Lip flip or lip filler: which one do you actually need?
September 2026
Key takeaways
- A lip flip and lip filler do not do the same thing. A lip flip relaxes a muscle; filler adds physical volume.
- A lip flip is most effective when the upper lip disappears on smiling, or when gummy smile is the concern.
- Lip filler is appropriate when the goal is genuine volume, definition, or correction of volume-related asymmetry.
- A lip flip is temporary (typically six to twelve weeks); lip filler typically lasts six to twelve months.
- The two treatments can be combined in the same session, or at separate appointments.
- Neither treatment alone addresses long philtrum, downturned corners, or significant perioral skin laxity.
- The right starting point depends on assessment at consultation, not on which treatment name sounds more appealing.
I see this question in almost every lip consultation: should I get a lip flip or lip filler? The two treatments are often described as alternatives, but that framing misleads people from the start. A lip flip and lip filler do not compete with each other because they do not do the same thing. One relaxes a muscle. The other adds volume to tissue. Which one you need depends entirely on what is causing the concern you want to address, not on which treatment sounds more appealing or less intimidating.
In this article I want to explain precisely what each treatment does, what it cannot do, and how to work out which is the right starting point for your goals. Where clinical evidence exists, I have cited it. Where uncertainty remains, I have said so clearly.
What a lip flip actually does, and what it does not
A lip flip uses a small quantity of botulinum toxin, typically four to six units, injected into the orbicularis orisOrbicularis orisThe circular muscle surrounding the mouth that controls lip movement. The lip flip targets its superficial fibres along the upper lip border., the circular muscle that surrounds the mouth. The injection targets the superficial portion of that muscle along the upper lip border, partially relaxing the fibres that normally pull the upper lip inward and downward when you smile or speak.
When those fibres relax, the upper lip everts slightly. It rolls outward, revealing more of the pink tissue (the vermillionVermillionThe coloured, visible part of the lip - the pink or red surface that defines the lip's boundary with the surrounding skin.) that was previously hidden. The lip looks more visible, and in some people, slightly fuller.
A 2025 systematic review of the available published literature, conducted by Pitchford, Desrosiers and Tolkachjov and published in the Archives of Dermatological Research, identified seven studies meeting inclusion criteria on lip flip technique, injection sites and dosages. The review found that the procedure consistently produced upper lip eversion and improved contour, with high patient satisfaction and minimal downtime. Reported side effects were mild and transient, and included temporary difficulty whistling or drinking through a straw, both of which resolved within weeks as muscle function returned.
A 2026 prospective study by Germani, Munoz-Lora, Roschel, Cotofana and colleagues, published in Aesthetic Plastic Surgery, assessed outcomes in 17 women who received a standardised four-unit dose of onabotulinumtoxinA into the orbicularis oris. Objective measurement by stereophotogrammetry showed a modest but statistically significant increase in upper lip height at 15 days (p = 0.011), with no change in lip volume. Patient-reported satisfaction was high (FACE-Q mean score 79.2 ± 19.9; Global Aesthetic Improvement Scale median score 1). All adverse events were mild and transient, resolving spontaneously within 30 days.
These findings are important to understand clearly. The lip flip enhances lip projection through muscle relaxation, not through adding any material to the lip. The study confirmed what I see clinically: the visual change is real and is consistently perceived by patients, but it is modest. It is a change in how the lip sits, not a change in how much lip tissue exists.
What a lip flip changes:
- How much of the upper lip is visible at rest and when smiling
- Upper lip projection relative to the lower lip
- The appearance of a gummy smile, by reducing how far the upper lip elevates when you smile
- Fine vertical lines above the upper lip (perioral rhytides), modestly
What a lip flip does not change:
- The actual volume or fullness of the lips
- The lower lip
- The shape of the vermillion borderVermillion borderThe boundary between the coloured lip tissue (vermillion) and the surrounding skin. Defining or sharpening this border requires filler, not a lip flip. in any structural sense
- Lip symmetry where the difference is one of volume rather than muscle positioning
- The length of the philtrum (the area between the nose and the upper lip)
How long results last: Published evidence suggests the effect peaks at around 10 to 14 days and that results are temporary, consistent with botulinum toxin pharmacodynamics. Duration in clinical literature varies across reports, with some noting effects beginning to fade by six to eight weeks and others citing up to three months. The oral musculature is highly active, which contributes to faster metabolisation of the toxin at this site compared with other areas such as the forehead.
