Why are there more fleas after applying flea medication to my cat?

[Nicholas1302]

My cat was scratching herself a lot, so i took her to the vet. They found flea dirt on her, and gave me some flea meds. I applied it when we got home. Like an 30 mins to an hour later, I was playing games while she was sitting in my lap, and I kept feeling a crawling sensation on my face. I rubbed my face, and there were fleas all over me. Does that mean the medication is working?

[Jersey2]

They will all be dead tomorrow:

From AI:

Why Fleas Become More Active Initially
Many common flea treatments (especially topical spot-on products like those containing fipronil, found in brands such as Frontline) work by overstimulating the fleas' nervous system. This causes hyperexcitation or hyperactivity in the fleas before they die. As a result:
- Fleas may jump around more vigorously.
- They often rise to the top of your cat's fur, making them easier to spot.
- This increased activity can make it seem like there are more fleas or that the treatment isn't working—when in reality, it's a sign the product is taking effect.