Key facts
- What they are
- Diagonal creases on the sides of the upper nose, seen on scrunching, laughing or squinting
- The muscles
- The nasalis mainly, with the procerus, the orbicularis oculi and the lip and nostril elevator pulling on the thin skin between them
- Why they appear after frown treatment
- When the glabella is relaxed, some people recruit the nose instead, and lines that were always there become noticeable
- Dynamic or static
- Most bunny lines are dynamic; etched lines at rest are less common and need skin-directed care
- Treatment
- Small, precisely placed doses of botulinum toxin into the nasalis, away from the lip elevator and the angular vein
- Who assesses
- Dr Sin Yong examines the nose in motion and decides whether treatment is wanted at all
What causes bunny lines?
Bunny lines are caused by the nasalis muscle. Its transverse part drapes across the upper part of the nose, and when it contracts it compresses the nasal sidewalls and wrinkles the overlying skin into short diagonal creases, usually angled from the inner corner of the eye down toward the nose. The muscle is recruited when you scrunch the nose, in a wide laugh, in a squint against glare, and in some people in ordinary speech. A cadaveric and ultrasound study of the region in 2025 found that the skin where bunny lines form sits over a small muscle-free triangle bounded by the procerus, the nasalis, the orbicularis oculi and the levator labii superioris alaeque nasi, the small muscle that lifts the upper lip and flares the nostril; the lines are produced by those neighbouring muscles pulling on the thin skin between them, which is why injection points are chosen at the muscle borders rather than into the crease itself.
The lines become more noticeable in two situations. The first is simple repetition on thinning skin, the same story as every expression line. The second is specific to this area: after the frown complex between the brows has been relaxed, some people unconsciously shift the effort of a frown or squint to the nose, and lines that were always faintly present now stand out. They are not caused by the treatment; they are unmasked by it. The botulinum toxin page describes how the upper-face muscles are planned as a group for this reason, and the forehead lines and frown lines guide covers the glabellar complex next door.
What do bunny lines look like, and what are they confused with?
Bunny lines appear as two to several short, oblique creases on the upper sides of the nose, often meeting a faint horizontal crease across the nasal root. They are usually symmetrical, they appear within a fraction of a second of scrunching or laughing, and in most people they disappear completely when the face relaxes. In a smaller group, usually after many years of expression or heavy sun exposure, a trace remains at rest.
They are distinguished from frown lines, which are vertical and sit between the brows, and from the horizontal crease at the root of the nose made by the procerus, which runs straight across rather than diagonally. Lines that run from the side of the nose down onto the cheek in a broad smile belong to the cheek elevators and are a different concern. Flaring of the nostrils on speaking is a separate muscle action again. Each of these is read in motion at assessment, because photographs taken at rest show almost nothing in this area.
“If the line is there at rest, relaxing the muscle will not remove it. The skin has learned the crease — and the skin is what needs treating.”
Dr Sin YongOn the dynamic–static distinction
In what order is treatment planned?
The first question is whether bunny lines need treating at all. Many people find them part of a natural laugh and are relieved to hear nothing is required. Protection comes before any procedure: daily sunscreen and a skin routine the barrier tolerates slow the progression from dynamic to static lines in this area as everywhere else.
Where treatment is wanted, botulinum toxin is the direct answer to a line made by movement. It is a prescription medicine that reduces the nerve signal to the muscle, so the nasalis contracts less and the skin is folded less. Dr Sin Yong places small doses high on each nasal sidewall at the borders of the muscles that pull on the area, away from the lip elevator below and the angular vein beside the nose. Bunny lines are often treated at the same visit as the frown and forehead so that the upper face is balanced as a set, and the dose is conservative because the surrounding muscles affect the smile.
Skin-directed treatment is reserved for lines that remain at rest, which is uncommon here. Where the skin over the nasal bridge has thinned or etched, polynucleotides or a light fractional laser can be considered. Filler is not usually appropriate for bunny lines: the lines are made by movement, the skin is tightly bound to the nose, and the angular vessels run close by.
Lines around the upper nose: bunny lines and their look-alikes| Type or look-alike | How to recognise it | Muscle or cause | What it tends to need |
|---|
| Bunny lines | Short diagonal creases on the upper nasal sidewalls on scrunching or laughing | Nasalis and its neighbours pulling on thin skin | Conservative botulinum toxin high on the sidewall, if treatment is wanted |
| Frown lines (the 11s) | Vertical creases between the brows on frowning | Corrugator and procerus | Botulinum toxin to the glabellar complex |
| Nasal root crease | A single horizontal line across the nasal root | Procerus pulling the brow centre down | Usually treated with the frown complex |
| Cheek smile lines | Lines from the nose down onto the cheek in a broad smile | Cheek elevators and skin quality | Assessment of cheek support and skin; not nasal toxin |
| Etched nasal lines at rest | Creases visible with the face still | Dermal change after years of folding | Skin-directed treatment alongside toxin |
Who it suits and who should wait?
Treatment suits people whose nose creases prominently with every laugh and who would prefer it softened, people who have noticed new nasal lines after frown treatment elsewhere, and people having the upper face treated as a set. It is deferred in pregnancy and breastfeeding, with an active infection or inflamed skin on the nose, with a neuromuscular condition such as myasthenia gravis, a known allergy to a botulinum toxin product, or medicines that affect nerve-to-muscle transmission that have not been reviewed.
People who want the lines treated but whose main concern is a long upper lip or a gummy smile need a different conversation, because the muscles that produce those features sit immediately beside the nasalis, and treating one affects the other. Anyone who has had recent nose filler or a nose thread should say so, since the anatomy and the risk of injecting near a vessel change.
What are the risks, and when should you call?
Small bruises and tenderness at the injection points are the common effects and settle. The specific risk at this site is spread of the medicine into the levator labii superioris alaeque nasi just below, which can lengthen the upper lip, flatten the smile on one side or change how the nostril moves. Because the effect persists for as long as the medicine acts, this cannot be reversed; it fades as the medicine wears off. Conservative doses placed high on the nasal sidewall are how the risk is reduced, and it is never removed entirely.
Call the clinic for a lopsided smile, a lip that feels heavy or will not lift evenly, a drooping eyelid or brow, or double vision. Difficulty swallowing, speaking or breathing after any botulinum toxin injection is an emergency and needs a hospital emergency department. The complication care page explains the steps to take wherever you were treated.
What determines the fee, and when should you see a doctor?
Singapore's rules prevent clinics from advertising prices, so this page gives the factors that set the fee rather than figures. Bunny lines are a small zone, and the fee depends mainly on whether they are treated alone or alongside the frown and forehead, on the dose each side needs, and on the formulation chosen. A written quote is given at consultation, and the fee page explains how quotes are prepared.
See a doctor when nasal creases have appeared or deepened after a frown treatment elsewhere, when the two sides of the nose move differently, or when creasing comes with a new change in the smile or the lip, which needs medical review rather than a cosmetic visit. The consultation process page sets out how the assessment runs, what is examined and what to bring.
