I'm thinking of using HA paste for my brow. It's tough when you hear different opinions. My advice is to ask direct probing questions and ask for some type of proof to back it up.
When I was consulting for LF3 I was told tons of horror facts about this procedure and even thrown out of some doctors offices. Heck one doc who does lf3 very often (possibly the most in the world) actually sent me back my letter and pics with NO!!!!!!!!! written all over the letter.
What me conformable with Dr. Sinn was everything he said he either backed up with a detailed why or I was able to verify what he said.
Example one doc told me lf3 has a huge risk of blindness. I asked dr. sinn ,dr. sinn said it doesn't and explained exactly why it doesn't with great detail. I went back to the other doc and asked why does it cause blindness and got a generic "anytime you cut around the eye its a big risk".
So my advice is asking y. If a doctor tells you it is an irritant, ask where can you see that it is either online, or ask for his explanation.