Enhancing Patient Comfort in Aesthetic BoNT-A Injections: Mechanical Versus Topical Analgesia

Botulinum toxin type A (BoNT-A) is widely used in aesthetic medicine to treat dynamic facial rhytides. Despite its well-established safety and efficacy, BoNT-A injections often induce discomfort and anxiety owing to injection-related pain, especially in sensitive facial areas. Although topical anesthetic creams are commonly employed to alleviate pain, they have limitations, such as delayed onset and local side effects. Mechanical analgesic devices, based on the gate control theory of pain, have emerged as promising non-pharmacological alternatives.

In this prospective, single-center, split-face study, 80 adult patients undergoing upper-facial BoNT-A injections between May 2024 and August 2025 were enrolled. Each participant received a topical anesthetic cream on one side of the face and a Shot Blocker-like mechanical analgesic device on the contralateral side. All injections were administered by a single experienced physician. Pain levels were assessed immediately post-injection using a visual analog scale (VAS, 0-10) by a blinded evaluator. Statistical analyses included paired t-tests, Wilcoxon signed-rank tests, Spearman correlation, and Mann-Whitney U tests. Effect sizes were reported using Cohen's dz and Cliff's Δ.

Mean VAS scores were significantly lower with the mechanical device (3.19 ± 1.08) than with the topical cream (4.14 ± 1.30) (p < 0.001). The intra-individual mean difference (0.95 ± 1.41) favored the mechanical device. Spearman's correlation indicated that higher pain scores with the cream correlated with greater relative benefit from the device (ρ = 0.664, p < 0.001). Patients with higher baseline pain (VAS ≥ 4 on the cream side) experienced significantly greater pain reduction (p < 0.001).

A shot blocker-like mechanical analgesic device is more effective than a topical anesthetic cream in minimizing pain during BoNT-A injection into the upper face. Its immediate analgesic effect, absence of pharmacologic side effects, and ease of use make it a valuable adjunct in aesthetic practice, particularly for patients with pain sensitivity. Further studies are warranted to validate these findings in broader populations and different anatomical regions.

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