Are there any side effects from lip corner fillers?

Because the corners of my mouth droop, I look just like an angry person when I have a blank expression.

I really hate that and it's stressful.

I also hate it when people around me keep asking if I'm angry.

I noticed that even a slight turn of the corners of the mouth can drastically change one's impression.

Are there any specific side effects to lip corner fillers?

I'm getting interested in lip corner fillers...!!