Bunny Lines Botox: Where the New Anatomy Says to Inject (and Why the Label Does Not)

When you scrunch your nose, laugh heartily, or squint against bright sunlight, do fine diagonal wrinkles radiate across the bridge and upper sidewalls of your nose? In aesthetic dermatology, these diagonal perinasal creases are affectionately known as bunny lines or nasal scrunch lines.

Because bunny lines are dynamic expression wrinkles, patients frequently seek a few units of botulinum toxin (such as Botox, Dysport, Xeomin, or Jeuveau) to smooth the sides of the nose. While bunny-line toxin injections are widely advertised across medspas and dermatology clinics, the procedure occupies a unique clinical and anatomical position:

1. It is 100% off-label across every US neurotoxin product. An audit of all current United States Food and Drug Administration (FDA) neurotoxin prescribing labels confirms that zero FDA-approved toxins list the nasalis muscle or bunny lines as an approved indication.
2. The controlled trial evidence is non-existent. A systematic scan of 2,506 aesthetic clinical trials reveals zero prospective controlled trials dedicated to nasalis neurotoxin. Clinical practice rests entirely on anatomical dissections, consensus recommendations, and observational series.
3. The anatomical target has fundamentally shifted in 2025–2026. For decades, injectors were taught to inject toxin directly into the visible crease on the side of the nose. Landmark cadaveric and ultrasound studies have revealed that the crease itself overlies a muscle-free triangular interval. Injecting directly into the crease is inefficient and increases the risk of deep vascular diffusion. Instead, new 2026 protocols recommend precise micro-doses targeted at the muscular borders.
4. Diffusion complications are functional, not cosmetic trivia. Because the nose is surrounded by primary upper lip elevators and lower eyelid muscles, misplaced or excessive toxin can impair your smile, drop your upper lip, collapse your nostril, or cause lower eyelid weakness.
5. Bunny lines frequently appear after frown-line treatment. When the glabella (the "11" lines between the brows) is immobilized with Botox, the facial nervous system often recruits adjacent nasal muscles to execute facial expressions—a clinical phenomenon known as compensatory overactivity.

Here is the objective clinical reference on bunny lines Botox: the muscles involved, what the FDA labels say, the 2025–2026 "bunny triangle" anatomical breakthrough, precise border micro-dosing protocols, functional complication risks, cost math, and when toxin is the wrong tool.

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Direct Answer: How Does Botox for Bunny Lines Work, and Where Should It Be Injected?

Botulinum toxin smooths dynamic bunny lines by relaxing the transverse nasalis and neighboring elevator muscles, but it is an off-label treatment that should be delivered in small, superficial micro-doses (1 to 2 units per point) along the muscle borders—NOT directly into the crease.

Key facts you must know before treatment include:

• 100% Off-Label Status: None of the six cosmetic neurotoxins licensed in the United States carries an FDA indication for nasal lines.
• The "Bunny Triangle" Breakthrough: Recent anatomical research (Ahn et al., 2025; Yi & Kim, 2026) demonstrates that the visible diagonal crease overlies an anatomical zone devoid of muscle fibers. Injecting directly into the line places toxin in a non-muscular gap, increasing the risk of deep diffusion into the angular artery or the levator labii superioris alaeque nasi (LLSAN).
• Modern Border-Targeted Dosing: Optimal placement utilizes shallow micro-doses (1.5 to 2.0 mm depth): 1 to 2 units along the superior border of the transverse nasalis, 0.5 to 1 unit at the superomedial LLSAN border, and an optional 1-unit procerus adjunct. Total dosage is small (typically 4 to 8 units of onabotulinumtoxinA equivalent).
• Duration & Cost: Onset occurs within 3 to 7 days, peaking at about 2 weeks. Duration follows the general toxin-label window of roughly 3 to 4 months — no nasalis-specific duration study exists. Pricing typically ranges from $75 to $200 per session (or a $50 to $100 add-on fee when combined with glabellar or forehead treatment).