Temporary functional effects to be aware of: Because the orbicularis oris controls many fine lip movements, partial relaxation can temporarily affect the ability to drink from a straw, whistle, or make sounds requiring tight lip closure. The Germani 2026 study documented these as mild and transient. The Pitchford systematic review notes they resolve within weeks. Patients who play wind instruments, or whose work depends on precise lip control, should discuss this before booking.
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What lip filler actually does, and what it does not
Lip filler uses hyaluronic acid (HA)Hyaluronic acid (HA)A naturally occurring molecule found throughout the body's connective tissue. In lip filler, an HA gel is injected to add volume and hydration. HA fillers can be dissolved with hyaluronidase if needed., a naturally occurring molecule found throughout the body's connective tissue, injected directly into the lip tissue to add volume, structure and hydration. The hyaluronic acid gel binds water and integrates with the surrounding tissue, creating a physical increase in the amount of material present.
The 2025 systematic review and meta-analysis by Wen, Perez Rivera, Wyatt, Lee, Oh, Boyd and Karp, published in the Aesthetic Surgery Journal, examined 16 randomised controlled trials of hyaluronic acid lip fillers. The meta-analysis found that 82% of patients (95% confidence interval: 67 to 92%) showed improvement in aesthetic appearance, and 68% (95% CI: 58 to 78%) reported satisfaction with their outcome. Adverse events were reported in approximately 50% of participants, with the most common being swelling (78%), firmness (48%), bruising (34%) and tenderness (33%), all typically short-lived. Serious adverse events requiring treatment, follow-up or lasting beyond 30 days occurred in approximately 1.5% of cases.
The wide confidence intervals on some of these findings reflect genuine variability across the included trials, in terms of products used, injection technique and patient populations. I read this data as a direction of effect, not as a precise prediction for an individual patient, and I explain that to patients at consultation.
What lip filler changes:
- Actual lip volume, including upper lip, lower lip or both depending on the treatment plan
- The definition and sharpness of the vermillion border
- Lip symmetry where differences are volume-related
- The Cupid's bow definition
- Hydration and surface quality of the lip tissue
- Fine perioral lines around the lip border, to a degree
What lip filler does not change:
- Muscle activity or dynamic lip movement when smiling or speaking
- The position of the lip relative to the nose (philtrum length)
- A gummy smile, which is a muscle-activity issue rather than a volume issue
- The underlying anatomy in any permanent way, since hyaluronic acid fillers are reversible
How long results last: Significantly longer than a lip flip. Published evidence across the HA lip filler literature suggests durations of six to twelve months are typical for most patients, though this varies by product, volume injected, individual metabolism and the area treated.
On reversibility: Hyaluronic acid fillers can be dissolved using hyaluronidase, an enzyme that breaks down the filler material, typically within 24 to 48 hours of injection. This is a meaningful safety advantage that I raise with every patient. A lip flip, by contrast, cannot be manually reversed. If the result is not what you wanted, you wait for the botulinum toxin to wear off naturally.
Lip flip versus lip filler: a direct comparison
| Feature | Lip flip (botulinum toxin) | Lip filler (hyaluronic acid) |
|---|---|---|
| Mechanism | Relaxes the orbicularis oris muscle to evert the upper lip | Injects HA gel directly into lip tissue to add volume and structure |
| Adds physical volume | No | Yes |
| Primary target concern | Upper lip that disappears on smiling; gummy smile | Volume loss; thin lips; definition; asymmetry |
| Result onset | 10 to 14 days for full effect | Immediate; refined over 2 to 4 weeks as swelling settles |
| Typical duration | 6 to 12 weeks | 6 to 12 months |
| Reversible | No - must wait for it to wear off | Yes - hyaluronidase dissolves HA filler |
| Gummy smile correction | Yes, by limiting upper lip elevation | No |
The core distinction: one addresses muscle, the other addresses volume
The decision between a lip flip and lip filler is not primarily a decision about risk, price or pain tolerance, though all of those are relevant secondary considerations. It is a decision about the nature of the underlying concern.
