I used the Hartz flea body spray. My cat couldn’t eat for a week, gagged alot and slept more. It was only on her for 10 minutes before I knew something was wrong. Didn’t kill the fleas. I didn’t want her to be covered in sores from fleas so a few weeks later I got a flea collar thinking it was safe because she couldn’t lick it. She still had fleas but acted fine. She was great, but went missing 7 days ago. Not like her. She most likely found a quiet place to pass away.
I don’t know for certain that these products killed her but my point is that you should find a natural product or risk living with the guilt that you potentially poisoned and killed a otherwise healthy animal.