Lip flip and lip filler compared

A lip flip relaxes a muscle, a filler adds volume. How the two work, what each can and cannot do, and why the risk profiles differ.

Two treatments, two mechanisms

Lip flip and lip filler are often mentioned in the same breath, but they work in completely different ways. A lip flip uses very small doses of botulinum toxin placed in the orbicularis oris, the ring muscle around the mouth. A lip filler, usually made of cross-linked hyaluronic acid, is a gel injected into the lip to add volume. One changes muscle tension, the other changes the amount of tissue.

How a lip flip works

The orbicularis oris pulls the lips together and slightly inward, for example when speaking or drinking through a straw. In some people, this pull makes the upper lip roll inward, so less of the red part of the lip is visible, especially when smiling. When small amounts of botulinum toxin relax the muscle fibers just above the lip border, the upper lip can roll slightly outward. The lip looks a little fuller, but no volume is added.

The effect is subtle by design. A lip flip leaves the shape and size of the lip as they are and changes how much of the existing lip is shown. Because the doses around the mouth are kept deliberately small, some people notice the effect fading sooner than in the upper face.

How a lip filler works

A hyaluronic acid filler binds water and physically fills space. It can add volume, define the lip border or change proportions, effects that a lip flip cannot achieve. Hyaluronic acid fillers can be dissolved with the enzyme hyaluronidase if needed. However, research with imaging and tissue analysis has shown that cross-linked hyaluronic acid can remain in tissue considerably longer than the months often quoted, and repeated treatments can change the tissue over time.

Side by side

	Lip flip	Lip filler
Principle	Relaxes the lip muscle	Adds volume with a gel
Visible change	Upper lip rolls slightly outward	More volume and definition
Onset	Gradual, full effect at about 2 weeks	Immediate, swelling for a few days
Typical side effects	Temporary difficulty with straws, whistling or some sounds	Swelling, bruising, lumps
Rare serious risks	Temporary asymmetry of the mouth	Vascular occlusion, migration, nodules

What to expect after a lip flip

Because the muscle around the mouth is involved in speaking, eating and drinking, a lip flip can briefly affect these functions. Drinking through a straw, whistling, or pronouncing sounds like “p” and “b” may feel slightly different for the first days or weeks. A careful, low dose keeps these effects small, and they disappear as the effect wears off. People who rely heavily on their lips professionally, such as wind instrument players or singers, should mention this in the consultation.

Why HALO does not offer fillers

Fillers carry a different risk profile from neuromodulators. The rare but serious complication of filler injections is vascular occlusion, where material blocks a blood vessel and can damage the tissue it supplies. The lips are a well-supplied area where this risk has to be taken seriously. Beyond acute risks, migration and changes in tissue structure after repeated treatments have been described. HALO therefore does not offer filler treatments and focuses on muscle-based and regenerative approaches. The reasoning is explained in Neuromodulators vs. fillers.

Lip lines are a separate topic

Fine vertical lines on the upper lip, sometimes called smoker’s lines or plissé lines, are caused by the same ring muscle combined with collagen loss. Very small doses can soften the muscle component (see vertical lip lines); sun protection and skin quality treatments address the rest. Which approach suits your lips depends on anatomy, expectations and medical history, and is decided in a physician consultation.

References

Pitchford CA, Desrosiers AS, Tolkachjov SN. The lip flip: a systematic review of botulinum toxin lip augmentation. Arch Dermatol Res. 2025;317(1):765. PMID 40377719.
Germani M, Munoz-Lora VRM, Roschel P, et al. Lip Flip Revisited: Clinical Outcomes and Neuromodulatory Basis of Upper Lip Eversion. Aesthetic Plast Surg. 2026;50(11):4437-4440. PMID 41915065.
Kroumpouzos G, Treacy P. Hyaluronidase for Dermal Filler Complications: Review of Applications and Dosage Recommendations. JMIR Dermatol. 2024;7:e50403. PMID 38231537.
Master M, Azizeddin A, Master V. Hyaluronic Acid Filler Longevity in the Mid-face: A Review of 33 Magnetic Resonance Imaging Studies. Plast Reconstr Surg Glob Open. 2024;12(7):e5934. PMID 39015357.
Sito G, Manzoni V, Sommariva R. Vascular Complications after Facial Filler Injection: A Literature Review and Meta-analysis. J Clin Aesthet Dermatol. 2019;12(6):E65-E72. PMID 31360292.
Convery C, Davies E, Murray G, et al. Delayed-onset Nodules (DONs) and Considering their Treatment following use of Hyaluronic Acid (HA) Fillers. J Clin Aesthet Dermatol. 2021;14(7):E59-E67. PMID 34840652.
Semchyshyn N, Sengelmann RD. Botulinum toxin A treatment of perioral rhytides. Dermatol Surg. 2003;29(5):490-5; discussion 495. PMID 12752516.