Cat's flea collar trouble!?

flea collars are dangerous. they can poison yo cat. mine died cause of all the chemicals they used in that stuf and my cousin's nose swelled up like a watermelon for like three weeks. so the doc told us to use advantage or something. that drop on the neck stuff works way better, i hav'net seen a flea for like ever since we used it on my cousin, i mean my new other cats...