Patients often tell me their concern is "my lips look thin." But thinness is not a single phenomenon. It can mean:
- The upper lip disappears when smiling because the orbicularis oris pulls it inward (a muscle-positioning issue, where a lip flip may help)
- The lips have lost volume over time and look deflated or smaller than they used to (a volume issue, where filler is more appropriate)
- The upper lip has always been less prominent and the patient wants more visible definition (potentially either, depending on assessment)
- There is asymmetry between the upper and lower lips (often a volume issue)
In my experience, patients rarely arrive with an accurate diagnosis of their own concern - and the published literature backs that up. Someone who asks for a lip flip may, on assessment, be better served by conservative filler. Someone who asks for filler may find that a lip flip alone achieves what they wanted. The consultation and what I see in front of me determine the right approach, not the treatment name the patient arrived with.
This is why the decision framework below starts not with "which treatment do you prefer?" but with "what is the actual concern?"
Working out which treatment fits your situation
If your upper lip disappears when you smile: This is one of the clearest indicators for a lip flip. The disappearance is caused by the orbicularis oris pulling the lip inward and upward during smiling, which hides the pink lip surface. Relaxing the muscle partially allows more lip to remain visible throughout the smile. A lip flip is designed for exactly this concern.
If you show more gum than you would like when you smile: Again, a lip flip is the appropriate primary treatment. By limiting how far the upper lip elevates, it reduces gum exposure. Note that if gummy smile is your primary concern, the dedicated gummy smile correction treatment at HSI may offer a more targeted approach and is worth discussing in consultation.
If you want your lips to look visibly fuller: Filler. A lip flip will not make your lips larger. It makes more of your existing lip visible. If the goal is genuine increased volume, hyaluronic acid filler is the treatment designed for that outcome.
If you have lost volume in your lips over time: Filler. Age-related volume loss is a tissue and structural change, not a muscle-positioning change. Filler replaces the physical material that has been lost.
If you have thin lips and have never had any injectable treatment: Both options deserve consideration at consultation. A lip flip provides a lower-commitment, shorter-duration starting point that allows you to assess how you respond to any change before committing to filler. That said, if your lips are genuinely thin and you want noticeable improvement, a lip flip alone may not deliver enough change, and filler is likely the more direct route.
If your primary concern is the shape or definition of the lip border rather than volume: Filler. Defining the vermillion border, refining the Cupid's bow, or correcting lip asymmetry all require material to be placed, which is what filler provides.
If maintenance frequency matters to you: Lip filler typically requires top-up appointments once or twice a year. A lip flip, with its shorter duration, requires more frequent visits to maintain the result continuously. This is worth factoring into the decision alongside per-session cost.
When combining both treatments makes sense
The Pitchford 2025 systematic review notes that some practitioners advocate combining botulinum toxin lip flip with hyaluronic acid lip filler for enhanced results. The rationale is straightforward: the lip flip allows the upper lip to evert and sit in a better position, and the filler then adds volume to a lip that is already showing more of itself. The two effects work together rather than independently.
This combination approach tends to suit patients who want subtle but visible comprehensive lip enhancement, who have a relatively tight upper lip that does not show much vermillion at rest, or who want a modest volume increase without the risk of the result looking overfilled.
Whether the combination is right for you, and how each treatment would be sequenced and dosed, is something I assess at consultation. The point here is that the two treatments are not mutually exclusive, and choosing one does not rule out the other, either in the same session or at a later stage.