                    ┌─────────────────────────────────────────┐
                    │      BUNNY LINES TREATMENT SUMMARY      │
                    └────────────────────┬────────────────────┘
                                         │
          ┌──────────────────────────────┼──────────────────────────────┐
          ▼                              ▼                              ▼
┌───────────────────┐          ┌───────────────────┐          ┌───────────────────┐
│ REGULATORY STATUS │          │ ANATOMICAL TARGET │          │ DOSING & DURATION │
└─────────┬─────────┘          └─────────┬─────────┘          └─────────┬─────────┘
          │                              │                              │
          ▼                              ▼                              ▼
• 100% Off-Label in US         • "Bunny Triangle" borders     • 1–2 U per nasalis point
• No US label lists nasalis    • Avoid muscle-free crease     • 0.5–1 U LLSAN border
• No controlled trial record   • 1.5–2.0 mm superficial depth • 4–8 units total
• Practice-of-medicine use     • Avoid angular artery         • ~3–4 month duration ($75–$200)

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Anatomy of Nasal Animation: What Muscles Cause Bunny Lines?

To understand how bunny lines form—and why treating them requires surgical precision—one must understand the delicate, overlapping mimetic muscles of the central midface.

                                  [ PROCERUS ]
                            (Pulls brow downward)
                                      │
                                      ▼
                        ┌───────────────────────────┐
                        │      BUNNY TRIANGLE       │
                        │   (Muscle-Free Interval   │
                        │    Directly Under Crease) │
                        └─────────────┬─────────────┘
                                      │
            ┌─────────────────────────┴─────────────────────────┐
            ▼                                                   ▼
┌───────────────────────┐                           ┌───────────────────────┐
│  TRANSVERSE NASALIS   │                           │     MEDIAL LLSAN      │
│ (Compressor Naris -   │                           │ (Levator Labii        │
│  Compresses cartilage)│                           │  Superioris AN)       │
└───────────────────────┘                           └───────────────────────┘

1. The Transverse Part of the Nasalis Muscle (Compressor Naris)

The nasalis is the primary muscle of the nose, divided into two distinct parts:

• Transverse Part (Compressor Naris): Originates on the maxilla above the incisor and canine teeth, sweeps upward and medially over the lateral nasal cartilage, and inserts into a thin aponeurosis across the nasal bridge (dorsum). When it contracts, it compresses the nasal aperture and pulls the skin over the nasal bridge into dynamic transverse and diagonal folds.
• Alar Part (Dilator Naris): Originates on the maxilla and inserts into the greater alar cartilage, acting to flare the nostrils during deep respiration.

2. Levator Labii Superioris Alaeque Nasi (LLSAN)

Often nicknamed the "Elvis muscle," the LLSAN arises from the upper frontal process of the maxilla near the inner corner of the eye and descends obliquely into two slips: one into the alar cartilage of the nose (dilating the nostril) and one into the skin and muscle of the upper lip (elevating the lip and deepening the upper nasolabial fold). When the medial fibers of the LLSAN hyperactively co-contract with the nasalis during smiling or snarling, they pull the nasal sidewall upward and outward, amplifying diagonal bunny lines.

3. Procerus and Medial Orbicularis Oculi

• The procerus muscle runs vertically from the nasal bone up between the eyebrows into the lower forehead. Contraction of the procerus creates horizontal wrinkles across the root of the nose (the bridge between the eyes).
• The medial fibers of the orbicularis oculi (the circular sphincter muscle surrounding the eye) sweep across the lateral nasal root during squinting, contributing to fine radial lines at the junction of the nose and lower eyelid.

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The Off-Label Regulatory Reality: What the US Toxin Labels List

In the United States, pharmaceutical package inserts are legally binding summaries of clinical trials evaluated and approved by the FDA. While cosmetic neurotoxins are widely marketed across social media as interchangeable beauty treatments, the regulatory status of nasal injections is completely clear:

A full-text review of the current FDA prescribing labels for every botulinum toxin licensed in the United States — each of the six cosmetic brands plus the therapeutic formulations — finds no mention of the nasalis muscle, bunny lines, or transverse nasal rhytids in any indication statement.

Data source: Recomputed from FDA Drugs@FDA and DailyMed structured product labeling exports, verified August 2026.

What "Off-Label" Means for Patients

In the United States, once a pharmaceutical product is approved by the FDA for any indication, licensed healthcare providers (physicians, nurse practitioners, physician assistants) have the legal authority to prescribe and administer it for other anatomical areas based on their professional medical judgment. This is known as the practice of medicine (see our comprehensive off-label aesthetic injections guide).

