How Long Does Botox Take to Work in the Masseter Muscles?

Thank you for your question.  Botox in the masseter region usually takes longer than in the standard areas to take effect.  I tend to use anywhere from 15 units (conservative treatment) to 50 units (for someone with really strong masseters) on each side to get the desired result.  It may start within the first week but  I tell my patients to wait three weeks before doing a more thorough evaluation.  The treatment typically lasts longer than the forehead/crows feet/frown regions. It is also a gradual onset of the return of masseter function. I have tried the masseter injections myself and space the treatments around 4 months apart, but use smaller doses to maintain the effect. I normally know the effects are wearing down when I start to clench my teeth more heavily at night when asleep.

Botox usually takes 2 or 3 days to start to work, and will continue to improve over the first 7 to 10 days. The improvement will last up to 6 months. Once the effect starts to wear off, you will need a repeat treatment to maintain your result. Some find that the effects last longer after having multiple treatments, even up to a year.

   Masseter reduction occurs over months to years, although the Botox begins to work in several days to a week.