When neither treatment alone fully addresses the concern
There are situations where a lip flip and lip filler, individually or together, are unlikely to resolve what you are hoping to change.
If the upper lip sits close to the nose because the philtrum is long: A long philtrum (the vertical distance between the base of the nose and the upper lip border) is an anatomical structure, not a muscle or volume issue. Neither botulinum toxin nor hyaluronic acid changes philtral length. A surgical lip lift, which shortens the philtrum and increases tooth show, addresses this concern in a way that non-surgical treatments cannot. I identify this at consultation rather than proceeding with a treatment that would not meet the patient's goals.
If the primary concern is the corners of the mouth: Downturned mouth corners are a separate anatomical concern from the upper lip. Specific botulinum toxin placement to the depressor anguli oris muscle, or filler to the corner area, addresses this differently from a standard lip flip. Raising this at consultation allows me to plan the right combination of treatment sites.
If there is significant perioral skin laxity: Deep perioral lines from long-term skin laxity are not fully resolved by lip flip or filler alone. Other skin quality or resurfacing treatments may be more appropriate, either instead of or alongside injectables.
In all of these situations, a face-to-face consultation identifies the mismatch between the treatment being considered and the actual concern, before anything takes place.
Wondering whether your concern is actually a lip flip or filler issue - or something else entirely?
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A note on pricing
Both lip flip Botox and lip filler are available at Harley Street Injectables. Current pricing for both treatments is on our price list. As a general direction only: a lip flip uses a small number of botulinum toxin units and is typically one of the more accessible-cost lip treatments; lip filler is priced by volume and is higher per session, though the longer duration affects the annual cost comparison. Discuss the full cost picture, including maintenance frequency, at your consultation.
Frequently asked questions
What exactly does a lip flip do?
A lip flip uses a small quantity of botulinum toxin injected into the orbicularis oris muscle along the upper lip border. Partially relaxing this muscle allows the upper lip to roll slightly outward, revealing more of the pink lip surface and creating the appearance of a more visible, slightly fuller upper lip. It does not add any physical volume. A 2026 prospective study measuring outcomes objectively by stereophotogrammetry found a statistically significant increase in upper lip height with no change in lip volume, confirming that the mechanism is positional, not volumetric.
What are the downsides of a lip flip?
The main downsides are its short duration, the absence of any volume change, and the temporary functional effects that can occur while the botulinum toxin is active. Published studies consistently document temporary difficulty drinking from a straw and whistling during the weeks the treatment is in effect. These are mild and self-resolving. A lip flip also cannot be reversed if you dislike the result; you wait for it to wear off. Patients who play wind instruments or who rely on precise lip control for their work should discuss this before proceeding.
How long does a lip flip last compared to lip filler?
A lip flip lasts considerably less time than lip filler. The oral musculature is highly active, contributing to faster metabolisation of botulinum toxin at this site compared with less mobile areas. Published clinical observations suggest effects begin to fade from around six to eight weeks, with full return of normal muscle activity typically by two to three months. Lip filler, by contrast, typically lasts six to twelve months in clinical practice, though this varies by product, volume and individual.
What hurts more, a lip flip or lip filler?
Lip filler typically involves more discomfort than a lip flip, for straightforward anatomical reasons. The lip flip uses a very fine needle and a small number of injection points just above the upper lip border, with minimal product volume. Most patients describe it as a brief, mild sting. Lip filler involves multiple injection points across a more sensitive area (the lips contain a high density of sensory nerve endings), and the injection of a denser gel creates more pressure in the tissue. Topical anaesthetic is standard before lip filler; it is often not needed for a lip flip. Individual pain tolerance varies considerably, and both treatments are well-tolerated by most patients.
Can you have a lip flip and lip filler together?
Yes. The treatments can be performed in the same session or at separate appointments. Published literature notes that some practitioners advocate combining both for enhanced results, with the lip flip allowing the upper lip to evert and the filler adding the volume to a lip that is already sitting in a more favourable position. Whether this combination is appropriate, and how it would be sequenced and dosed for your specific anatomy, is a clinical decision for your consultation.
