Are lethargy and sleepiness side effects of Advantage?

Our question this week was:

I have a 13-week-old sheltie puppy. Yesterday I bought some Advantage for puppies 7 weeks and older and under 10 pounds (he weighs 7 1/2 pounds). I put it on him between the shoulder blades and within about 10 to 15 minutes, he got very sleepy and lethargic. I took him to the ER vet and he told me to wash it off with dish detergent, which I did. He bounced right back and seems fine now. I looked on the Internet for side effects for Advantage but lethargy/sleepiness was not one of them. I am wondering what could have caused this reaction in my puppy and are there any other products such as Frontline that would be safe for him?

Thanks so much. I love your newsletter!

Jill Smyly


Hi Jill – thanks for your email. I have not seen side effects of lethargy and sleepiness with application of Advantage.

The most common side effects from Advantage that I've heard is drooling if it is licked off. From what I read, overdose is rare and no adverse effects have been reported at even up to 5 times the recommended dose.

It sounds pretty suspicious that your dog did have a reaction do Advantage. I would have done and recommended the same thing as your vet as far as wash it off.

I like advantage but have not had a problem with it. However, if what happened to you had happened to me, I'd probably try something different next time. For some ideas on what to use, this article might be helpful to you is Pour it on the Fleas.

Best of luck!

Dr. Debra

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