The Long-Term Efficacy of Botulinum Toxin Type A for Lower Facial Rejuvenation in 400 Patients

Abstract

Background: Botulinum toxin type A (BoNT-A) has become an established treatment for upper facial rejuvenation; however, its use in the lower face and neck is less explored and presents anatomical challenges. This study evaluates the long-term efficacy and safety of BoNT-A injections for lower facial rejuvenation, emphasizing potential cumulative effects and muscle modulation.

Methods: A retrospective single-centre analysis was conducted on 400 patients (380 females and 20 males; aged 35-85 years) treated between January 2018 and December 2024. Patients received, during a full face treatment, BoNT-A injections targeting the mentalis, depressor anguli oris, platysmal bands, and masseter muscles, with standardized doses ranging from 120 to 160 units per session every 6 months. Patients underwent a minimum of three sessions over a follow-up period of 24-60 months. Outcomes were assessed using the Merz Aesthetic Scale (for platysmal bands) and a 5-point Visual Analogue Scale (VAS) based on standardized pre-treatments photographic and video documentation reviewed by two independent plastic surgeons.

Results: The mean Merz score reported these results baseline (pre-first treatment): 4.2 ± 0.6, after first cycle: 2.1 ± 0.4 (p < 0.01), and after third cycle: 1.8 ± 0.3 (p < 0.001 compared to baseline). Independent VAS ratings confirmed significant improvements in contour and soft tissue balance Global improvement score: pre-treatment 1.5 ± 0.7 → post-treatment 4.1 ± 0.4 (p < 0.001). Notably, patients maintained results longer than the expected pharmacological effect window, supporting the hypothesis of functional muscle retraining. Mild adverse events occurred in less than 12% of patients, mainly localized bruising and discomfort, with no serious complications.

Conclusions: In this large cohort of 400 patients, BoNT-A injections for lower facial rejuvenation produced significant aesthetic improvements with progressive and sustained benefits over time. The concept of cumulative neuromodulation offers new insight into long-term lower face aesthetic management. Our results support BoNT-A as a safe, effective, and minimally invasive treatment option in expert hands.

Level of evidence ii: This journal requires that authors 43 assign a level of evidence to each article. For a full 44 description of these Evidence-Based Medicine ratings, 45 please refer to the Table of Contents or the online 46 Instructions to Authors http://www.springer.com/00266 .

Keywords: BoNT-A; Botox; Cosmetic medicine; Full face.