Stacy, my NAC is Designs for Health brand.:)

IMO, no. FWIW, We've used several brands (whatever's least expensive when we order) and found no difference.

Doc

There was an article in the Consumer Reports that store brands are just as good as the branded products.

Sally, in my research of NAC I found this:

Secondly, I advise against using NAC if you still have mercury amalgam fillings because it could interfere with the detoxification of the mercury. Dr. Mercola

I do have mercury amalgam fillings.

Do you worry about this?

No, I don't worry. I have taken Alpha Lipoic acid and NAC for a few years now. You can ask your doctor if you have an integrative Md and see what he says. I take Glutathione by Liv On Labs also.