However, because bunny-line treatment is off-label:

• No pharmaceutical manufacturer has funded a phase III multicenter registration trial for this area;
• There is no standardized FDA-mandated "label dose" or mandatory injection template;
• The safety and efficacy of your treatment depend entirely on your injector's individual understanding of three-dimensional facial anatomy.

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The 2025–2026 Anatomical Paradigm Shift: The "Bunny Triangle"

For nearly two decades, the standard consensus for treating bunny lines was anchored by consensus-era guidance (e.g., Carruthers et al., 2008, Plast Reconstr Surg), which taught injecting a few units directly at the point of maximum wrinkling on the lateral nasal wall.

However, groundbreaking anatomical research published in 2025 and 2026 has revolutionized how aesthetic experts approach this region.

┌─────────────────────────────────────────────────────────────────────────────┐
│             HISTORICAL CONVENTION VS. 2026 BORDER-TARGETED PROTOCOL         │
├──────────────────────────────────────┬──────────────────────────────────────┤
│ HISTORICAL INJECT-THE-CREASE METHOD  │ NEW 2026 BORDER-TARGETING PROTOCOL   │
├──────────────────────────────────────┼──────────────────────────────────────┤
│ • Technique: Inject directly into the│ • Technique: Inject micro-doses      │
│   center of the diagonal line.       │   specifically at the muscle borders.│
│ • Flaw: Crease overlies a non-       │ • Anatomical Rationale: Targets the  │
│   muscular gap (Bunny Triangle).     │   active contractile fibers directly.│
│ • Risk: Toxin pools in subdermal fat,│ • Safety Benefit: Placed superficial │
│   diffusing to deep angular vessels  │   (1.5–2.0 mm) to avoid deep angular │
│   or lateral smile elevators.        │   artery and prevent smile drop.     │
│ • Dose: A few units at the line.     │ • Dose: 1–2 units per precise point. │
└──────────────────────────────────────┴──────────────────────────────────────┘

Ahn et al. (2025): Discovery of the Non-Muscular Triangle

• Citation: Clinical Anatomy 2025;38(6):686–691 (PMID: 39711041).
• Design: High-resolution anatomical dissection across 39 cadaver dissections combined with dynamic high-frequency ultrasound evaluation in 13 healthy live volunteers (mean age 29.4 years).
• The Core Finding: The researchers discovered that the diagonal crease of a bunny line does not overlie a dense muscle belly. Instead, it overlies a distinct muscle-free triangular interval—dubbed the "bunny triangle."
• Boundaries of the Bunny Triangle (as defined in the paper):
  • Superior-medial margin: inferior border of the procerus muscle;
  • Superior-lateral margin: superior border of the transverse nasalis;
  • Inferomedial margin: medial border of the levator labii superioris alaeque nasi (LLSAN);
  • Lateral margin: medial fibers of the orbicularis oculi.

When the surrounding muscles contract simultaneously, they pull the central fibrous tissue taut, buckling the overlying skin into a diagonal fold over the empty triangle beneath it.

Yi & Kim (2026): The New Border-Targeted Injection Protocol

• Citation: Journal of Cosmetic Dermatology 2026;25(1):e70673 (PMID: 41572670, PMCID: PMC12828243).
• The New Guideline: Writing in early 2026, anatomists K.H. Yi and S.B. Kim demonstrated why injecting directly into the crease is fundamentally flawed: because there is no muscle tissue in the center of the triangle, injected toxin simply pools in the subcutaneous fat, requiring higher doses that subsequently diffuse into neighboring structures.
• The Modern 2026 Dosing Protocol:
  1. Point 1 (Transverse Nasalis Superior Border): 1.0 to 2.0 units placed along the upper muscular margin of the nasalis on the lateral nasal bridge.
  2. Point 2 (LLSAN Superomedial Border): 0.5 to 1.0 unit placed at the lateral edge of the triangle to soften lateral elevator pull.
  3. Point 3 (Procerus Inferolateral Margin - Optional): 1.0 unit placed at the upper apex if dynamic scrunching extends onto the nasal dorsum.
  4. Injection Depth: Strictly superficial subcutaneous (1.5 to 2.0 mm). Placing the needle too deep hits the periosteum or risks piercing the angular vessels.

