I wish that I had researched this flea medicine before I used on my cat. I have always used another medicine but was out and picked up Sergeants because my usual store that I purchase my flea medicine was closed. Within hours my cat was vomiting, tremors and lethargic. Took him to the vet and the flea meds were washed off but not before the damage was already done. The vet said after the blood work and x-rays that all signs pointed to the flea medication. Walter was strictly and indoor cat and that is the only thing that could have caused his poisoning. My cat was not so lucky and passed away. I too along with others can not understand why this product is still on the shelves. My cat was 4 yrs old with no health issues, he had plenty of life left only to suffer due to a flea medication.