How long does it take for masseter Botox to work?

This takes 3-6 weeks to see the full effect.  Often 30-60 units per side are needed and even more if the end result is even further contouring.  I wait 3-6 weeks and then reassess the need for more. Before and after pictures best tell if there is a change. Best, Dr. Emer.

It is better to go slowly when treating the Masseter to achieve consistent, symmmetrical results. Secondary treatment with decreased dose may do the trick. Stay patient and Good luck!

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.I would definitely take before and after pictures to assess the visual effect as it is hard to appreciate the change from one day to the next. It would also be great to share them online if you are comfortable as it might help us give more insight as to why it didn't work.

The first time injection of Botox will soften the masseter muscle but will not necessarily reduce it in its size.  As you keep repeating it over years eventually the size of the muscle will reduce from atrophy of the muscle.Even after the first time you will see some improvement within 2-3 months.RegardsDr. J

Unlike regular wrinkle injections, the effect of injections in the masseters takes about 4-6 weeks before you see the difference and typically last between 4-6months before needing another treatment. 

This muscle is quite large compared to the other areas commonly treated with Botox. I often have patients who don't see a noticeable difference until the second treatment  (4 months) It takes a while for the muscle to atrophy. It does sound like the Botox has "kicked in" as the muscle is not as prominent when you clench your teeth. Good luck, Dr. M

since the masseter is such a  large muscle it takes longer to have an effect usually 3-4 weeks. the dose used was pretty small but i do not know the size and thickness of your muscle. a second treatment might be necessary

I do not think that the muscle thins out too much after the first treatment. I tell patients repeated use every 3-4 months will eventually thin it out a bit. It is not a "one and done" procedure.

Botox functions to relax the muscle.   For most individuals, 6 months is usually necessary before a reduction in muscle size is noticed.  

By two weeks after the injection you could feel the muscle soften when you bite down- it is less bulky and weaker. To notice a reduction in muscle size from inspection alone, it could take 1-2 months. The dose was definitely enough for the first time. Be well.