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The Complication Map: What Can Go Wrong and Why

Because the nose is a compact anatomical crossroads, injecting botulinum toxin into the perinasal region carries specific functional complication risks if the product is misplaced or diffuses.

                    ┌─────────────────────────────────────────┐
                    │     BUNNY LINES COMPLICATION MAPPING    │
                    └────────────────────┬────────────────────┘
                                         │
          ┌──────────────────────────────┼──────────────────────────────┐
          ▼                              ▼                              ▼
┌───────────────────┐          ┌───────────────────┐          ┌───────────────────┐
│  UPPER LIP PTOSIS │          │   ALAR DESCENT    │          │  LOWER EYELID     │
│  (SMILE ASYMMETRY)│          │ (NOSTRIL COLLAPSE)│          │  WEAKNESS / TEARS │
└─────────┬─────────┘          └─────────┬─────────┘          └─────────┬─────────┘
          │                              │                              │
          ▼                              ▼                              ▼
• Mechanism: Toxin diffuses    • Mechanism: Weakening of      • Mechanism: Toxin spreads
  laterally into LLSAN or        dilator naris / alar fibers.   superiorly to orbicularis.
  levator labii superioris.    • Sign: Inability to flare     • Sign: Ectropion, scleral
• Sign: Inability to lift upper  nostril; nasal airway          show, epiphora (tearing),
  lip on smiling; flat smile.    restriction during exercise.   dry eyes.

1. Upper Lip Ptosis & Crooked Smile (LLSAN / LLS Diffusion)

The most common and distressing complication of bunny-line Botox is upper lip drop (ptosis) or smile asymmetry.

• Anatomical Cause: If the injection is placed too far laterally or injected with excessive volume, toxin diffuses into the main belly of the levator labii superioris or the lateral slip of the LLSAN.
• Clinical Presentation: When smiling, the patient cannot elevate their upper lip on the affected side. The smile appears flat, frozen, or noticeably crooked. In severe cases, the upper lip covers the upper teeth during speech.
• Duration: Because nerve terminals must regenerate, lip asymmetry persists for weeks to a few months, gradually improving as the neuromodulator wears off.

2. Nasal Alar Descent & Impaired Nostril Flaring

• Anatomical Cause: Inadvertent downward diffusion into the dilator naris (alar part of the nasalis).
• Clinical Presentation: The nasal ala droops slightly at rest, and the patient loses the ability to voluntarily flare the nostrils. For athletes or individuals with pre-existing internal nasal valve collapse, this can cause mild dynamic nasal obstruction during heavy exercise.

3. Lower Eyelid Weakness & Epiphora (Watery Eyes)

• Anatomical Cause: Toxin placed too high or too close to the medial canthus diffuses into the palpebral portion of the orbicularis oculi or the Horner's muscle supporting the lacrimal sac.
• Clinical Presentation: Weakness of the lower eyelid margin, leading to incomplete blink closure, mild scleral show (lower lid sagging), and epiphora (tearing caused by impairment of the lacrimal drainage pump).

4. Vascular Bruising & Hematoma (The Angular Artery)

The angular artery (the terminal branch of the facial artery) ascends along the lateral side of the nose toward the inner canthus, running alongside the angular vein in the subcutaneous and fascial planes. A deep or wandering needle can pierce the angular vessels, producing immediate swelling and a prominent perinasal hematoma.

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The Glabellar Connection: Compensatory Bunny Lines

One of the most fascinating phenomena in facial aesthetics is the patient who never had bunny lines—until after they received Botox for their frown lines.

                    ┌─────────────────────────────────────────┐
                    │      THE "FROWN SHIFT" MECHANISM        │
                    └────────────────────┬────────────────────┘
                                         │
                                         ▼
                      ┌─────────────────────────────────────┐
                      │ Glabella Treated with Neurotoxin    │
                      │ (Corrugators & Procerus Paralyzed)  │
                      └──────────────────┬──────────────────┘
                                         │
                                         ▼
                      ┌─────────────────────────────────────┐
                      │ Patient Attempts to Frown or Squint │
                      │ (Central nervous system fires motor) │
                      └──────────────────┬──────────────────┘
                                         │
                                         ▼
                      ┌─────────────────────────────────────┐
                      │ Adjacent Nasal Muscles Recruited    │
                      │ (Hyperactive Transverse Nasalis)    │
                      └──────────────────┬──────────────────┘
                                         │
                                         ▼
                      ┌─────────────────────────────────────┐
                      │ NEW DYNAMIC BUNNY LINES APPEAR      │
                      │ (Compensatory Muscle Overactivity)  │
                      └─────────────────────────────────────┘

The "Frown Shift" Mechanism

The human brain does not think in terms of individual isolated muscles; it thinks in terms of facial emotional expressions. When you feel frustration, confusion, or glare into the sun, your motor cortex sends a signal to contract the entire upper facial complex.

