The unit dose for Botox depends on muscle strength; stronger foreheads may need more to achieve the same smoothing as
https://www.scribd.com/document/996592886/Wrinkle-Smoothing-Secrets-Botox-Facial-Smoothing-Guide-152918
The unit dose for Botox depends on muscle strength; stronger foreheads may need more to achieve the same smoothing as lighter musculature.