Are There Any Side Effects Of Taking Dianabol?

I am 16 years old and I am thinking about taking steroids its called dianobol and it is a bottle with 90 capsules for 3 months you take 1 every day but I am going to only take it for 1 month so 30 days only and my other 2 cuzins are doing the same its 25 m would anything serious happen to me if i only take it for 1 month