Meanwhile, Clenbuterol is not actually a steroid. Rather, this is a substance that increase the amount of oxygen that can get around the body. In turn, this then increases the amount of fat being burned as well as enhancing energy in the gym. On top of this, Clenbuterol is also a mild stimulant, which increases the metabolism. Clenbuterol can be dangerous in the long term and may cause heart problems in particular. In small doses though, there is less to worry about and there is no chance of impaired testosterone production, impotence or other side effects associated with testosterone or steroids. It’s also relatively liver toxic.