What actually happens

A lip flip is a very small dose of botulinum toxin placed into the muscle that rings the mouth, right at the border of the upper lip. Four to six units is typical. The muscle relaxes, and the lip that was being held slightly rolled inward rolls outward instead.

The result is that more of the pink surface of the lip is visible. Nothing has been added and nothing has been removed. A structure that was pointing one way is now pointing another way, and the visible portion of it increased as a consequence.

That is the entire mechanism, and almost every practical question about the procedure, including who it suits and how long it lasts, follows from it.

It adds no volume, and that is the point people miss

Patients regularly arrive having seen before and after photographs and assume this is a cheaper, needle-light version of filler. It is not a version of filler at all. Filler places material into the lip and the lip becomes larger. A flip places nothing, and the lip stays exactly the size it was.

The confusion is understandable because in the right patient the photographs look similar. In the wrong patient they do not, and the wrong patient is the one whose lip is genuinely thin rather than merely rolled under. Relaxing a muscle cannot supply tissue that is absent. Someone who wants a fuller lip and receives a flip will get a small change in the visible pink and will not get what they came for. If volume is the goal, lip augmentation is the procedure that matches it.

Who it genuinely suits

The best candidate has reasonable lip body but very little pink showing, either at rest or specifically when smiling. A common description is that the upper lip vanishes in photographs. On examination the lip is there, it is simply rotating inward under the pull of the muscle.

It also suits people who want a change small enough that nobody identifies it as a treatment. This is a subtle procedure by nature, and its ceiling is low. That is a limitation when someone wants a dramatic result and an advantage when they do not.

Patients whose main complaint is the distance between the nose and the lip are a different group entirely, and the honest answer to them is that this is not their procedure. That measurement is addressed by a lip lift, which is surgical and permanent.

Why it wears off faster than your other Botox

Patients who have had the forehead or the frown lines treated arrive expecting three to four months and are often surprised to get six to twelve weeks. This is not a product failure and it is not a sign the dose was too small.

Two things are working against duration. The dose is low, because a few units is all this area tolerates before the lip stops behaving normally. And the muscle is in near constant use, since it works during speech, eating, drinking and every expression involving the mouth. A small dose in a heavily used muscle returns to baseline sooner.

The practical consequence is scheduling and budget. Four or five treatments a year is the realistic pattern, not two or three, and anyone comparing the cost of a flip against filler should compare over twelve months rather than per appointment. What to expect in the days afterward is largely the same as any neurotoxin treatment and is covered in Botox aftercare.

The first two weeks

Onset is not immediate. Most people notice a change between day three and day seven, and the full effect is present at around two weeks. Judging the result at day two and concluding it did not work is the most common source of unnecessary follow-up calls.

A small adjustment can be made once the effect has fully developed, and doing it then rather than earlier avoids stacking a second dose onto one that had not finished arriving. Overtreatment here is harder to live with than undertreatment, because the correction for too much is waiting.

Side effects worth hearing about first

The predictable ones come directly from relaxing a muscle you rely on. Drinking through a straw can feel awkward. Whistling may be difficult. Plosive consonants, the P and B sounds, can take more effort, and singers and wind instrument players should think carefully before treating this area at all.

Asymmetry happens and is usually fixable with a small adjustment. The problem that is not quickly fixable is overtreatment, which produces a lip that looks flattened and works poorly, and which has to wear off on its own schedule. That is the main argument for a conservative first dose in a new patient.

Where the gummy smile question fits

A lip flip is frequently mentioned as a treatment for a gummy smile, and it can contribute, but it is usually a supporting part rather than the main one. Excess gum show is mostly produced by the muscles that lift the upper lip, so the treatment that lowers the lip over the gum line is directed at those elevators.

It is also worth knowing that not every gummy smile is muscular. Some are dental and some are skeletal, related to tooth height or the position of the upper jaw. Injecting a muscle that was never the cause produces a small change and a disappointed patient, which is why this is examined rather than assumed. The fuller picture is in gummy smile treatment.

Combining it, and when not to bother

A flip and a small amount of filler together often produce a better result than either pushed to its limit, because they solve different halves of the problem. Increasing show and adding a modest amount of volume is a more natural outcome than overfilling a lip to compensate for a rolling problem that filler was never going to fix.

Equally, there are patients for whom the honest recommendation is to skip it. If the philtrum is long, if the lip is substantially deflated, or if the visible complaint is really about the teeth, this procedure is the wrong tool and saying so is more useful than performing it. How it sits within neurotoxin treatment generally is covered in Botox.

Find out whether this is your procedure

The examination separates a lip that is rolling under from one that has lost volume, and from a philtrum that has lengthened. Those three complaints look similar in a photograph and are treated in three different ways.

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Usually six to twelve weeks, which is noticeably shorter than the three to four months people expect from Botox elsewhere. The reason is dose and workload. The muscle around the mouth is small and receives only a few units, and it is one of the busiest muscles in the body because it works during every word, every meal and every expression. A low dose in a constantly active muscle recovers faster. Patients who budget for it as though it were a glabella treatment are usually surprised, and it is better to know that before the first appointment than after the third.
No, and this is the most common misunderstanding about it. Nothing is added. A few units of botulinum toxin relax the muscle that holds the upper lip rolled slightly inward, and the lip rolls outward instead, so more of the pink surface is visible. The lip has not gained volume, it has changed position. Photographed side by side the effect can resemble a small filler result, which is why the two get confused, but the mechanism is entirely different and so is the person each one suits.
It depends on whether your complaint is volume or show. If the lip has reasonable body but disappears when you smile, or if very little pink is visible at rest, the flip addresses that directly. If the lip is genuinely thin or has lost volume over time, relaxing a muscle will not replace tissue that is not there, and filler is the operation that matches the problem. The two are also combinable, and in patients who want a modest increase in show alongside a small volume change that combination is often better than pushing either one further on its own.
A lip flip is a few units of neurotoxin lasting a couple of months. A surgical lip lift removes a small strip of skin under the nose to permanently shorten a long philtrum, the distance between the nose and the lip. They treat different anatomy. If the space between your nose and your upper lip has lengthened with age and the lip sits low, no amount of muscle relaxation changes that measurement. If the philtrum is a normal length and the lip simply rolls under, the flip is the smaller and more reversible answer.
The predictable ones come from relaxing a muscle you use constantly. Some patients find drinking through a straw awkward for a few weeks, or notice that whistling is harder, or that plosive sounds such as P and B take slightly more effort. Speech changes are usually subtle and settle as the effect wears off. Asymmetry is possible and is usually correctable with a small adjustment. The main avoidable problem is overtreatment, because too many units in this area produce a lip that looks flattened and behaves poorly, and that has to be waited out rather than reversed.
It can contribute, but it is rarely the whole answer on its own. A gummy smile is usually driven by the muscles that pull the upper lip upward, so treating those elevators is the part that lowers the lip over the gum line. The flip is often used alongside that rather than instead of it. How much gum shows, how much your lip elevates, and the height of your upper teeth all change what is achievable, and some gummy smiles are dental or skeletal rather than muscular, in which case injecting is aimed at the wrong structure entirely.

Related reading: lip augmentation when the goal is volume, lip lift when the philtrum has lengthened, Botox for neurotoxin treatment generally, and dermal fillers for how filler behaves across the face.