Thin Upper Lip but Don’t Want More Volume? What to Know About a Lip Flip in 2026

In a March 2025 RealSelf post, a reviewer described her upper lip curling inward and looking thinner when she smiled. This is one person’s account, not clinical evidence.

That concern raises a useful distinction: wanting more of the existing upper lip to remain visible is different from wanting additional lip volume.

That difference sounds small, but it changes the whole conversation about treatment.

Many people assume that a thin-looking lip automatically needs filler. Sometimes that is true. In other cases, the lip already has enough tissue, but muscle movement pulls part of it inward during a smile. A lip flip approaches that second problem differently because it changes how the upper lip moves rather than filling it with extra volume.

That distinction is becoming increasingly relevant in Belgium as aesthetic preferences move toward smaller, less obvious changes. Belgian doctors interviewed in 2025 described patients becoming more interested in treatments that work with their natural features rather than dramatically changing them.

Why Can an Upper Lip Look Much Thinner When You Smile?

Your lips are not static. They change shape every time you talk, smile, drink or make a facial expression.

One of the main muscles involved is the orbicularis oris, a circular muscle surrounding the mouth. It helps close and shape the lips.

When you smile, several facial muscles work together. In some people, the upper lip rolls inward as the muscles around the mouth contract. This reduces the amount of pink lip tissue that remains visible.

That is why a woman can have a reasonably visible upper lip while resting and then appear to have a much thinner one in photographs taken while she is smiling.

This is different from simply having naturally low lip volume.

You can get a basic idea by looking at your upper lip in a mirror while your face is relaxed. Then smile normally. If a large part of the pink upper lip seems to disappear, movement may be contributing to the concern.

A proper medical assessment is still needed because facial anatomy is more complicated than a mirror test, but understanding this difference can help you explain what actually bothers you.

What Does a Lip Flip Actually Do?

A lip flip uses a small amount of botulinum toxin type A around selected parts of the upper lip.

The aim is to temporarily reduce the activity of specific fibres of the orbicularis oris. When the pull of the muscle becomes weaker, the upper lip can turn slightly outward and expose more of its natural surface.

No filler is added to create that effect.

This is not just a theoretical difference. A 2026 prospective study published in Aesthetic Plastic Surgery measured what happened after 17 women received a standardised upper-lip treatment using 4 units of onabotulinumtoxinA.

Researchers used three-dimensional imaging to examine the lips before and after treatment. At 15 days, upper-lip height had increased significantly, but there was no measurable increase in lip volume.

This was a small exploratory study without a comparison group, and it did not assess smiling or other dynamic lip movements. The measured upper-lip height difference was no longer statistically significant at 30 days, so the findings do not establish how much, or for how long, an individual person’s smile will change.

That finding explains the treatment particularly well.

The lip can become more visible without becoming physically larger.

For someone who says, "I want to see more of my upper lip, but I do not want bigger lips," that difference matters.

Why Does a Lip Flip Fit Current Belgian Aesthetic Preferences?

There is no reliable Belgian national database showing exactly how many women receive lip flips each year. Claims giving precise Belgian lip-flip percentages should therefore be treated carefully unless they can be traced to proper data.

What we can verify is a broader change in attitudes toward aesthetic treatments.

In August 2025, ELLE Belgium spoke with Belgium-based plastic surgeon Dr Karl Waked about the direction cosmetic injections were taking. He described patients moving away from dramatic transformations and asking for work that blends naturally with their existing appearance.

A second ELLE Belgium report from December 2025 described a similar preference for natural results, personalised treatment and techniques that respect a person's own anatomy.

The wider demand for injectables is also significant. During a January 2025 meeting of the Flemish Parliament, MP Toon Vandeurzen referred to reports that demand for Botox and filler treatments in Flanders had increased by around 40% in recent years. The parliamentary record confirms that he cited this figure, although it does not identify the original dataset behind it. It should therefore be treated as reported context rather than an official Belgian national statistic.

Together, these trends help explain why a treatment based on a small change in movement can attract attention from women who are uncomfortable with obvious added volume.

Thin Upper Lip or Lack of Lip Volume? The Difference Matters

Two women can both say, "My upper lip is too thin," while having completely different reasons for saying it.

