In short. A lip flip and a gummy smile can share one cause: the muscle that lifts the upper lip. What relaxing it changes, what it does not, and when surgery is the finding.
Key points
- Relaxing the muscle that lifts the upper lip wears off completely.
- That makes it a reasonable way to see whether a lower lip position suits your face before considering anything that removes tissue and stays.
Two complaints that look unrelated often share a cause. A lip that seems to disappear when you smile, and a smile that shows a great deal of gum, can both be the work of the muscle that lifts the upper lip.
What the muscle does
The muscle that raises the upper lip runs from the cheekbone down into the lip, and it is what pulls the lip upwards when you smile. Where it acts strongly, the upper lip rolls inwards and upwards, so the vermilion turns under and the gum shows. At rest it holds the lip slightly higher than it would otherwise sit. Relaxing it lets the lip come down, which is why the vermilion shows more at rest and less gum appears when it moves.
The lip flip, described without the name
What is called a flip is not a repositioning of the lip. It is the effect of relaxing that muscle, seen from the front: the upper lip settles lower, so more of the coloured part is visible without anything being added. It reaches a finding of position only. It adds no tissue, so it does not answer a complaint about thin lips, and it does not change the length of the skin above the lip. Its advantage is that it wears off.
The gummy smile, and its four causes
A smile that shows a lot of gum can come from the muscle lifting the lip too far, from a short upper lip, from teeth that are small relative to the mouth, or from a long upper jaw. Only the first is treated by relaxing muscle. Where the lip is short, the finding is tissue or length, and where the jaw is long, the finding is skeletal and belongs to a jaw assessment. An injectable used on the wrong one of the four produces no visible change and delays the right answer.
Where the surgical route comes in
Where the finding is the length of the skin above the lip, the route that changes it removes a strip of skin and lifts the border, which is not reversible. Where the finding is the jaw or the teeth, the route is orthodontic or surgical and is planned by those specialists. Where the finding is the muscle, relaxing is the reversible option and an operation is not the alternative to it, because the two do not act on the same thing.
The most reversible option on this site
Relaxing the muscle that lifts the upper lip wears off completely. That makes it a reasonable way to see whether a lower lip position suits your face before considering anything that removes tissue and stays.
Findings that are not muscle findings
- A smile that shows gum because the upper jaw is long, which is a jaw assessment.
- A lip that has become short or tight on one side only, or that will not move.
- Sudden weakness of one side of the face, which needs emergency assessment.
Frequently asked questions
How long does relaxing the upper lip last, and what happens when it wears off?
The effect appears over several days and wears off over weeks to a few months, depending on the person and on how much was used. It fades rather than stopping, so the lip drifts back to where it started rather than changing suddenly. Because the effect is temporary, repeating it is a decision taken each time rather than a commitment made once, which is the main reason this route is often the first one discussed for a lip that sits high.
Can relaxing the muscle affect how I speak or drink?
It can, and the effect is usually small and temporary. The muscle that lifts the upper lip also helps shape certain sounds and helps keep liquid inside the mouth while drinking, so a strong effect can make some words less crisp or make drinking from an open cup slightly awkward for a few weeks. This is a reason to start with less rather than more, and to say so at the follow-up rather than accepting it.
Is a gummy smile always a muscle problem?
No, and treating it as one is why some people are disappointed. A smile can show a lot of gum because the muscle lifts the lip too far, because the upper lip itself is short, because the teeth are small relative to the mouth, or because the upper jaw is long. Only the first is a muscle finding. The others belong to a dental or jaw assessment, and an injectable used on them adds nothing.
Risks & Limitations
- A dissolvable gel filler can be broken down with an enzyme. Skin or tissue removed by an operation cannot be put back.
- Bruising and swelling after a lip injection are common and usually settle over one to two weeks.
- Repeated filler over years can accumulate in the lip, and dissolving may not return it to its untreated state.
- Every operation on the lip leaves a scar, and the lines above the border and the way the mouth closes can change.
When to Seek Care
- Severe pain, blanching or mottled skin during or after a lip injection, or a change in vision.
- A sore, ulcer or white patch on the lip that has not healed in a few weeks.
- A lip that is numb, or a mouth that no longer closes, after an operation.
- Fever with spreading redness, warmth or discharge, or a wound that opens.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
- National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
- Cochrane Library — systematic reviews
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.