How Long Does Botox in the Masseter Muscle/jawline Really Last?

Thanks for the question. This is one of my favorite uses of Botox, as I've been able to help hundreds of patients overcome their severe TMJ pain and teeth grinding. Additionally, many female patients receive masseter Botox to narrow the jawline, creating a thinner look to the lower face. In general, the Botox begins to wear off around 3-4 months later, but many patients don't feel the need for another treatment until 6-12 months post-treatment. This is because the muscles remain a bit smaller and softer, and many patients are able to break the habit of grinding their teeth. If patients return on the earlier side, I can often achieve the same results with fewer units. Best regards,Dr. Mehta

You actually had a smaller dose for this area and indication.  Your botox should last between 2 and 4 months with an average of 3 months.

You should expect to see results in three to four days, but in as few as two and as many as five days. On average patients return every three to six months for additional treatments. Good luck.

The good news is that botox always wears away.  The stronger the dose, the longer it lasts.  In my patients, the initial botox treatment lasts from 3-6 months in the masseter area.  As you continue to have botox in the area, you will likely notice that the duration of effects lasts longer (6-9 months).  I believe that this is due to chronic underuse of the muscle.You will notice that your ability to clench your teeth returns first, and then the masseter will grow back again.  If this is your first treatment, your face should return fully to its original shape.  

There was a good study out of Asia looking at this and yes it does tend to last longer than in the facial muscles but probably no longer than 6 months.  Certainly not permanent.  The more times you do it, the more the muscles atrophy and yes, in that same study, if you did it for 5 years the muscles would permanently stay smaller but again, this is only after repeated treatments with no breaks over many years.