One woman may have very little upper-lip tissue even when her face is relaxed. If she wants significantly fuller lips, changing muscle movement alone may not give her the result she expects.

Another woman may have enough natural lip tissue at rest, but much of it becomes hidden when she smiles. Her problem is partly related to movement.

This is why treatment should begin with the concern rather than the product.

Instead of simply saying that you want bigger lips, it can be more useful to explain exactly what happens.

For example:

"My upper lip looks fine when I am relaxed, but it disappears when I smile. I want more of it to show, but I do not want noticeably larger lips."

That gives a medical professional much more useful information.

Lip Flip vs Lip Filler: Which One Actually Adds Volume?

Lip filler and a lip flip can both make an upper lip look more noticeable, but they do it in different ways.

Hyaluronic acid fillers add injectable material to the lips. They can increase physical volume, support certain areas, improve definition or alter proportions.

A lip flip works through temporary muscle relaxation.

The 2025 systematic review published in Archives of Dermatological Research explains that botulinum toxin is used to create upper-lip eversion and improve contour without adding volume. The researchers initially identified 48 papers, but only seven studies provided suitable information about injection sites and dosages. Commonly reported techniques involved approximately 4 to 6 units of botulinum toxin type A.

That relatively small evidence base is worth understanding because social media can make the procedure seem more established and standardised than the research actually is.

A simple way to separate the two options is to think about the desired change.

If you want more physical lip tissue, filler may be worth discussing. If your main concern is that your existing upper lip rolls inward during smiling, a lip flip may be more relevant to explore with a qualified medical professional.

Neither option is automatically better. They are designed to solve different problems.

Why Interest in Subtle Injectable Treatments Is Not Just a Social Media Trend

The broader numbers show how established non-surgical aesthetic treatments have become.

According to the International Society of Aesthetic Plastic Surgery, or ISAPS, close to 38 million aesthetic procedures were performed worldwide in 2024.

More than 20.5 million were non-surgical procedures. Botulinum toxin was the world's most common non-surgical cosmetic treatment, with around 7.8 million procedures performed by plastic surgeons.

People aged 35 to 50 accounted for 47% of botulinum toxin procedures.

These are worldwide figures and should not be presented as Belgian lip-flip numbers.

They do show that treatments based on temporary muscle relaxation are already a major part of aesthetic medicine.

The more interesting change in Belgium is not simply that people want injectables. It is that some people appear to want less obvious results from them. That fits the specific appeal of a lip flip because its purpose is not to create dramatic additional volume.

What Real Patients Notice That Photos Do Not Show

A before-and-after photograph tells you what somebody's lips look like. It does not tell you what their mouth feels like.

That difference matters.

The orbicularis oris helps with everyday actions such as drinking, eating, speaking, kissing, whistling and pursing the lips. Temporarily relaxing part of that muscle can therefore affect function as well as appearance.

Real patient discussions often mention this.

Some people report being pleased that more of their upper lip remains visible when smiling. Others describe temporarily finding it strange to drink through a straw, sip from a cup or purse their lips.

Individual online experiences cannot predict your result, and they should never be treated as clinical evidence. They are still useful because they highlight practical details that a polished before-and-after image cannot show.

The scientific research supports the possibility of these temporary effects. The 2026 Aesthetic Plastic Surgery study reported mild and transient adverse events that included numbness and temporary functional limitations. In that study, the reported effects were resolved within 30 days.

The 2025 systematic review similarly found that reported problems were generally mild and temporary.

A Small Cosmetic Change Still Deserves a Proper Medical Discussion

A lip flip may sound minor because only a small quantity of botulinum toxin is normally used.

The location makes precision important.

The mouth is constantly moving, so relaxing too much muscle or treating an unsuitable area can affect normal function.

That is one reason the Belgian trend toward subtle treatment should not be confused with casual treatment.

The same ELLE Belgium interview that discussed less visible cosmetic work also stressed the importance of detailed anatomical knowledge, correct placement and appropriate dosing.

A natural-looking result does not mean the procedure requires less medical judgement.

In fact, when the desired difference is small, careful assessment becomes even more important.

