You may have to play w/the dosage for a while until you get it adjusted. Also, I give it to my Fur Posse only at night. They don't get drowsy; they just chill out. I hear them playing during the night, etc. They get 1/4 of a 20 mg. tablet and that does the trick. It sometimes takes a while for it to begin working but it worked immediately for my cats. Check the dosage and if it's higher than 5 mg., talk to your vet about lowering the dosage. It's been a godsend for me. Good luck and let us know how you make out.