Reapplying Frontline Flea medication

I gave my cats a treatment of Frontline Plus flea medication about 3 weeks
ago. The cats are scratching again. Should I treat them again now? The instructions said to wait one month.

Are you seeing fleas again?Or could it be from dry skin?
I would call your Vet in the am and get their advice about it to be safe.
I was told not before every 4 weeks and if I could to space it out to every 5 weeks.I'm sure every Vet has their own opinion about it.

Cats scratch naturally. Even if they dont have fleas. Well mine do anyway. I would wait the full 4 weeks.

Wait a month....follow the directions for sure.. Sometimes old flea bites can probably still make them itchy I imagine.

Give your cats a medicated shampoo bath now, it may be dry skin - not too strong, dilute the shampoo well and rinse lots and rinse again. I would wait for four weeks for frontline, it's efficacy does not wear off if you bathe them.