If your central frown muscles (the corrugator supercilii and procerus) are completely paralyzed by 20 units of Botox:

1. The neural drive to express that emotion still fires.
2. The motor impulses overflow to the nearest active synergistic muscles: the transverse nasalis and the LLSAN.
3. Because the nose muscles are now doing the work of the entire brow complex, they contract with exaggerated force, newly creating or dramatically worsening bunny lines.

How Expert Injectors Manage the Upper Face

Experienced injectors evaluate the upper face as a unified dynamic system. Rather than completely freezing the glabella in isolation, they assess whether a patient is a "nasal compensator" during initial animation. In patients with strong nasal recruitment, adding a small nasalis dose (typically a few units) in the same session can blunt compensatory overactivity before it becomes established.

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Units, Longevity, and Procedure Cost

Because the nasalis is a small, thin muscle, treating bunny lines requires significantly fewer units than larger areas like the forehead or masseter.

Realistic Unit Dosing Ranges

Note: Dosing must always be customized to individual anatomy, gender, muscle mass, and baseline animation strength. Follow your licensed injector's clinical assessment.

The 2026 paper's per-point doses, expressed in onabotulinumtoxinA (Botox) equivalent units:

With one to two points per side, a typical session lands at 4 to 8 Botox-equivalent units total (2 to 4 per side). Two caveats belong next to that number. First, the paper illustrates its protocol with a Korean toxin product (JETEMA THE TOXIN); the doses are anatomy-guided starting points, not a validated dose-response study. Second, toxin units are not interchangeable across brands — Dysport is commonly converted at roughly 2.5 to 3 Speywood units per Botox-equivalent unit, but conversion ratios are approximations, and each product must be dosed on its own terms (see our neurotoxin brand comparison).

Procedure Pricing Models

Medical practices generally price bunny-line toxin in one of two ways:

1. Per-Unit Pricing: At typical US rates of $12 to $20 per unit of Botox, a 6-unit treatment costs between $72 and $120.
2. Add-On / Tiered Area Pricing: Many practices price bunny lines as a minor "add-on zone" (typically $50 to $100) when performed alongside major areas like the glabella, forehead, or crow's feet. If treated as a standalone appointment, minimum clinic fees (typically $150 to $250) may apply to cover clinical overhead.

Clinical Longevity

No nasalis-specific duration study exists — zero controlled trials have examined this area at all. What the labels establish for the approved facial areas is a duration window of roughly 3 to 4 months, and bunny-line toxin is typically refreshed on the same quarterly schedule as glabellar treatment. Some injectors report that very small total doses in constantly active muscles seem to wear off toward the early end of that window, but that is clinical impression, not measured data — worth asking your injector how they time retreatment. For broader context on choosing between brand formulations, explore our guide to types of FDA-approved Botox.

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When Botox Is the Wrong Solution: Candidacy & Alternatives

Before booking a treatment, verify whether your nasal lines are truly muscular dynamic wrinkles or structural surface changes.

┌─────────────────────────────────────────────────────────────────────────────┐
│                    BUNNY LINE CANDIDACY & DIFFERENTIAL                      │
├──────────────────────────────────────┬──────────────────────────────────────┤
│ BOTOX IS THE RIGHT TOOL              │ BOTOX IS THE WRONG TOOL              │
├──────────────────────────────────────┼──────────────────────────────────────┤
│ • Lines appear only during smiling,  │ • Lines are deeply etched into skin  │
│   scrunching, or squinting.          │   when face is completely at rest.   │
│ • Skin on nose is completely smooth  │ • Wrinkles caused by severe chronic  │
│   when face is relaxed at rest.      │   sun damage and dermal elastosis.   │
│ • Compensatory lines unmasked after  │ • Patient had recent rhinoplasty     │
│   glabellar / forehead toxin.        │   with persistent surgical edema.    │
│ • Goal: Soften dynamic animation.    │ • Goal: Remove deep static grooves.  │
└──────────────────────────────────────┴──────────────────────────────────────┘