How Quickly Does a Lip Flip Work?

The final appearance is not immediate.

Botulinum toxin takes time to affect muscle activity, so the lip normally changes gradually over the following days.

The 2026 clinical study measured significant changes at 15 days, which is a useful reminder not to judge the result after one or two days.

If your main concern is an upper lip that disappears when smiling, compare photographs taken in similar lighting while making the same expression.

A relaxed photograph may show very little difference because the reason for treatment was related to movement in the first place.

How Long Does the Effect Last?

The effect is temporary.

How long it remains noticeable varies because people differ in muscle activity, anatomy, metabolism, treatment technique and dose.

This temporary nature can be attractive to someone who has spent hours of research looking at lip filler transformations but still feels uncomfortable with the idea of adding volume.

However, temporary does not mean immediately reversible.

If you do not like the way the muscle feels after treatment, the botulinum toxin cannot simply be removed in the way certain hyaluronic acid fillers may be dissolved. You normally have to wait while muscle activity gradually returns.

That is an important part of the decision and should be understood before treatment rather than afterward.

Can a Lip Flip Fix a Gummy Smile Too?

Sometimes botulinum toxin is used when too much gum shows while smiling, but a gummy smile and a thin upper lip are not automatically the same issue.

Excessive gum display can be influenced by several factors, including facial muscle movement, gum anatomy, tooth position and jaw structure.

This means the right approach depends on why the gums are visible.

If gum display is your main concern, explain that specifically during your assessment rather than assuming a standard lip flip will correct it.

The goal should always be to identify the cause before selecting the treatment.

Who Is Most Likely to Consider a Lip Flip?

A lip flip is most relevant to discuss when someone wants a small change in upper-lip position rather than a major increase in lip size.

It may be worth asking about if your upper lip looks acceptable at rest but becomes much thinner when you smile, or if you want more of your existing lip to show without adding obvious volume.

It may be less suitable if your main concern is genuinely low lip volume and you want a noticeable increase in size.

The treatment also should not be chosen simply because it appears subtle or because someone else's result looks good.

Faces move differently.

A dose and placement that works well for one person may not produce the same result for another.

FAQs About Lip Flips for Thin Upper Lips

Does a lip flip make your lips physically bigger?

Current evidence suggests that it does not create true lip volume. The 2026 Aesthetic Plastic Surgery study found increased upper-lip height but no measurable increase in lip volume after treatment. The lip can therefore look more visible without becoming physically larger.

Is a lip flip better than lip filler for a thin upper lip?

Neither treatment is universally better. If your lip lacks actual volume, filler may better match that goal. If enough natural lip is present but it curls inward when you smile, changing muscle movement may be more relevant. A medical assessment can help distinguish between those problems.

Will a lip flip look natural?

The goal is usually a subtle change because the treatment exposes more of the existing upper lip instead of adding material. The final appearance still depends on anatomy, injection placement, dose and the strength of the surrounding muscles.

Can a lip flip affect drinking or speaking?

It can. The treated muscle contributes to mouth movement, so temporary changes in drinking, pursing the lips or other oral movements can occur. The available research generally describes these effects as mild and temporary, but they should still be discussed before treatment.

Want More of Your Upper Lip to Show Without Making It Bigger?

The most useful question is not whether lip flips or fillers are more popular in 2026.

The better question is what you actually want to change.

If your upper lip is thin because it lacks physical volume, relaxing a muscle cannot create the same result as adding volume.

If your upper lip is visible while your face is relaxed but rolls inward when you smile, the issue may be partly related to movement. In that situation, the goal may not be to make your lips bigger at all. You may simply want more of your natural lip to remain visible.

The latest evidence makes that distinction clearer than before. The 2026 Aesthetic Plastic Surgery research objectively found increased upper-lip height without increased lip volume, while Belgian aesthetic reporting shows a broader preference for subtle treatments that respect existing facial anatomy.

A lip flip is still a medical treatment. Results vary, the effect is temporary, and normal lip movement can be affected for a short time.

For someone who keeps looking at her smile and thinking, "I do not want bigger lips. I just wish my upper lip did not disappear," understanding that difference is a much better place to start than choosing a treatment based on a trend.