Experiences with meds for behaviour

Hello!

My BC is 3 years old and still shows signs of reactivity (she cannot have a dog within 30 ft of her or she barks and lunges); it takes her a couple hours to fully come down from an incident. We have been working with fear free/R+behaviourists and trainers since she was 6 months old. We know that she’s the nervous type and has sound sensitivities as well. While she’s made excellent progress in the past little while of dedicated work, I am considering drugs once I rule out any underlying pain. I do have a few questions and was looking for some opinions/experiences:

Has anyone had any experience with behavioural modification meds? If so, what kind?

How long was your pup on them for?

Were there any side effects?

Was there any veterinary monitoring required?

This sounds a bit silly but I suppose I’m a little scared that I might be covering up another condition with these or I might somehow cause organ damage and shorten her lifespan or something.

Thank you for reading and looking forward to your responses.