The lip flip: a systematic review of botulinum toxin lip augmentation.

The cosmetic use of botulinum toxin type-A (BTA) has expanded to include the "lip flip" procedure, which enhances lip contour and fullness without adding volume. This minimally invasive and cost-effective technique offers a favorable safety profile for patients seeking subtle lip enhancement. This review systematically examines the technique, clinical outcomes, and safety of the lip flip through neuromodulation with BTA. A comprehensive literature search was conducted using PubMed and Ovid, identifying 48 articles, of which seven met inclusion criteria detailing injection sites and dosages. The procedure typically involves injecting 4-6 units of BTA into the orbicularis oris muscle, resulting in consistent upper lip eversion and improved contour. Patients report high satisfaction and minimal downtime, with mild and transient side effects such as difficulty whistling or drinking through straws resolving within weeks.