What should I expect after Botox masseter for one month? Face slimmer or Botox starts to wear off?

IF you are unhappy with the cosmetic outcome you can add more to the jawline, but that is if you were a good candidate to begin with  the results are subtle and should be appreciated by overlapping the before and after photos.  

Botox is commonly injected into the muscle on the jawline to improve the pain and discomfort from grinding and to slim the jawline. Botox relax muscles over a one-week time period.  After this week, patients will typically experience improvement of their pain and soreness and feel the relaxation of the masseter muscle.  Shrinking of the jawline is secondary to atrophy of the masseter muscle. This process will occur over a 3 to 4 months time. I would wait until that time to judge the results. Before-and-after pictures can be helpful and objectively judging this limit of your jawline secondary to Botox in your masseters.I hope this helps

Botox for masseter is extremely effective at slimming the jawline when good relaxation of the muscle is achieved.  Especially since you have noticed your masseters have gotten softer, the muscle will show a visible difference in size over the 3-4 months that the Botox is active.  Most patients will see a slimming effect in 4-6 weeks after treatment, but rest assured that the muscle will continue to slim over the next 3-4 months.