Creatine is an important part of energy stores in your muscles. It helps provide rapid energy for muscle contraction. Body builders believe that creatine supplementation improves performance in muscular strength activities. They also believe it augments short bursts of muscular endurance and lets them train at higher intensity to increase muscle size and strength.
Most of the research indicates short-term power performance benefits with creatine supplementation (20–25 grams daily). Some increase in body weight has also been reported. Whether this gain is due to bigger muscles or water retention has yet to be determined.
One negative side effect reported from short-term use is water retention. No long-term evaluations (beyond 12 weeks) have been published, so there is no information on long-term side effects.