Hydroquinone after PIH on labia from Brazilian laser hair removal - will it resolve the issue permanently?

Hi, I had laser hair removal on my Brazilian around 3 months ago. I've had this procedure for years and had never had any issues - however this time the technician asked if I could feel it and I said no - so she turned it up. After my whole outer labia was a dark brown (instead of the pale colour it used to be). My DR advised it was PIH and prescribed Hydroquinone 4%. How long will this take to work and will it resolve the issue permanently? Can I ever get this procedure again? Thank you!