Can masseter Botox cause permanent changes? I have lost all definition in my jaw. (photo)

Given time, the Botox effects should reverse themselves.  Be patient and allow six months while not doing any further Botox and see if your jawline's definition improves.The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice.  The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs. 

Typically Botox lasts up to 4 months. Duration of effect is typically related to the dosage used and the baseline strength of the muscles being treated.  My best recommendation is to schedule a follow-up with a board-certified dermatologist so they can assess your results in-person!

Thank you for your question and photo sophiac006. Injecting Botox into the masseter muscle weakens it, and over time while the muscle is weaker it atrophies (decreases in size), providing the slimming effect. The effects of Botox to the masseter muscle last an average of 4-6 months. Once the effects wear off, the muscle will begin to function more frequently and regain its strength, slowly increasing in size again. How quickly it regains it's strength and size varies patient to patient and also depends on the dose of Botox injected. 
I've created a video where I review treating the masseter muscles with Botox, I hope this helps in your research! 

It appears that you have received too much Botox in this area and didn't need this amount or placement.  I would just discontinue Botox and you should come back to normal after some time.  I would post before and after photos as well to help you.  Best, Dr. Green

The beffefts of Botox are temporary. The effect on the masseter or any other muscle is that it paralyzes or weakens the muscle temporarily which causes muscle atrophy (meaning muscle shrinkage). Your lower face and jaw angle are primarily determined by your lower jaw shape and the size of your masseter muscle. So, if you shrink the masseter as above mentioned you will loose definition. The good news is, all you have to do is to stop getting the Botox injections and after about 1 year or so the shape should return to its original size. You could also help it by chewing gum which “excercises” The muscle and make it grow bigger faster. Kind of like going to the gym!
Hope this explanation helped!
Best,
Dr. Hamrah

Botox is 100% not permanent. If you want to regain your jaw muscle you simply need to stop getting the injections and it will regain bulk and strength. It will take awhile for it to do this, but Botox is not permanent so it will go away. "This answer has been solicited without seeing this patient and cannot be held as true medical advice, but only opinion. Seek in-person treatment with a trained medical professional for appropriate care."