My lawn gets fertilized every month. is this bad for my dog?

Hi. Every month my lawn gets fertilozed and people say its bad to let your dog to play on the lawn right when it was fertilized. Of course, i didnt let my dog get near it. If my lawn is fertilized, how ling should i wait til i can let him on my lawn safely? If my dog does geg sick from it, what are some signs that he is in danger of this?