Energy is created by converting ADP→ ATP which is the energy currency for muscular contraction. Creatine aids this process therefore creates more energy for contraction and recovery of muscles.
Creatine should be taken in a loading phase and then a maintenance phase. Most effective pre and post workout to assists muscles with growth and repair.
Typical side effects of doping include: dehydration, muscle cramps etc, But can be prevented with regular and controlled intake.

Fig 8. Graph to show creatine maintenance and loading phases