By Mayo Clinic Staff

Creatine is a compound that comes from three amino acids, which are the building blocks of protein. Most of the creatine in your body is stored in your muscles, and smaller amounts are stored in your brain. Most creatine supplements use a form called creatine monohydrate. The liver, kidneys and pancreas also naturally make creatine. People usually get creatine through seafood and red meat. A typical diet gives about 1 to 2 grams of creatine a day, and the body replaces about 1 to 3 grams a day to keep usual creatine stores.

Your body mainly stores creatine in muscle. Much of this creatine is held in a form called phosphocreatine. This type of creatine is used to make energy quickly during short activity bursts. Many people take creatine supplements to improve athletic performance and to increase muscle mass when combined with resistance training.

Researchers also study creatine to see how it may help some brain conditions and nervous system and muscular conditions.

Research on creatine supplement use for specific activities and conditions shows:

• Strength, muscle size and performance. Creatine supplement use might help an athlete do more work during repeated short bursts of high-intensity exercise, such as lifting weights or sprinting. Creatine supplements, especially when combined with resistance training, can lead to greater gains in muscle strength, muscle size and athletic performance.
• Injury prevention and recovery. Research does not show a higher risk of muscle cramps or muscle injury in people who take creatine supplements. Some studies suggest that creatine may support injury prevention and rehabilitation in athletes, but more research is needed.
• Rare creatine-metabolizing syndromes. In children with certain creatine deficiency syndromes, creatine supplements might improve some symptoms.
• Memory and brain health. Some early research suggests that creatine supplements might improve memory and thinking skills, especially in older adults. More research is needed.
• Strength and bone health in older adults. Older adults who take creatine supplements and do resistance exercises can improve strength. Research does not show a clear benefit for total bone mineral density.
• Heart failure. Evidence is limited and it's unclear whether creatine supplements help treat heart failure.

People with low levels of creatine, such as vegetarians, may see more benefits from creatine supplements and larger increases in muscle creatine stores.

Creatine might help athletes who need to use short bursts of speed or increased muscle strength, such as sprinters, weightlifters and team sport athletes.

While taking creatine might not help the performance of all athletes, evidence suggests that it is safe when taken as directed.

Some older reports have suggested that creatine might worsen kidney function in people who already have kidney conditions. But studies in healthy people who take creatine haven't found that creatine harms kidney function when taken at recommended doses.

When taken by mouth at recommended doses, creatine is likely safe for many people to take for up to five years. As with any dietary supplement, it's important to choose a product that follows recommended manufacturing practices and uses third-party testing to make sure the product is high quality.

Creatine can cause side effects such as:

• Weight gain.

Research on creatine use in people with kidney disease is limited. People with kidney disease may want to talk with their healthcare teams before using creatine.

Possible interactions include:

• Caffeine. Taking caffeine and creatine together might reduce how well creatine works, but more research is needed. In one large study of people with Parkinson's disease who took creatine, those who consumed more than 300 mg of caffeine a day had faster progression of Parkinson's disease. More research is needed.

When used orally at appropriate doses, creatine is likely safe to take for up to five years. As with any dietary supplement, it's important to choose a product that follows recommended manufacturing practices and subscribes to third-party testing to ensure the product's quality.

Creatine can cause:

• Weight gain, generally as lean body mass

Creatine might be unsafe for people with preexisting kidney problems. However, further research is needed.