The injection is called Program. It wont kill eggs, it only causes fleas to stop producing hatchable eggs. (at the vet we called it "birth control for fleas")

That's a good point. If he's allergic to the Advantage/Frontline/Revolution products, I wonder if he's allergic to the injection too? I'd ask the vet, that's important.

I agree with Gary, you may have to flea bomb your house too. Ick, fleas are horrible! Not fun....