Written by Dr Callum Shields, MBChB Lead Clinician at Thriyv, Manchester
Fuller lips are one of the most requested aesthetic treatments in the world. Two procedures dominate the conversation: the Botox lip flip and lip filler. On the surface, they sound similar. Both are injectable, both are minimally invasive, and both promise a more prominent lip. But they work in fundamentally different ways, and the gap between them matters far more than most people realise before booking.
This article covers how each treatment actually works, where the lip flip consistently falls short, and why dermal filler is the more reliable choice for most patients, particularly when applied using more advanced placement techniques.
What is the Botox lip flip?
The Botox lip flip uses botulinum toxin A, the same neurotoxin used to smooth forehead lines, injected into the orbicularis oris, the circular muscle surrounding the mouth. A typical treatment uses around 4 to 6 units. When Botox relaxes this muscle, the upper lip curls gently outward, a movement known as eversion.
The key word here is illusion. The lip flip does not add volume. It repositions the lip so it appears more prominent at rest. Results begin showing within 3 to 5 days, with the full effect visible at around two weeks.
A 2025 systematic review of botulinum toxin lip augmentation confirmed that the procedure reliably creates upper lip eversion with a generally favourable safety profile. For patients whose upper lip disappears when they smile, or those wanting a very subtle, temporary change, it has a specific role. The limitations become apparent when patients expect more from it than its mechanism can actually deliver.
The shortcomings of the lip flip
Two significant drawbacks to the lip flip tend to be underemphasised in clinic consultations.
The first is longevity. The lip area sees more muscular activity than almost anywhere else on the face, speaking, eating, laughing. The body metabolises Botox here faster as a result. Longitudinal research comparing lip filler and lip flip outcomes found that while general facial Botox lasts three to four months, the lip flip typically wears off in six to eight weeks. Sustaining the effect means four or more appointments per year.
The second problem is more consequential: the lip flip interferes with how the mouth works.
The orbicularis oris is not a purely cosmetic muscle. It controls speech, chewing, drinking, and fine movements like whistling. Relaxing it with Botox affects all of those functions, not just the aesthetic ones. Patients regularly report difficulty pronouncing “p”, “b”, and “m” sounds, trouble drinking from a straw without spillage, and reduced ability to close the lips with any force. These effects last for the full treatment cycle not just the first week or two.
For anyone who uses their voice professionally, teachers, performers, public speakers this is a real quality-of-life consideration. It is not a rare complication; it is a direct consequence of the mechanism.
What is lip filler?
Lip filler works at a different level entirely. Rather than repositioning the lip through muscle relaxation, hyaluronic acid (HA) dermal filler adds actual volume and structure to the lip tissue.
Hyaluronic acid is produced naturally by the body. In the skin and connective tissue, its role is to attract and retain moisture. Cross-linked HA, when injected into the lips, creates immediate and measurable volume. A practitioner can use dermal filler to increase overall lip size, define the vermilion border, correct asymmetry, and treat both the upper and lower lip, none of which the lip flip addresses.
Results last considerably longer too. Most HA lip fillers hold for six to twelve months, and some formulations maintain their effect for up to eighteen months. A randomised controlled trial in 114 patients demonstrated long-term aesthetic improvement and safety with statistically significant outcomes at follow-up. If the result does not meet expectations, the filler can be dissolved using an enzyme called hyaluronidase, a meaningful safety advantage that Botox cannot offer while it is still active.
Research into patient satisfaction with HA lip filler found that over 89% of subjects reported satisfaction across all outcome measures at eight weeks post-treatment, including appearance, natural feel, and overall result.
Why lip filler is the more logical choice
The lip flip lasts six to eight weeks. Lip filler lasts six to twelve months. The lip flip relaxes a functional muscle and compromises it for the entire treatment period. Lip filler adds volume without touching muscle activity at all. The lip flip creates the appearance of fullness in the upper lip only. Lip filler creates actual fullness, in both lips if needed, with precise control over shape, volume, and definition.
When you put it that way, the choice is not particularly ambiguous for most patients.
A longitudinal analysis of Google Trends data from 2014 to 2024 found that “lip filler” consistently generated 2.5 times the search volume of “lip flip”, an average relative search volume of 30.4 versus 12.1. Patient interest has tracked steadily toward the treatment that lasts longer and does more.
The Swedish lip technique: a natural alternative
Patients who want a natural result, fuller, more lifted, but without the firmness or visible border that can come with more superficial filler placement, should know about the Swedish lip technique.
Rather than injecting filler directly into the lip tissue, this approach places the dermal filler behind the orbicularis oris muscle, in the sub-muscular plane. The product sits beneath the muscle rather than within it, creating gentle projection from below. The lip looks naturally fuller and more lifted, without the stiffness associated with conventional placement. More importantly, the orbicularis oris itself stays completely untouched. Speech, chewing, and whistling remain unaffected.
A clinical study of the Bi-Bi technique, which uses both sub-muscular and dermal planes in combination, found that dissociating the anatomical zones of the lip produced natural, lasting projection with high patient satisfaction and no significant complications. Because the product is placed in a lower-movement area, results can last as long as, or longer than, standard filler placement.
This is the natural result the lip flip is marketed to deliver. The Swedish lip technique actually delivers it, without the functional compromise, and without the six-to-eight-week clock.
Conclusion
The lip flip works for a narrow range of patients with specific goals: reducing a gummy smile, or trialling the idea of lip enhancement before committing to filler. For most people wanting a result that looks natural, lasts longer than two months, and does not affect their ability to speak or eat normally, lip filler is the more logical choice. Advanced techniques like the Swedish lip extend what dermal filler can achieve even further. A qualified aesthetic practitioner can assess your anatomy and help you decide what is right for your goals.
At Thriyv, all lip treatments are performed or directly overseen by Dr Callum Shields, MBChB — assessing your anatomy, your goals, and recommending the right approach for you.
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Dr Callum Shields, MBChB, is the Lead Clinician at Thriyv a premium, doctor-led aesthetics, wellness, and recovery clinic based in Manchester city centre. All aesthetic treatments at Thriyv are performed within a fully clinical environment, with patient safety and outcome quality at the centre of every decision.