Anyone had a paradox reaction to a sedative?

[SchoolMarks]

DS is going to have to have a sedative next week for a minor procedure. I've been warned that as he has asd/adhd he has a higher risk of having a paradox reaction, although we won't know until he takes it. It was a bit strained appointment today (refusal to cooperate!) and I forgot to ask what would happen if he does. Is it a case of waiting until it passes? And will it last the length of time the sedative is supposed to last?

DS (AS/ADD) had to have a milk tooth removed whose root didn't resolve properly while the adult teeth were already there.
He got the sedative and we waited for him to calm down, which simply didn't happen. He became more alert with every minute and in the end the dentist removed the tooth without sedation. As his pain threshold is different, too, it turned out not to be a problem.

DD has a delayed reaction - she got the sedative, nothing happened, she had the procedure done without. As we wanted to leave the sedative started to act. DH spent 1h in the waiting room while DD slept like a log.