I am quite insecure about the size of my trapezius muscle and also my short neck. I have read that this procedure is able to reduce that. Are there any bad side effects to doing this?
You absolutely can have it for aesthetic reasons, ie to make the neck look more elongated.
The side effects are the typical ones, which include bruising, swelling. Also multiple treatments may be required to slim it to the amount that you want.The rarer ones include infection etc. Also, for those who need their trapezius strength eg professional athletes, we wouldn’t recommend it due to the potential weakening of the muscle.
I will write a post about this treatment for you soon, which will give you more detail than above