Botulinum neurotoxin for lip flip.

Botulinum neurotoxin (BoNT) injection for "lip flip" is used to achieve subtle upper lip eversion by partially relaxing the pars marginalis of the upper orbicularis oris. This short communication describes the anatomical rationale, injection approach, and early clinical observations in three consecutive patients treated with LetybotulinumtoxinA. BoNT was reconstituted to 4 U/0.1 mL and injected superficially along the upper vermilion border, with 1 U per site, avoiding the oral commissures and deeper muscle layers. At two weeks, all patients showed subtle upper lip eversion and reduction of vertical rhytides, with satisfaction ranging from "Satisfied" to "Very Satisfied." No patient reported speech disturbance, difficulty with oral movement, asymmetry, or oral incompetence during the short follow-up. These findings should be interpreted as preliminary because of the very small sample size, lack of control group, absence of blinded assessment, and short follow-up.