Evidently this post was started in 2011 it’s now 2019 and people like me are still having to learn this horrible lesson the hard way. I bought sergeants flea drops and used on my 5 month old kittens. Well that night they seemed to be more hyperactive than normal at the time I didn’t realize that was the first symptom of a far worse reaction that all three kitties would have. First my Tigger got real lethargic. He wouldn’t eat or drink I had to use a large syringe to get water down him. It looked really bleak but somehow I nursed him through it. Then Micky starts in not eating and drinking. He ended up being the sickest. I actually bathed him even though it had been several days since I put the drops on them. Finally he started improving then the girl kitten seemed to have trouble walking and I couldn’t do nothing but cokes her into walking and gave her massages. It to a couple of weeks to get them back to normal. The worse part was they was so lethargic.