Two weeks after receiving the injections to the frontalis muscle, the group of patients (who were between 29 and 66 years old) showed a significant increase in forehead height. ... The shorter your forehead to begin with, the more dramatic the results.

Does Botox change your forehead?

"If you do too much Botox on your forehead for many, many years, the muscles will get weaker and flatter," cautions Wexler, adding that the skin can also appear thinner and looser. Moreover, as your muscles become weaker, they can start to recruit surrounding muscles when you make facial expressions.

Why does Botox make forehead look bigger?

Injections of Botox do Lengthen Foreheads

Injections of botulinum toxins appear to lengthen your forehead. The reason why Botox works so well at creating longer forehead and brow lift is that it relaxes the forehead muscles. The relaxed muscles no longer pull the skin downwards.