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.

Botox can take from a few days to two weeks to start working. For masseter reduction, it is dependent upon number of units you were treated with and what sort of expectations you have and discussed with your provider. It can take several months, and you need to continue treatment to maintain the reduction.

The Botox will take effect within 2 weeks after injection. Once the masseter muscle has completely relaxed, the reduction of the muscle will occur over the following 2-4 weeks. Most patients notice changes at the 1-2 month follow up.

 

Repeat treatments help to maintain results and prolong duration of effect.

You will notice a reduction in muscle activity at ~3 days after the injection, and will see maximal effects at ~7 days after injection.  Depending on the dosage administered, you may have residual masseter activity even when the Botox or Dysport is fully active.  Especially in patients with very large masseters, it may take a two or more treatments with Botox or Dysport to achieve the maximal result.  Re-treatment at 1 month after the initial injection works well to reduce residual activity.

Long-term muscle atrophy and size reduction will be noted after serial treatments with Botox/Dysport.  The initial loss in size will simply come as a result of the muscle's inability to contract.  

It takes 1 week for Botox to work. The peak effect is seen at 30 days. We usually see improvement in treating the Masseter after the second session, which is 3 months following the initial treatment.- Dr. Gross

This is a great indication for the use of Botox which I believe is underutilized. While Botox will start working within the first 72 hours, the overall reduction in the size of the masseter muscle will take months and will need multiple treatments to maintain reduction of moment and atrophy of the muscle.

Botox is a great option to shape the lower face in someone with bulky masseter muscles. Botox works in muscles of facial expression in a few days because the improvement results from softening of the muscle movement. Botox treatment of the masseter muscle can require several months to achieve benefit because slimming relies upon atrophy and shrinkage of the masseter muscle which takes significantly more time. In properly selected patients, this is a great treatment option but, as you hinted at, is not immediate. I hope this information is helpful.Stephen Weber MD, FACS

Botox can be used effectively to treat large masseter muscles.  Once injected, it will only take a matter of days to a week for the Botox to begin working.  After this time, you should notice that the masseter muscle does not clench up as much as before the treatment.  It can take a matter of months to see further reduction in the size of the muscle however.  Like any muscle, once it is not exercised, it will reduce in size over a period of months.