Botox on masseter muscle and wider mouth. Any suggestions?

I am planning on having botox injected for my left master muscle (it is more developed than my right master muscle, causing facial asymmetry and difficulty opening my mouth wider) and I am curious if the muscle is reduced enough should I be able to open my mouth wider?

Doctor Answers 9

Botox is a great choice to reduce the size of an overdeveloped masseter muscle in the right candidate.

Botox is a great choice to reduce the size of an overdeveloped masseter muscle in the right candidate. If the tightness of the muscle is what is causing your difficulty in opening your mouth, then relaxing the muscle should help with this problem. Discuss your concerns with your doctor to see if Botox for the masseter is the most appropriate treatment for this problem.

San Diego Dermatologic Surgeon
4.9 out of 5 stars 25 reviews

Botox, Masseter muscle injection, and mouth opening

Botox in select patients, can decrease the size of one or both masseter muscles to make the jaw appear smaller.

Changing the amount of mouth opening is a more complex issue based on the reason your jaw opening is limited. There are 4 major muscles that affect jaw position by opening (lateral pterygoid)  and closing it (masseter, temporalis, and medial pterygoid). In addition there are minor muscle groups that contribute. The temporomandibular joint  or TMJ may have arthritis-like issues that affect jaw opening. It could be any of the muscles or the joint or both. Some oral surgeons specialize their whole career on just this area. 

I would consider this a more advanced use of Botox due to the complex anatomy. Please seek out someone who performs this particularly technique a lot for the safest results. 

Victor Chung, MD
San Diego Facial Plastic Surgeon
5.0 out of 5 stars 10 reviews


Dear Julianhk:

if if a tight, chronically contracted masseter is the cause for your small mouth opening, relaxing it should help.

All the best,
Dr. Clark

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

Botox in massager and mouth shape

Botox should certainly decrease the size of your enlarged masseter and balance your face. It normally does not affect mouth size. In your case, it will only have an effect on your mouth opening if that is limited by your masseter tightness. You might want to have that assessed by a dentist, ENT, or oral or maxillofacial surgeon.

Nicole Kafka, MD
New York General Surgeon
1.0 out of 5 stars 1 review

Botox will help

Botox can be used to slim the appearance of the masseter muscle.
It should not improve opening of the mouth.

Keith Denkler, MD
Marin Plastic Surgeon
5.0 out of 5 stars 18 reviews

Botox for Masseter Muscles

Botox to this area should contour the jaw and not affect chewing.  Please see an expert.  Best, Dr. Emer.

Jason Emer, MD
Los Angeles Dermatologic Surgeon
4.8 out of 5 stars 190 reviews

Botox on masseter muscle and wider mouth. Any suggestions?

Thank you for your question.  Botox can be used to slim enlarged masseter muscles and if they are the source of your narrow mouth opening then treatment should improve it.  Hope this helps.

Nelson Castillo, MD
Atlanta Plastic Surgeon
4.9 out of 5 stars 65 reviews

Botox and Masseter Muscle

You should definitely be able to open your mouth after Botox is injected in the masseter muscle when injected properly.  Please consult an expert.  Best, Dr. Green

Michele S. Green, MD
New York Dermatologist
5.0 out of 5 stars 76 reviews


It depends upon what's causing the difficulty in opening your mouth.  Botox injected into the masseter muscle will weaken the muscle.   The masseter is one of three paired muscles that causes you to close your mouth.  In addition to tight muscles, there might be other reasons why you have difficulty opening your mouth, such as TMJ issues.  Before proceeding with the botox injection, I would suggest a consultation with a good oral surgeon to see if the TMJ is involved.  Best of luck. 

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.