The gal at Home Depot said this worked for her. I bought this not for a clogged drain but another problem: drain flies. These flies live in the muck in my shower drain. Never heard of them? Me neither.
I couldn't wait for the mail order drain fly killer, so I used this green gobbler.
It made the house smell like sewage. I thought the smell was from the muck it was destroying but now I learned that the smell is the product itself. I didn't really care though. It went away.
However, I haven't seen anymore drain flies. So for me, I didn't have to call an exterminator and I am okay with this product.
Bottom Line: No, I would not recommend this to a friend