What Is The Main Ingredient In The Flea Shots For Dogs? After My Dog Got His Shot My Allergies Have Been Bad?

There are no “shots” for fleas that I know of. Your DIL needs to give you the EXACT NAME and manufacturer’s name of the product, so you can contact them and ask THEM what’s in their product.
There’s no way WE can tell you since we don’t know the product.
YOu also need to show this to your doctor and discuss it… not with the helpful, but not as fully educated masses at YA. -!-