Bunny lines Botox overdone: why, how long and what to do

"Bunny lines" are the small oblique lines that appear on the upper nose when you scrunch it, laugh or squint. They can be softened with small injections of botulinum toxin. Sometimes the effect spills beyond its target: the upper lip lifts less, the smile looks different, or the middle of the face feels "frozen". This is one of the nose problems after an injection. The spillover is bothersome but temporary. Here are the answers to the seven questions people ask most often.

Why can the effect be overdone?

The lines of the upper nose are mainly caused by the nasalis muscle, which wrinkles the skin when you scrunch your nose². But a global consensus on botulinum toxin points out that a neighbouring muscle, the one that lifts the upper lip and the side of the nostril, often plays a major role¹. An anatomical study showed that beneath these lines lies a small area with no muscle, bordered by four different muscles: the procerus between the eyebrows, the nasalis, the muscle that closes the eye and this lip-lifting muscle². The area is therefore narrow and crowded.

Two situations can give the impression of an overdone effect:

• the toxin reaches the lip-lifting muscle: a review of nasal aesthetics describes, when the toxin spreads to the muscles that lift the upper lip, asymmetry, flattening of the groove between the nose and the lip, and a drooping upper lip³. It also notes that injecting this lifting muscle can lengthen the upper lip³;
• a stronger effect than intended: the toxin relaxes the targeted muscles more than desired. No study quantifies this risk for the nose; for the lower face, a review of 35 studies reports lip asymmetry and imbalance⁴.

Treating nose lines is not an indication in the French product labels, which provide in aesthetic use only for frown lines and, depending on the product, crow’s feet and the forehead⁵: it is an off-label use.

How soon after the injection does it appear?

It appears as the effect of the toxin builds up. Side effects are usually seen in the first few days after the injection⁵, within the first week according to the US label of a type A toxin⁶. No source gives a timeframe specific to the nose.

How long does it last?

It lasts at most as long as the effect of the toxin on the muscle affected. The labels give no duration for the nose, which is not an approved indication; for approved areas, the effect of a type A toxin has been shown for up to 4 months⁵. In the studies of nasal injections gathered by a systematic review, effects lasted 2–5 months for the nasal tip and 3–4 months for the sides of the nose³. The details are on the page about how long botulinum toxin lasts.

Is it reversible?

Yes. The effect of the toxin is temporary: transmission between nerve and muscle is gradually restored, first through small nerve sprouts, then by the return of the original nerve ending⁷. In the review of 35 studies, the lip imbalances linked to treatment all resolved on their own⁴.

Is there a treatment?

No product reverses the effect of the toxin: in most cases you have to wait for the lip to regain its movement. If a marked asymmetry develops, the doctor may discuss an adjustment, but no study has assessed a correction specific to this situation. No massage or exercise has shown any effect in the sources we consulted.

What should you avoid?

• Do not ask for another injection to "lift" the lip: adding toxin to the area relaxes the muscles further, and weakness can be made worse by another toxin injected before the effect of the previous one has worn off⁶.
• Do not massage the area in the hours after the injection to "spread" the product.
• Do not judge the result before the effect has fully built up.

When should you see a doctor?

Talk to the doctor who performed the injection if your upper lip gets in the way of eating, drinking or speaking, if the asymmetry is marked, or if it does not improve. Write down the date of the injection and the day the problem appeared; dated photos will help track how it evolves. Difficulty swallowing, a changed voice, difficulty breathing or a problem with your vision are warning signs: call emergency services (15 or 112 in France, or your local emergency number).

If it is rather the tip of your nose that seems lower, see the page on the drooping nose tip after an injection. If your upper lip covers more of your teeth when you smile, the page on the overcorrected gummy smile describes a similar mechanism. In a review of studies on the mid and lower face, including nose lines, no serious side effect was reported⁸.