Botox for reduction of masseter. How many units are required for a noticeable difference?

Question

How many units is required for a noticeable difference? Or is it entirely dependent on the individual? I've visited a few clinics and I've been quoted either 15 or 25 units. I was told by one doctor that with Botox, only a small amount is needed for a difference to be seen. But some clinics recommended a higher dosage as the cost was paid for per unit. Could anyone provide some information on this and what dosage they recommend?

Young R. Cho, MD, PhD · Answer

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.  Once you stop using Botox, the masseter muscles will return to their original baseline when the effects of Botox  wears off completely.

Ava T. Shamban, MD · Answer

Everyone's facial anatomy and response to Botox differs
     and the masseter is no exception.  A good starting point is 15-25
     units and following up with your provider 2-3 weeks later to determine if
     more is needed.  Close follow-up is key to determine what amount is
     just right for you.  Once this is determined, then you can resume to
     a less frequent schedule of botox injections since touch-ups will likely
     not be needed for subsequent sessions.

Donald B. Yoo, MD, FACS · Answer

The appropriate dosage of Botox for masseter reduction is whatever dose will achieve full relaxation of the masseter muscle.  Just like any muscle, if it is incompletely relaxed then it will be able to contract and "exercise", and thus will not atrophy and shrink maximally.  For approximately 80% of patients, a dosage of 25 units per side (50 units total) will achieve full treatment.  I typically recommend patients to return 2-3 weeks after their initial treatment to determine if any additional Botox is necessary for full treatment.

Bryson G. Richards, MD · Answer

Thank you for your question.I use approximately 25 units per side because the vial comes in 50 units so I divide it between the two sides. I think only 15 is really needed though. You can always start with a less aggressive approach and up the units if needed.- Dr. Bryson Richards

Kristin M. Baird, MD · Answer

I would agree with the Botox unit range that was quoted to you. Typically, I place about 20 units into each masseter muscle for a total of 40 units. Certainly, this depends on the individual and some patients require even more units. I recommend consultation with a board certified dermatologist or plastic surgeon experienced in injection of the masseter muscle. Best wishes.

Calvin Lee, MD · Answer

An excellent question.  I've wondered this myself and I continue to wonder about what others think about jaw slimming with Botox.  The masseter is the main muscle which can give us a square-ish box-like face.I don't get this opportunity to do this procedure very much.  I've only had about 20 patients come in for this issue.   And about 16 patients who come in repeatedly for this feature of Botox at this time.  But I've had many more (probably 60 patients) who have had TMJ dysfunction/pain issues which required Botox in the Masseter muscle.My worst case scenario is a male patient who had TMJ pain which eventually resolved when we eventually came to the conclusion that 50 Units of Botox on each side helped.  I usually like to do my Botox procedures in a staged fashion where we do a little bit at a time and thus we eventually find the lowest dose that does the right job for us.  He did get jaw slimming features, but that actually was more evident after his third round of 50U of Botox on each side.  My experience with TMJ masseter muscle Botox helped me come to the realization that masseter/jaw muscle slimming Botox usually has it's most dramatic effect after the 3rd Botox treatment - assuming no large gaps between treatments.  So this is almost 10 months later.Thus for patients coming directly to me for Jaw slimming Botox (cosmetic only).  I try to assess how much of a "rush" patients are in for this to happen.  If they are OK with best results in 10 months.  I usually suggest about 16U-20U on each side to start.  And repeat this process in 3-4 months.  If a person is in a "rush" to get this result, I might start with a higher dose - such as 24-30U and then gradually lower this dose with each subsequent treatment - so I don't over-correct and get a sunken in jaw look - which in my opinion is not a youthful appearance at all.Summary:  Quick answer:  12-50 units per masseter muscle.  Long answer:  It's not the number of units per session - it might be the number of units done over time that matters most.  I've come to realize that the best appearances for masseter muscle slimming is obtained after repeated treatments to this area.  I tell my patients to be patient and wait for the appearance after the 3rd Botox treatment to the masseter area.  Everything in medicine should be individualized - especially Botox!My plastic surgery wife (Dr. Tammy Wu) says that this is very popular procedure in Asia.  She has several relatives in Asia who perform this procedure.Calvin Lee, MDModesto, CaliforniaThank you for your question. 
Without having seen you in person, I'm answering the best I can without
physical examination info.  My comments
are meant for a general public discussion to help others who may have similar
concerns.  I'm also using my answers to
build up library of information for my own patients and also to see how my
answers compare with other doctors. 
There is always much for us to learn from each other.  My answers are generalized medical
information only, not directed medical advice. 
For medical advice please see your doctor/surgeon in person.

Prashant Murugkar, MD · Answer

Hi, I can understand your confusion about the dose of botox required, each Plastic Surgeon will approach the issue with some variations but as you might have gathered from the answers below 15 - 25 Units per side is the range. there is always going to be a guessing game the first time you have the injections as your response to the Botox is not know to the PS, so its better to put a conservative dose and then check again at 2 - 4 weeks to see the need for a topup.hope this helps, do keep us postedwarm regardsDr Prashant

Steven F. Weiner, MD · Answer

I vary between 15-25 units per side, but can go up to 40. There have been several ppl on realself with bad results. Make sure you go to someone with experience.

Sean Doherty, MD, FACS · Answer

Thanks for the question. I typically inject 20-25units per side. Touching up after 2 weeks is always a good plan if necessary> Make sure you are injected by a qualified professional--this is certainly an advanced area for injection. Best of luck.

Botox for reduction of masseter. How many units are required for a noticeable difference?

Answers (9)

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