Muscle- and Gland-Specific Dosing of Botulinum Toxin in Facial Aesthetics: Review of Dose Ranges, Target Depth, Muscle Thickness, and Neuromuscular or Glandular Anatomy

Botulinum neurotoxin type A (BoNT-A) dosing in facial aesthetics varies across anatomical targets, formulations, and treatment indications. This structured narrative review examined published dose ranges and the potential relevance of muscle thickness, target depth, functional anatomy, and injection localization to individualized treatment planning. English-language regulatory, clinical, anatomical, ultrasound, and consensus literature available through 13 April 2026 was considered. Evidence was interpreted according to source type, distinguishing approved product-specific regimens, controlled clinical studies, observational reports, and anatomy- or expert-derived recommendations. Muscle bulk may inform masseter contouring, but the literature does not establish a validated thickness-based dosing equation applicable across facial muscles. For facial expression muscles, contraction patterns, treatment objectives, and preservation of adjacent function are central considerations. Evidence for aesthetic dosing of the temporalis and salivary glands remains limited, and glandular indications require separate assessment from skeletal muscle treatment. Anatomically informed placement has a plausible mechanistic rationale, whereas evidence that motor-zone targeting consistently reduces toxin requirements is insufficient. Ultrasound may assist selected anatomically complex or previously treated cases but is not established as necessary for routine injections. Safe dose selection requires formulation-specific interpretation, indication-specific evidence, individualized anatomical assessment, and recognition of the limitations of existing studies.