FDA Accepts sBLA for Botox Cosmetic in Masseter Muscle Prominence

The FDA has accepted for review a supplemental Biologics License Application (sBLA) from Allergan Aesthetics, an AbbVie company, for Botox Cosmetic (onabotulinumtoxinA) to treat marked to very marked masseter muscle prominence (MMP) associated with masseter muscle activity in adults.¹ If approved, Botox Cosmetic would become the first and only neurotoxin indicated for this condition in the US and would expand the product's aesthetic portfolio to a fifth approved indication.¹

How is the submission supported?

The sBLA is supported by two phase 3 clinical studies, M21-416 and M21-417, both of which met their primary endpoints and demonstrated statistically significant improvements in the severity of masseter muscle prominence compared with placebo (p=0.0046 and p=0.0014, respectively).¹ Patient satisfaction outcomes also favored treatment, with twice as many patients treated with Botox Cosmetic reporting they were "very satisfied" or "satisfied" compared with those who received placebo.¹ The safety profile observed in the studies was consistent with Botox Cosmetic's established uses, and no new safety signals were identified.¹

Why does this indication matter clinically?

Masseter muscle prominence can contribute to the appearance of a wider or more square lower face, and the submission is aimed at a growing category of non-surgical facial contouring requests.¹ Botulinum neurotoxin type A injection into the masseter muscle is an established off-label lower-face contouring technique, with published literature describing sustained volume reduction and improved facial harmony following treatment.²'³

Botulinum toxin type A works by blocking acetylcholine release at the neuromuscular junction, inducing temporary muscle relaxation and, with repeated treatment, gradual atrophy of the injected muscle; in the masseter, this process reduces muscle bulk over successive treatment cycles rather than requiring surgical intervention, a mechanism first characterized in early studies of masseteric hypertrophy treatment.²

Steve Yoelin, MD, a coordinating clinical investigator with more than 25 years of experience in minimally invasive medical aesthetics, said, "Patients are increasingly seeking overall facial assessments with non-surgical options to address aesthetic needs for the lower face. As facial assessment continues to evolve beyond individual treatment areas, this indication would further broaden the clinical utility of Botox Cosmetic, if approved, by providing an important new treatment option."¹

What did company leadership say?

Darin Messina, PhD, senior vice president and head of aesthetics research and development at AbbVie, said, "This submission builds on the depth and versatility of Botox Cosmetic and reflects our continued investment in advancing aesthetic medicine. At Allergan Aesthetics, our approach to innovation includes both developing new treatment options and continuing to expand the potential of established products. The pursuit of a fifth aesthetic indication demonstrates that commitment to addressing evolving patient needs."¹

What happens next?

The FDA's acceptance of the sBLA for review does not guarantee approval, and the company has not disclosed an expected action date. If approved, Botox Cosmetic would carry masseter muscle prominence alongside its four existing aesthetic indications: glabellar lines, lateral canthal lines, forehead lines, and platysma bands.¹

References

1. Allergan Aesthetics announces U.S. FDA acceptance of supplemental Biologics License Application for BOTOX Cosmetic for masseter muscle prominence. News release. Allergan Aesthetics, an AbbVie company; August 4, 2026. Accessed August 4, 2026.
2. Almukhtar RM, Fabi SG. The masseter muscle and its role in facial contouring, aging, and quality of life: a literature review. Plast Reconstr Surg. 2019;143(1):39e-48e. doi:10.1097/PRS.0000000000005083
3. Kundu N, Kothari R, Shah N, et al. Efficacy of botulinum toxin in masseter muscle hypertrophy for lower face contouring. J Cosmet Dermatol. 2022;21(5):1849-1856. doi:10.1111/jocd.14858