Lip Flip with Botulinum Toxin Vs Hyaluronic Acid Filler: Indications, Outcomes, And Patient Selection: Case Reports

Minimally invasive procedures for lip enhancement have gained increasing relevance in aesthetic surgery, with hyaluronic acid fillers and botulinum toxin type A representing two treatment options with distinct mechanisms of action, indications, and therapeutic goals. While hyaluronic acid allows direct modification of lip volume, projection, contour, and definition, the so-called lip flip uses botulinum toxin to partially modulate the activity of the orbicularis oris muscle, promoting lip eversion and greater vermilion show without directly increasing lip volume. We present two clinical cases of patients who underwent lip enhancement procedures following static and dynamic assessment of the perioral region. In the first case, decreased upper lip volume and projection were identified; therefore, hyaluronic acid filler was administered, resulting in improved lip volume, definition, and proportions. In the second case, adequate lip volume was observed at rest, with decreased upper vermilion show during smiling secondary to dynamic lip inversion. A lip flip was therefore performed through the selective administration of botulinum toxin type A, resulting in increased vermilion show without the addition of volume. Both procedures achieved aesthetic improvement consistent with the individual anatomical and dynamic characteristics of each patient, with no major complications observed during follow-up. These cases emphasize that the choice between hyaluronic acid filler and botulinum toxin should not be based solely on the patient's desire to achieve the appearance of fuller lips, but rather on identifying the predominant anatomical or dynamic component responsible for the aesthetic concern. Individualized assessment both at rest and during smiling allows differentiation between structural deficiencies and dynamic abnormalities, thereby facilitating the selection of a targeted treatment. Hyaluronic acid is particularly useful when modification of lip volume, projection, or definition is required, whereas the lip flip represents an alternative for selected patients with adequate baseline lip volume and dynamic inversion of the upper lip. Appropriate patient selection, thorough knowledge of perioral anatomy, and the establishment of realistic expectations are essential to achieve harmonious, functional, and safe outcomes.