Consensus on Expired OPK's?

[heaveneats]

So I know this is probably a clear no no, but i had ordered Wondfo's on amazon last month, just got the new batch out and they expired in 9/2015 i've contacted the seller as they are listed as 'new' and no where does it say they are expired but i'm wondering if for some reason I can't exchange them how bad would it be for me to use them.... i have a feeling them being almost 2 years expired its would be a bad idea.

 

[jefnerf]

I was using expired ones last month and I managed to catch my surge... not sure what it is about them that would expire.