• Dynamic Lines (Toxin Indicated): The nose is smooth at rest; wrinkles appear only during dynamic movement. Botox is highly effective.
• Deep Static Creases (Laser / Skincare Indicated): If cross-hatched lines remain clearly visible even when your face is completely relaxed, the dermis has lost its collagen matrix due to chronic photoaging. Relaxing the muscle will soften the movement, but erasing the static groove requires fractional laser resurfacing (CO2 or Erbium), superficial chemical peels, or daily prescription topical retinoids.
• Post-Rhinoplasty Considerations: Patients who have undergone cosmetic or functional rhinoplasty have altered soft-tissue envelopes, subcutaneous scar tissue, and redistributed lymphatic drainage. Neurotoxin should be avoided during the first 6 to 12 months of surgical recovery to avoid disrupting healing tissue planes.
• Nose Volume vs. Muscle (Fillers): If your concern is a dorsal hump, a scooped bridge, or a drooping nasal tip rather than dynamic wrinkles, neuromodulators cannot help. Structural contour changes belong to non-surgical rhinoplasty using hyaluronic acid fillers—a procedure that carries substantial vascular risks detailed in our guide to non-surgical rhinoplasty filler risks.

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Frequently Asked Questions (FAQ)

How many units of Botox do bunny lines usually need?

Most patients require 4 to 8 total Botox-equivalent units, divided between both sides of the nose (typically 2 to 4 units per side). Dysport doses are not interchangeable — injectors commonly use roughly 2.5 to 3 Speywood units per Botox-equivalent unit. Because the nasalis is a small, superficial muscle, conservative micro-dosing delivers optimal smoothing while protecting your smile.

Can bunny line Botox mess up my smile?

Yes, if injected incorrectly or with excessive dose. If toxin is placed too far laterally or diffuses into the levator labii superioris alaeque nasi (LLSAN) or levator labii superioris, it will weaken your upper lip elevators. This causes upper lip ptosis (inability to lift the lip when smiling), leading to an asymmetrical, flattened, or unnatural smile that gradually resolves over weeks to a few months as the toxin wears off.

Do bunny lines go away permanently after Botox?

No. Botulinum toxin is a temporary treatment. As your motor neurons sprout new axon terminals over the following months, muscle function gradually returns, and dynamic bunny lines will reappear during facial animation. Maintaining smooth skin requires repeat treatments roughly every 3 to 4 months.

Does injecting Botox in the nose hurt?

Discomfort is minimal and lasts only a few seconds. Injections on the nasal sidewall feel like tiny pinpricks. Most providers apply a topical compounded numbing cream or an ice pack immediately before injection to numb the skin.

Can I combine bunny line Botox with other treatments?

Yes. Bunny line toxin is most frequently performed in combination with glabellar ("11" lines) and crow's feet injections to achieve harmonious, balanced upper-face rejuvenation. To understand how neurotoxin indications compare across the lower and upper face, see our companion articles on pebble chin mentalis Botox and crow's feet Botox.

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Sources

1. Yi KH, Kim SB. Where Should We Inject Botulinum Toxin for the Bunny Lines? J Cosmet Dermatol. 2026;25(1):e70673. PubMed Central
2. Ahn H, Hu H, Kim SB, et al. Anatomical etiology of bunny lines based on cadaveric dissection and ultrasonographic evaluation. Clin Anat. 2025;38(6):686-691. PubMed
3. Carruthers JDA, Glogau RG, Blitzer A; Facial Aesthetics Consensus Group Faculty. Advances in facial rejuvenation: botulinum toxin type A, hyaluronic acid dermal fillers, and combination therapies—consensus recommendations. Plast Reconstr Surg. 2008;121(5 Suppl):5S-30S. PubMed
4. U.S. Food and Drug Administration (FDA). Botox Cosmetic (onabotulinumtoxinA) Prescribing Information. DailyMed
5. U.S. Food and Drug Administration (FDA). Aesthetic Cosmetic Devices and Procedures Information Hub. FDA Aesthetic Cosmetic Devices