this area. Your own line pattern is seen at the consultation, while your face is moving.

SOURCEPMID 39711041PMID 25921574PMID 36879432

Which Muscles Cause Bunny Lines?

There is no single muscle beneath bunny lines; the lines form in a border zone where several muscles meet. This is also why the treatment cannot be planned with the same pattern for everyone. This area has been studied using imaging in living volunteers, cadaver examinations and case series.

In a study that combined ultrasound and cadaver examination, a triangular area consistently free of muscle was found between the inner corner of the eye and the bridge of the nose, and it was named the ‘bunny triangle’. This area lies between the edges of the procerus, the nasal muscle, the muscle around the eye and the muscle that lifts the upper lip and the wing of the nose; its size and shape vary with the width of the procerus and the nasal muscle. The researchers suggest that an injection placed directly over the line may end up in connective tissue instead of muscle, and that the result may therefore be less than expected.

Another cadaver study found that some surface fibres of the procerus muscle joined the transverse part of the nasal muscle in all specimens. A connection between the procerus and the muscle that lifts the upper lip and the wing of the nose, however, was found only in some specimens; in other words, this connection varies from person to person.

A study in Asian patients also found connecting fibres between the muscles involved in bunny lines on cadaver examination; the researchers named this muscle group the dorsal nasal complex and described four anatomical variations. These variations matched the four line distribution types seen in patients. What this means for you in practice: the place where a line appears and the muscle that pulls it are not always in the same spot.

SOURCEPMID 39711041PMID 28132092PMID 36879432

Link With Lines at the Root of the Nose and Between the Brows

In scientific publications, bunny lines are often discussed not on their own but as part of treatments between the brows and in the upper face. There is an anatomical reason for this: the procerus muscle at the root of the nose lies between the frown-line area and the nasal muscle, and its fibres merge with those of the nasal muscle.

In a study that retrospectively reviewed photographs of 139 patients having treatment between the brows for the first time, contraction patterns between the brows were divided into five types. This classification looked at whether vertical and horizontal lines between the brows, bunny lines and forehead lines were present. In other words, bunny lines were treated as one finding within the assessment of the area between the brows.

In an older series, 250 patients treated for nasal wrinkles had injections into the nasal muscle only. The result was considered adequate in 40% of patients; in 60%, the lines partly remained. In 30% of patients the remaining lines were at the root of the nose, and in 30% they were at the root of the nose and between the eyes. The researchers reported that these lines improved with injections at additional points; however, this series had no control group for comparison.

In a single-centre retrospective study of whole-face treatments, bunny lines were among the areas treated in 283 (71.8%) of the 394 treatments given to 189 patients. Bunny lines are also one of the nine treatment areas defined in an international consensus statement on the mid and lower face. A review of cosmetic treatments in the oral and maxillofacial region (the mouth, jaws and face) lists bunny lines among the wrinkles caused by movement (dynamic wrinkles), together with lines between the brows, on the forehead, around the eyes and around the mouth.

SOURCEPMID 28132092PMID 24168325PMID 15841625PMID 31486568PMID 20569284PMID 36828397

How Strong Is the Evidence for Bunny Lines?

The short answer: the evidence specific to bunny lines is limited. The publications reviewed did not include any randomised, placebo-controlled trial (a trial in which participants are randomly assigned to groups and compared with a dummy treatment) looking only at this area. Most of the available data come from case series, retrospective reviews, expert consensus and anatomical studies.

The Cochrane review of botulinum toxin for facial wrinkles covers 65 randomised trials: 43 on frown lines, seven on crow’s feet (lateral canthal lines), two on the forehead, two around the mouth, one on the whole face and nine on more than two areas. The nose does not appear in this list as a separate area. As a result, data on bunny lines are largely contained within upper-face or whole-face treatments.

A systematic review of cosmetic treatments in the mid and lower face and neck could include only 10 of 560 articles, and only two of these gave data on nasal wrinkles. In the articles that reported effectiveness, the results were positive and no serious adverse effects were reported. However, these uses are largely off-label, meaning they fall outside the uses for which the product is officially approved; more research is also needed.

Even the largest series specific to this area have no control group. In a study in Asian patients, 349 treatments were given to 320 patients; a significant reduction in line severity was reported, and most patients were satisfied. These findings are a useful guide, but because they include no comparison with placebo or another method, they do not give a firm answer on how large the effect is.

SOURCEPMID 34224576PMID 33671800PMID 36879432

Approved Use or Off-Label Use?

In scientific publications, bunny lines are listed among the uses that fall outside the approved cosmetic uses (indications). This does not mean the treatment is forbidden or has never been tried; it means that the evidence and the product information do not specifically cover this area.

According to a review of cosmetic treatments, the approved cosmetic uses in the US are three areas of the upper face: frown lines, forehead lines and crow’s feet. A systematic review of the mid and lower face also describes these uses, including nasal wrinkles, as largely off-label. This is not a measure of quality; it only shows where the evidence stands.

