Will it damage my toilet/drain if I use this drain cleaner?

I bought this drain cleaner because my toilet his plugged. But now that I read the back of it, it says "do not use in toilet bowl", but it also says it wont harm pipes, porcelain and septic tanks. Should I try using it? I'd like to pour it into the toilet and let it sit while im sleeping, then flush when I wake up. the drains plugged with toilet paper since last morning