Studies show on average results will start to decline at the six-week mark but will not be noticeable until around the twelve-week mark. At this time it is usual to treat the area again. Some people will need treatment sooner while others may enjoy results that last much longer than three months.
The effects usually last between 3 to 4 months. If you have regular muscle relaxer treatments, the effects may last longer.
Muscle relaxer injections relax only the muscles beneath the lines where the product has been placed and the muscles responsible for other aspects of your facial expression stay active. If you have no further treatments, the muscles return to normal and lines gradually go back to how they looked before treatment.