In Türkiye, the licensed uses depend on the approved product information (summary of product characteristics) for the product being used. Before treatment, you can ask your doctor about the licensing status of the product to be used and whether its use for bunny lines is covered by its licence; this is a natural part of the consultation.

SOURCEPMID 42202343PMID 33671800

Limits of This Treatment

Botulinum toxin for bunny lines is a treatment aimed at muscle movement; its target is not the skin itself but the line created by the muscle. According to an international expert group, botulinum toxin should be considered the first-choice option when the main cause of the appearance you want to change is excessive muscle contraction. If something other than movement lies behind a line, the treatment does not act on that cause.

Research shows that facial wrinkles result from a combination of thinning of the skin and repeated contraction of the muscle underneath; the result is also more noticeable on lines that appear with movement (dynamic lines) than on lines that are visible when the face is at rest (static lines). For this reason, if you have lines on the bridge of the nose that have become etched into the skin and remain when your face is at rest, this treatment alone may not meet your expectations. The treatment may also not remove all the lines in the area in one step: in one case series, lines were reported to persist at the root of the nose or between the eyes in a large proportion of patients after treatment of the nasal muscle. This shows that line patterns differ from person to person.

The shape of the nose is a separate matter. A systematic review of 23 studies on the use of botulinum toxin in the nose area looked at uses such as a drooping nose tip, wide nostrils and small irregularities after rhinoplasty (nose surgery), and noted that larger studies are needed. In treatments for a drooping nose tip, the targets also include the muscle of the septum that pulls the nose tip downwards. These are separate treatments; the aim of treatment for bunny lines is not to change the shape of the nose. The effect is not permanent and wears off on its own over time; keeping it requires repeat treatments. Controlled studies measuring how long the effect lasts specifically in the nose area are limited; for this reason, no separate duration is given for this area.

RELATEDBotulinum Toxin or Fillers?

SOURCEPMID 26910696PMID 42202343PMID 15841625PMID 39376434PMID 37496386

Why Discuss the Upper Lip and Your Smile?

One of the muscles right next to bunny lines also helps move the upper lip. For this reason, with treatments around the nose, how your smile and upper lip may be affected is discussed separately. The Latin name of this muscle is levator labii superioris alaeque nasi, which means ‘the muscle that lifts the upper lip and the wing of the nose’.

This muscle is among the injection targets for bunny lines. In a series in which 227 patients were reviewed retrospectively, the distance between the upper lip and the nose when smiling was reported to shorten, and a drooping nose tip to improve, after whole-face treatment that also included the nasal muscles. The researchers explain this by the lip-lifting part of the muscle becoming relatively stronger when its nasal part relaxes. This is a series with a low level of evidence; even so, it suggests that treatment that also includes the nasal muscles can change how your smile looks.

An expert group links standard injection patterns that do not take a person’s anatomy into account with unwanted results such as a change in the shape of the smile and flattening of the cheek; the group recommends adjusting the dose, depth and injection site to each person. The mechanism behind these results is the spread of the toxin’s effect. Most local and distant complications of botulinum toxin are attributed to the effect spreading to nearby muscles in an unwanted way; this spread appears to depend mainly on the dose. However, the abstracts of the publications reviewed do not include data specific to this area on how often a drooping upper lip occurs after treatment for bunny lines.

SOURCEPMID 35622589PMID 38191864PMID 40585019PMID 23868503PMID 29016535

Known Risks

Treatment for bunny lines is a medical procedure using a prescription-only medicine, and it has side effects. Most of the reported effects are mild and temporary. The rates below come from other studies; they are not data from this clinic and cannot be used to calculate your personal risk.

Mild bruising and swelling can occur at the injection site. A temporarily drooping eyelid and a temporarily drooping brow are technique-related complications. According to the Cochrane review of facial wrinkles, treatment probably increases the risk of a drooping eyelid (ptosis); these data come mainly from studies of frown lines.

In a systematic review covering 8,787 people, lip asymmetry and imbalance were reported at a rate of 6.9% after lower-face treatments, and all of these were reported to have resolved on their own. According to a review of 20 studies on complications after facial treatments, facial asymmetry, impaired function around the mouth, local reactions and headache are usually mild and resolve on their own; systemic adverse effects (affecting the whole body) are rare. However, the evidence on this is limited.

In the retrospective study of whole-face treatments, in which bunny lines were also often treated, complications occurred in six of 189 patients (3.2%): in five, the effect spread from the chin muscle to the lower lip muscle, and in one, a drooping eyelid developed after upper-face treatment. No complication was attributed to treatment of bunny lines; however, because this was a single-centre retrospective review, this does not mean there is no risk. General contraindications (reasons not to have the treatment) and special situations are explained on the botulinum toxin page. Which symptoms after treatment mean you should contact the clinic will be explained to you at the consultation, according to the doctor’s own protocol.

RELATEDBotulinum Toxin

SOURCEPMID 42202343PMID 34224576PMID 24575858PMID 41640941PMID 31486568