Drooping lip after toxin: lip ptosis and lip incompetence
Quick facts
- Definition
- Drooping or weakness of the lip after botulinum toxin, due to an effect on a muscle that was not the target or an effect greater than intended.
- Signs
- Upper lip lower when smiling, lower lip that does not move down, difficulty sealing the lips, using a straw or pronouncing p, b and m.
- Most cited muscles
- Zygomatic muscles and lip elevators, orbicularis oris, depressor labii inferioris and mentalis.
- Duration
- Temporary: usually improves as the toxin's effect wears off, over weeks to a few months.
- Relevance in facial harmonization
- Known complication of treatments to the midface and lower face, which should be listed in the consent form.
A drooping lip after toxin is the sagging, asymmetry or weakness of the upper or lower lip after an application of botulinum toxin. It happens when the product reaches a muscle that was not the target, through spread or positioning, or when the effect on the treated muscle is greater than planned. When the strength of the orbicularis oris drops to the point of making it hard to close the lips, it is called lip incompetence. It is a temporary complication.
Which muscles are usually involved?
| Affected muscle | Treatment usually behind it | How it appears |
|---|---|---|
| Zygomaticus major and minor | Crow's feet injected low, cheekbone area | Upper lip and corner lower when smiling, on one side |
| Upper lip elevators | Gummy smile with an effect greater than intended | Lengthened upper lip, flattened smile |
| Orbicularis oris | Perioral lines (lip lines) | Difficulty sealing, liquid leaking, altered speech |
| Depressor labii inferioris | Spread from the depressor anguli oris | Lower lip that does not move down on one side in a broad smile |
| Mentalis | Chin toxin with an effect greater than intended | Less firm lower lip, difficulty projecting the lip |
The difference between an effect from the target muscle and from a neighboring one helps plan the next sessions. Smile changes without an evident droop are covered in asymmetric smile after toxin.
How long does it last?
The effect is temporary and follows the action of the toxin: strength usually returns gradually, over weeks to a few months, and the time varies with the dose, the muscle and the person. There is no antidote that reverses toxin already bound to the nerve. The approach is to assess, record with photo and video, advise and follow up. In some cases, the professional considers adjustments to balance symmetry, at their discretion and after assessment.
How to prevent it and how does it appear in the assessment?
- Assessment beforehand: record the smile, speech and lip symmetry in photo and a short video. Prior asymmetry is common and changes how the aftermath is read.
- Muscle map: knowing each patient's anatomy reduces the risk of spread. The overview is in the muscle map for botulinum toxin.
- Consent: the possibility of changes in the smile and speech should be in the form, with the information that it is temporary.
- Professions that depend on the mouth: wind instrument players, singers and people who speak a lot in public need a specific conversation about the perioral area.
The broader topic is covered in complications with botulinum toxin and ptosis after botulinum toxin.
Also called: lip ptosis after toxin, lip incompetence after toxin, weak lip after botox.
Frequently asked questions
Does a drooping lip after botox go back to normal?
Generally yes. The toxin's effect is temporary, and strength returns gradually as the action wears off, which usually takes weeks to a few months. The professional should assess, record and follow up until it improves.
What is lip incompetence after toxin?
It is difficulty closing and sealing the lips properly when the orbicularis oris or neighboring muscles are weakened. It shows up as liquid leaking when drinking, trouble with a straw, whistling and sounds such as p, b and m.