Lip Flip Revisited: Clinical Outcomes and Neuromodulatory Basis of Upper Lip Eversion

The lip flip procedure, involving intramuscular injection of botulinum toxin into the orbicularis oris, has gained popularity as a minimally invasive alternative to lip fillers. In this prospective study, 17 women underwent standardized upper lip neuromodulation with 4U of onabotulinumtoxinA. Objective evaluation by stereophotogrammetry demonstrated a modest but significant increase in upper lip height at 15 days (p=0.011), with no change in lip volume. Patient-reported outcomes showed significant improvement in perioral appraisal scores (p<0.001) and high satisfaction (FACE-Q mean = 79.2 ±19.9; GAIS median = 1). All adverse events were mild and transient, including temporary numbness and functional limitation, resolving spontaneously within 30 days. These findings confirm that lip flip enhances lip projection through selective neuromodulation, not volumetric augmentation. LEVEL OF EVI"DENCE IV: Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .