Can regular Botox injections lead to permanent muscle weakness or atrophy over time?

Yes, but this is a medically controlled and desired effect. When a muscle doesn’t contract for a long time, it biologically begins to lose volume and thin; this is called muscle atrophy. In people who regularly receive Botox injections (for example, continuously for 3-4 years), the muscles in the forehead or between the eyebrows thin and forget how to contract, so even after the effect of Botox wears off, the person cannot make their old strong facial expressions, and the rate of new wrinkle formation in that area slows down significantly. This does not permanently impair facial expression; on the contrary, it provides a long-term protective advantage in wrinkle treatment.