Safe to use flea collar after drops not too long ago?

I had gotten a cat that was treated with zodiac drops (methoprene) about a week or two ago, and it didnt work well. I used the hartz flea collar hesitantly and it hasnt done much for the fleas yet.

I'm worried about an adverse reaction.

I have only heard terrible things about the over the counter products.
They also dont kill the eggs.
If you go to a vet they can provide you with the appropriate product that wont be harmful to your pet.
Good Luck:thumbs up

I'm with Winston, not a big fan of those collars and a vet visit is best.