The extent that brows descend after botulinum toxin injections is greatly influenced by the amount of frontalis weakening, according to a small study by German researchers published May 2019 in the Aesthetic Surgery Journal.

German researchers used three-dimensional (3D) technology to evaluate eyebrow position after treatment with abobotulinumtoxinA (Azzalure, Galderma). They studied two groups of adult women: one group received glabella-only injections; the other received glabella plus frontalis muscle injections. Researchers measured brow position pre-injection and at 2 weeks, 3 months and 6 months post injection.
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