It's time to treat kitty for fleas (poor thing, I found a couple during her last brushing), and I've got a couple of tubes of Advantage -trouble is I don't know how old they are (probably over a year, since I don't remember buying them any time recently). There is no expiration date. Does it go bad?

I don't think there should be any harm in using it. They don't have an expiration date on their packaging at all, only a lot number. If you are concerned, you might call Bayer and ask about that particular lot. Otherwise, I would think the worst case is that the medicine is slightly less effective, but it may be that there is no difference.

I've used year old flea meds before without a problem.. we often bought it at the beginning of the warmer season and had a couple left over we saved until the next year. So it should be fine.

I think I remember reading somewhere that the insecticide used has a shelf life of 5 years, if stored properly.


Hmm... I find it rather interesting that imidacloprid acts on insects acetylcholine receptors...

Thank you for your advice. I decided to apply the Advantage I had on hand, and while the fleas aren't -gone- yet they are definitely fewer. I'll see how she looks in a day or so. -Again thanks.

I actually called the company with the same question. I had an old Advantage (3 years). They said as long as the ampule is intact, that it should be fine.

I have some Advantage in a drawer somewhere and it had an expiration date on it. It said 08/2009 underneath the lot number. It must have been purchased in 2006 btw, because I used Revolution last summer.