What are some side effects of taking "legal" steroids such as deca-alt, tren-alt, etc?

I was looking into finding a way to get big fast, and as usual, steroids popped into the picture. I'm way too afraid of needles and the side effects of taking actual steroids. I was wondering if the alternatives to steroids pose the same risks? If not, do they show up in steroid tests? And how good do they actually work?