Who is not a good candidate for a lip flip?
A lip flip uses botulinum toxin, a prescription-only medicine in the UK, which must be prescribed by a qualified prescriber following a face-to-face assessment. People who are pregnant or breastfeeding should avoid botulinum toxin treatments as a standard precaution. Those with neuromuscular conditions such as myasthenia gravis should not receive botulinum toxin injections. Anyone with a previous allergic reaction to botulinum toxin or its excipients should discuss this with a prescriber before proceeding. People whose professional or personal activities require precise fine motor control of the lips, such as wind instrument musicians, should consider the temporary functional effects carefully. A lip flip is also unlikely to meet the goals of anyone wanting genuine volume increase, since it adds no material to the lips.
Glossary of terms
- Hyaluronic acid (HA): A naturally occurring molecule found throughout the body's connective tissue. In lip filler, an HA gel is injected to add volume and hydration. HA fillers can be dissolved with hyaluronidase if needed, making them reversible. ↩ back to text
- Orbicularis oris: The circular muscle that surrounds the mouth and controls lip movement. The lip flip targets its superficial fibres along the upper lip border, partially relaxing the muscle to allow the upper lip to roll outward. ↩ back to text
- Vermillion / vermillion border: The vermillion is the coloured, visible part of the lip - the pink or red surface. The vermillion border is the boundary between this lip tissue and the surrounding skin. Defining or sharpening this border requires filler, not a lip flip. ↩ back to text
Sources
- Pitchford CA, Desrosiers AS, Tolkachjov SN. The lip flip: a systematic review of botulinum toxin lip augmentation. Archives of Dermatological Research. 2025;317(1):765. DOI: 10.1007/s00403-025-04265-0. PMID: 40377719.
- Germani M, Munoz-Lora VRM, Roschel P, Cotofana S et al. Lip flip revisited: clinical outcomes and neuromodulatory basis of upper lip eversion. Aesthetic Plastic Surgery. 2026;50:4437-4440. DOI: 10.1007/s00266-026-05727-0. PMID: 41915065.
- Wen YE, Perez Rivera LR, Wyatt HP, Lee WY, Oh C, Boyd CJ, Karp NS. Efficacy and safety of hyaluronic acid lip fillers: a systematic review and meta-analysis of randomized controlled trials. Aesthetic Surgery Journal. 2025. DOI: 10.1093/asj/sjaf224.
- Teixeira JC, Ostrom JY, Hohman MH, Nuara MJ. Botulinum toxin type-A for lip augmentation: "lip flip." Journal of Craniofacial Surgery. 2021;32:e273-e275. DOI: 10.1097/SCS.0000000000007128. PMID: 33170825.
- Bourmand R, Olsson SE, Soleimani S, Fijany A. Lip filler versus "lip flip": longitudinal public interest and a brief review of literature. Journal of Cosmetic Dermatology. 2025;24:e70048. DOI: 10.1111/jocd.70048.
Alice Henshaw, RN, NMP, is the Founder and Medical Director of Harley Street Injectables, a CQC registered clinic at 106 Harley Street, London. A registered nurse and independent prescriber (V300) with a Bachelor of Nursing and a Level 7 Diploma, she has more than a decade of international experience in medical aesthetics and is registered in the UK, Australia and New Zealand. She is a qualified skin biologist, a Key Opinion Leader for Allergan Aesthetics, a trainer and speaker, and the founder of SkinCycles skincare. Read more about Alice Henshaw.
Related reading: The conversation before the needle | Lip flip Botox at Harley Street Injectables | Lip filler at Harley Street Injectables
All injectable and device-based treatments carry risks, and results are not guaranteed. Individual anatomy and medical history affect outcomes. Always attend a face-to-face consultation before any procedure. Treatments referenced in this article are performed at Harley Street Injectables by qualified practitioners. This article is not a substitute for professional medical advice. It does not constitute medical advice. For personalised treatment recommendations, please book a consultation at Harley Street Injectables.
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