What are the side effects to masseter reduction with Botox, and how long does the swelling last?

I would like to try slimming a square, heavy jawline through Botox injections with either a dermatologist or a surgeon. How many units are considered moderate for a medium-sized female jaw, how long does swelling last, and what a precautions to take before choosing this procedure?

Doctor Answers 11

Masseter reduction with Botox - dosage and side effects

For a medium-sized female jaw, I typically use 15-20 units per side.  If the muscles are large, I will use up to 30 units per side for a female.  Men sometimes require as much as 50 units per side, since they have much more bulk.

The worst, unwanted side effect is alteration of the smile.  This happens if the injection is placed too high or too anteriorly.  This can result in undesired weakening of the muscles that pull back/elevate the angle of the mouth during smiling.  

Other side effects include 1) the face becoming too slim, 2) the jowls appearing more prominent because the back of the face is less bulky.

There is not typically any swelling with the botox injection, unless a bruise forms.  If a bruise forms, this may take a few days to go away.

One other caveat is that if the "square jawline" is due to an angular jawbone, botox will not change the shape of the jawbone.  It only softens and shrinks the masseter muscle.

Houston Dermatologic Surgeon
5.0 out of 5 stars 12 reviews


Botox can be injected in masseter muscles that are hypertrophied from teeth clenching or habits that involve prolonged chewing, or to balance an overly square face.  I usually start with 24 units per side in women, but would use less for smaller-faced women. The effect typically lasts 3 months, but sometimes up to 6.  As the treatments are repeated, the muscle continues to become even  smaller.

There are no precautions to take before treatment other than to be certain one is not pregnant, and no swelling occurs with treatment.

I would be happy to answer any additional questions you might have.

All the best, Dr. Clark

Sheryl D. Clark, MD
New York Dermatologist
5.0 out of 5 stars 8 reviews

Important considerations during Botox for masseter reduction

The most important "precaution" to take when undergoing Botox for masseter reduction is to do your homework in finding a qualified physician to perform the treatment.  

A typical "moderate" dose is 50 units, or 25 units of Botox on each side.  Immediately after the procedure there typically is not any discernible difference, as the masseter muscle is so bulky to begin with that the volume of Botox does not make a huge visual difference.  

With an experienced physician the main possible side effects are bruising (<5% of patients) and you may notice you become tired sooner when chewing excessively (all day gum chewing or 22 oz steak etc).

Donald B. Yoo, MD
Beverly Hills Facial Plastic Surgeon
4.9 out of 5 stars 58 reviews

Masseter Reduction

Using Botox or one of the neuromodulators in the masseter can be an excellent way of slimming the face. It also can help with jaw clenching. It needs to be performed by a specialist who is comfortable with experience in treating this area because the number of units will depend on how much improvement you get. Generally, 20 to 30 units are injected depending on the size of the masseter and the level of improvement desired. I have found that over time, the masseter will actually atrophy and sometimes can last as long as 6 months, longer than some of the other aesthetic Botox injections. My patients who get masseter injections are able to get them just twice a year, whereas we do some of the other facial injections more often. As with anything, over time, the muscles tend to be retrained, and tend to need less product and injections less often. For young women, especially Asian women sometimes, we treat at an early age, which actually can cause some permanent improvement in the face. And there has been some studies that show reduction in the actual jaw size after repeated injections into the masseter. So seek out an expert in this area and discuss with them the results that you can get. Best of luck.

Joseph A. Eviatar, MD, FACS
New York Oculoplastic Surgeon
4.7 out of 5 stars 66 reviews

Botox injection of the masseter muscle

Botox injections are a great way to treat the masseter muscle to induce's limiting of the lower face.  As long as the drug is placed in the proper location the likelihood of side effects is extremely low.  It can take high doses of Botox to achieve the desired outcomes but patient's satisfaction is very high following this treatment.

Brian Biesman, MD
Nashville Oculoplastic Surgeon
4.8 out of 5 stars 41 reviews

Side effects of #Botox #masseter #reduction

Botox masseter reduction has few side effects. A very small needle is used to inject about 50 units of Botox ($600 cost) total. This does not create any noticeable swelling in most cases. The results last about 4-6 months or longer. I hope this information is helpful for you.

Stephen Weber MD, FACS
Denver Facial Plastic Surgeon

Stephen Weber, MD, FACS
Denver Facial Plastic Surgeon
4.9 out of 5 stars 129 reviews

Botox for Masseter Muscle

it typically takes 20 units on each side to treat the Masseter muscle. There should be no swelling. With continued treatments every 4 to 6 months you will see improvement and more facial slimming. Best, Dr. Green

Michele S. Green, MD
New York Dermatologist
5.0 out of 5 stars 78 reviews

#botox for masseter reduction or facial sliming is a safe and effective procedure

Typically the number of units used depends on the muscle mass of the masseter. On average it is 50 - 60 units for medium jaw line reduction. The doses can range upto 100 units in bulkier massters as seen in Asian faces.
usually it is 3 - 5 points per side for the injection with the doses disturbed among these points. The procedure is quick. Effects are seen 3 - 4 weeks after the procedure and at 6 weeks you will notice the full effect after your first procedure.
This procedure will help reduce the bulkinessor heaviness of the jaw line and achieve a slimming effect.
Subsequently you may require lesser units if you have the procedure related at regular interval of 4 months in the initial1 year and post that the interval between sessions can be longer.

Swelling or bruising post this injection is rare. 
In case of swelling, it settles typically within 72 hrs

Chytra Anand, MBBS, MSc, DD
India Dermatologic Surgeon

Masseter and botox

The masseter hypertrophy can be treated using Botox. Often it takes bout 40-50 units in multiple small injections. It can take a series of injections over a 6 month period to a year to see the desired effect.  It is not immediate.

Steven Wallach, MD
New York Plastic Surgeon
4.1 out of 5 stars 29 reviews

Masseter injection.

Botox works well for decreasing the full, heavy master muscle. A typical dose is about 40 -50 units per side.
Good Luck

Stephen M. Davis, MD, FACS
Green Hills Plastic Surgery

Stephen M. Davis, MD, FACS
Nashville Plastic Surgeon
4.8 out of 5 stars 24 reviews

These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.