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

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.

Hello and thank you for your question.  Treatment dosage for large masseters vary from one person to the next, however, it can normally require 20-30 units per side. On examination I determine the amount of Botox needed by placing my hands on the patients face while having them clench using their back teeth.  This gives me a good indication of how strong their muscles are, and how much Botox they can handle, without compromising normal and necessary usage of the muscles.  After your treatment there is usually minimal swelling, some around each injection site, and some from the fluid (Botox) that is injected and is waiting to be absorbed by the muscle.  This swelling doesn't last more than a day, and usually goes unnoticed.  There is also a chance of bruising, although less likely with Botox than with fillers, but taking proper precautions can minimize this risk.  Avoiding blood thinners and alcohol 5 days before your injections can help reduce your risk.  Taking Arnica starting the day before and continuing the day of can also aid in the healing process. I advise that you seek an experienced injector who specializes in facial aesthetics and has experience treating masseter hypertrophy or TMJ for best results.  Good luck!

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).

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.

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, FACSDenver Facial Plastic Surgeon

Thank you for your question. There are different techniques and doses used to treat the masseter. Typically 40 - 50 units of Botox on each side is injected to achieve slimming results. Best,  

Hi Irsi,
Thank you for your question!
Treating the masseter muscles with Botox or Dysport is a great option for you if you are looking to improve facial shape. This treatment can give a square face shape more of a "V"-line shape, along with accentuating cheekbones and creating a better defined jawline. 
Botox to the masseters does not typically result in much swelling, however there is the risk that the Botox can affect a neighboring muscle altering your smile. To best avoid this it is important that injections are kept lower and farther back in the muscle, away from muscles involved in smiling. Treatment dose really depends on the strength of your masseter muscles, an average dose can range from 20-30 units of Botox per side. 
Be sure to see an injector with extensive knowledge of facial anatomy. I've created a video that reviews treating the masseter muscles with Botox or Dysport. I hope you find this helpful in your research!

Thank you for your question irsi. I understand your concern. Botox is a purified protein used to address wrinkles associated with facial expression. When injected into the skin Botox will relax the muscles and smoothen out the overlying wrinkles. The most common areas of treatment are in the upper face. These include the horizontal lines seen on the upper forehead when one raises the brows, the vertical lines seen between the brows when one frowns (frown lines), and the crow's feet seen around the eyes when one smiles.It is difficult to make an assessment without a formal exam in the office where I can view the skin in multiple angles and observe wrinkles formed with facial expression. However, I hope the information provided here is useful.Botox can be placed in the masseter muscle in the lower face to contour the lower face and address pain associated with TMJ. In this area 20-40 units of Botox are used per side. Depending on the reason for the enlargement of the muscle, permanent results may be achieved. For example, some people have a habit of grinding, clenching, or biting their teeth subconsciously. Often times this happens in their sleep when they are not aware of it. Botox placed in this muscle will relax the muscle and the grinding, clenching, and/or biting will decrease. This will reduce the size of the muscle. If the brain gets accustomed to this and the person stops grinding, clenching, or biting, then the muscle will not become enlarged or as enlarged again. However, if the habit starts again, the muscle will likely get larger.With any injection, there are risks such as pain, bleeding, bruising, redness, swelling, tenderness, and infection. We take special precautions to minimize these risks such as using a painless technique. We also treat bruises with a laser as early as the next day. Bruises usually resolve within two weeks if untreated. After a laser treatment bruises usually resolve in 1-3 days, but may still take two weeks for full resolution. In addition to these risks, with Botox there is also a risk that the product spreads or diffuses to nearby structures. Spread to nearby muscles can lead to side effects such as the temporary appearance of droopy eyelids or a temporary asymmetric smile.After a Botox treatment, I recommend that my patients avoid heat exposure, alcohol consumption, and strenuous exercise for 24 hours and not lie down flat for four hours. This is because all of these activities may possibly lead to the movement of the product and consequent side effects such as droopy eyelids as described above. Although there have been no definitive studies shown that these actually occur and some physicians do not provide such aftercare instructions, in the absence of data I err on the side of caution and recommend that my patients avoid such activities.Please consult with a doctor for specific recommendations. Good luck!

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

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.