If the doctor does not have a solid grasp of the anatomical level, injecting botulinum toxin into the upper layer of the masseter muscle is likely to damage the facial nerve and cause abnormal stiffness. This situation usually includes drooling, crooked mouth and involuntary twitching of the corners of the mouth.

If there is any deviation in the injection position, it will cause abnormal facial expression, which will last for at least 8 weeks.

2. Too much is too late

When injecting botulinum toxin into bilateral masseter muscles, the total amount of each injection shall not be greater than 100 unit; The time interval between two injections should not be less than 1 month. If these two standards are exceeded, the facial expression will be stiff seriously.

3, postoperative care

Because if you massage the masseter muscle by hand after operation, the botulinum toxin that has entered the masseter muscle will penetrate into the adjacent expression muscle, resulting in unnatural expression. In this case, it takes at least 2 months for the expression to return to normal.