Is it safe to use expired Gly Oxide?

I've had strep throat since Saturday and I'm just now getting rid of it but the medication they gave me is causing sores on my mouth, which is one of the side effects, but I looked online to see how to help it heal and it says rinse with Gly Oxide. So I found some in my room that has never been used and it expired July of 2009. So is it ok to use it still?