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Review
. 2025 Oct;24(10):e70508.
doi: 10.1111/jocd.70508.

A Psychological Guide to Upper Face Botulinum Toxin Injections: Baseline Emotional Functions of Facial Expressions

Alexander G M Hopf  1 , Anna Buchheim  1 , Marietta Hopf  2 , Mia Cajkovský  3 , Dirk W Eilert  1
Affiliations
Review

A Psychological Guide to Upper Face Botulinum Toxin Injections: Baseline Emotional Functions of Facial Expressions

Alexander G M Hopf et al. J Cosmet Dermatol. 2025 Oct.

Abstract

Background: The upper face is central to human nonverbal communication, with the glabellar complex, forehead, and lateral canthal area signaling core emotions such as anger, sadness, fear, surprise, and joy. Botulinum toxin type A (BoNT-A) is widely used to modulate muscle activity in these regions, not only reducing dynamic wrinkles but also affecting emotional expression and perception.

Aims: The aim of this narrative review is to synthesize psychological and neurobiological insights into a region-focused framework, helping clinicians incorporate emotional considerations into BoNT-A treatments of the upper face.

Methods: A narrative literature review was conducted using PubMed and Scopus, combining the search terms "botulinum toxin", "facial expression", "emotion", "mimicry" and "psychology". Peer-reviewed articles addressing facial Action Units (AUs), neural mechanisms, or psychological outcomes were included. Citation tracking and the authors' clinical expertise further informed the synthesis.

Results: The upper face is integral to various facial expressions, with each region contributing distinct signals relevant to intrapersonal experience and interpersonal communication. BoNT-A can alter these facial expressions, with potential benefits such as mood enhancement, but also possible limitations in conveying authenticity. While neuroimaging and behavioral findings support links between facial feedback and limbic activity, systematic data on region-specific psychological outcomes remains scarce.

Conclusions: Understanding baseline emotional functions of facial expressions is crucial for clinicians, as these movements shape intrapersonal experience and interpersonal communication. Integrating this knowledge into counseling enables transparent, well-informed discussions before BoNT-A application. Future research should systematically evaluate expressive flexibility and patient-reported satisfaction with emotional communication.

Keywords: botulinum toxin; expressive flexibility; facial emotions; facial expressions; facial feedback hypothesis.

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Conflict of interest statement

A.G.M.H. is Director of International Professional Education at Evolus Inc., Newport Beach, California, USA.

A.G.M.H. is an employee of Evolus Inc., Newport Beach, California, USA. M.H. is a speaker for Croma Pharma, Leobendorf, Austria. The other authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Flowchart depicting PubMed/Scopus search strategy and inclusion criteria. Two evidence streams informed this narrative review: (i) the BoNT‐A evidence stream identified through database screening, and (ii) region‐specific baseline emotional function literature incorporated through citation tracking and prior knowledge.
FIGURE 2
FIGURE 2
Illustrative photographic depiction of the glabellar complex at rest (A) compared to activation (B) leading to a medial and downward movement of the eyebrows, intensifying glabellar lines.
FIGURE 3
FIGURE 3
Illustrative photographic depiction of the differentiation of three different upper face expressions involving the frontalis muscle. (A) Neutral; (B) inner brow raiser (AU1); (C) full brow raise (AU1+2); (D) brow raise with brows drawn together (AU1+2+4).
FIGURE 4
FIGURE 4
Illustrative photographic depiction of the lateral canthal region when performing a social smile (A) vs. when performing an authentic (Duchenne) smile (B).
See this image and copyright information in PMC

References

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