WebMD describes creatine as a substance that helps to make adenosine triphosphate, or ATP, which provides the body energy for muscle contractions. Although it is made naturally in the body, it is also available through meat, fish and various athletic supplements to enhance physical performance. Creatine works by pulling water into the muscles, increasing protein synthesis. Studies have demonstrated that when combined with exercise, creatine causes muscle fibers to grow.
Brittany Risher for Men's Health writes that creatine is considered safe to use. Evidence points to creatine aiding in short periods of physical activity, but it appears to have little effect for endurance athletes.
WebMD warns that although risk of side effects is rare, excess dosing can lead to weight gain, cramping, diarrhea, headaches and kidney problems. The latter is particularly concerning to health care professionals, who do not recommend that people with kidney or liver disease take creatine. Certain drugs like caffeine and other stimulants can increase the risk of experiencing these negative side effects. Creatine should always be taken with plenty of water to prevent dehydration.
Despite its popularity, Risher does not suggest people take creatine unless they truly need it, especially children under 18. Creatine can cause people to overexert themselves, tearing their muscles which can lead to permanent damage.