With the 600mg guailfensin or the Mucinex you have to drink a lot of water so it may work fast.

Thanks, yes, I've been able to get 400 mg fast acting, but it's not the same, I'm told, as the extended release. Still unable to get it. Walgreens looked like a possibility, but they've discontinued it!

I had tried a nearby Walgreens and they didn't have it. But thanks so much for your reply! Now that I know the name that they package the medicine under, it might be easier to find somewhere. Here's hoping. Thanks again!

I found that Walgreens is supposed to carry their own version that is comparable to the Mucinex brand. https://www.drugs.com/otc/122138/mucus-relief-e...

I really hope you have a Walgreens near you that has it in-stock!