Here is a good overview from Harvard Medical on Creatine
Creatine
Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain creatine. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacist or health care provider before starting.
Evidence
Unproven Uses
Potential Dangers
Interactions
Dosing
Summary
Resources
Evidence
Scientists have studied creatine for the following health problems:
Enhanced muscle mass or strength
Some studies suggest that by increasing muscle storage of energy compounds, creatine may improve muscle mass and strength. Studies of creatine in athletes, however, have disagreed with each other. At the present time, it is believed that creatine may be useful for high-intensity, short-duration exercise, but it has not proven to be effective in endurance sports.
Enhanced athletic sprinting
Creatine has been suggested to enhance athletic performance during short sprints. Although results from different studies disagree with each other, most research shows some improvement when creatine is used as a supplement. Overall, creatine may enhance performance when used during brief bursts of aerobic activities, when there are short recovery times between bouts of activity.
Enhanced athletic endurance
It has been suggested that creatine may help improve athletic endurance. However, the results of research evaluating this claim are mixed. Results from different studies disagree with each other, although most studies do not support the use of creatine to enhance sustained aerobic activities.
Congestive heart failure (chronic)
Several studies have found that creatine is associated with improved heart muscle strength and endurance in patients with heart failure. However, it is not clear what dose may be safe or effective. Comparisons with drugs used to treat heart failure have not been conducted. Heart failure should be treated by a qualified a health care provider.
Heart attack
There is early evidence that intravenous creatine after a heart attack may be beneficial to heart muscle function. Further study is needed before a recommendation can be made.
Heart muscle protection during heart surgery
There is early evidence that heart muscle may recover better after open-heart surgery if intravenous creatinine, a form of creatine, is given during the operation. Further study is needed before a recommendation can be made.
Hyperornithinemia (high levels of ornithine in the blood)
Ornithine is a byproduct formed in the liver. Some individuals are born with a genetic disorder that prevents them from appropriately breaking down ornithine, and blood levels of ornithine become too high. High amounts of ornithine can lead to blindness, muscle weakness and reduced storage of creatine in muscles and the brain. Although there is only limited research in this area, early evidence suggests that creatine supplements may help replace missing creatine and slow vision loss.
Muscular dystrophy
Creatine loss is suspected to cause muscle weakness and breakdown in Duchenne muscular dystrophy. Animal studies show increased muscle formation and survival with creatine. Studies in humans have been small, although early evidence suggests that creatine may be beneficial in treating muscular dystrophies. Further research is needed.
Neuromuscular disorders
Numerous studies suggest that creatine may help treat many neuromuscular diseases. A few examples include amyotrophic lateral sclerosis (ALS) and myasthenia gravis. Although results in some of these early studies have been encouraging, additional studies are needed to provide clearer answers.
GAMT deficiency
Some individuals are born with a genetic disorder in which there is a deficiency of the enzyme guanidinoacetate methyltransferase (GAMT). A lack of this enzyme causes severe developmental delays and abnormal movement disorders. The condition is diagnosed by a lack of creatine in the brain. Although there is only limited research in this area, significant improvements were noted in two individuals who were given supplemental creatine, suggesting that this supplement may be an effective treatment for disorders caused by a lack of creatine.
High cholesterol
Although there is some research in this area, results from different studies disagree with each other, and it is not clear what effect creatine has on blood cholesterol levels. Larger studies are needed before a recommendation can be made.
McArdle's disease
In McArdle's disease, there is a deficiency of energy compounds stored in muscle. This leads to muscle fatigue, exercise intolerance and pain when exercising. Creatine has been proposed as a possible therapy for this condition. However, research has been limited, and the results of these studies disagree with each other. Therefore, it is unclear if creatine offers any benefits to patients with McArdle's disease.
Unproven Uses
Creatine has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care provider before taking creatine for any unproven use.
Breast cancer
Colon cancer
Diabetes
Herpes
Huntington's disease Parkinson's disease
Rheumatoid arthritis
Seizures caused by lack of oxygen to the brain
Wasting away of certain brain regions
Potential Dangers
Allergies
People should avoid creatine if they have a known allergy to this supplement. Signs of allergy may include rash, itching or shortness of breath. Creatine has been associated with asthma symptoms.
Side Effects
Some people may experience stomach discomfort, including diarrhea or nausea, and heat intolerance, leading to high fever, dehydration, reduced blood volume, electrolyte imbalances or seizures. Creatine may also cause muscle cramps, muscle breakdown, muscle tears, muscle pulls, weight gain and increased body mass. Athletes should be monitored by a qualified health care provider while using creatine supplements.
It is possible that creatine may alter liver function. Although there is less concern today than there used to be about possible kidney damage from creatine, there are some reports of kidney problems, and people with kidney disease should avoid use of this supplement. In theory, creatine may alter the activities of insulin and should be used carefully by those who take prescription drugs to control blood sugar levels.
Pregnancy And Breast-Feeding
Creatine cannot be recommended during pregnancy or breast-feeding because of a lack of scientific information.
Interactions
Interactions with drugs, herbs and other supplements have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care provider or pharmacist before using herbs or dietary supplements.
Interactions With Drugs
Use of creatine with probenecid may increase the levels of creatine in the body, leading to increased side effects. Use of creatine with diuretics such as hydrochlorothiazide or furosemide (Lasix) should be avoided because of the risks of dehydration and electrolyte disturbances. The likelihood of kidney damage may be greater when creatine is used with drugs that may damage the kidneys, such as trimethoprim, cimetidine (Tagamet), anti-inflammatory drugs such as ibuprofen (Advil, Motrin), cyclosporine (Neoral, Sandimmune), amikacin, gentamicin or tobramycin.
The activities and side effects of some cancer drugs may be enhanced by creatine supplements. It is possible that creatine may increase the cholesterol-lowering effects of other drugs commonly used to lower cholesterol levels, such as lovastatin (Mevacor). Animal studies have shown that the combination of creatine and some nonsteroidal anti-inflammatory drugs is more effective at reducing inflammation than either agent used alone. Creatine and nifedipine, when used together, may improve the function of the heart, although research in this area is early. In theory, creatine may alter the activities of insulin and should be used carefully by those who take prescription drugs to control blood sugar levels.
Interactions With Herbs And Dietary Supplements
Creatine may increase the risk of adverse effects, including stroke, when used with caffeine and ephedra. In addition, caffeine may reduce the beneficial effects of creatine during intense intermittent exercise. Creatine may reduce the effectiveness of vitamins A, D, E and K. In theory, creatine could alter the activities of insulin and should be used carefully by those who take herbs or supplements that affect blood sugar levels, such as bitter melon (Momordica charantia). It is possible that creatine may increase the cholesterol-lowering effects of herbs and supplements that lower cholesterol levels, such as red yeast (Monascus purpureus).
Dosing
The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care provider before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.
Typically, creatine is dosed four times daily for supplementation and twice daily for maintenance. Sixty-four ounces of water should be consumed daily to avoid dehydration. There are no standard doses of creatine, and many different doses are used traditionally.
Adults (Aged 18 Or Older)
Powder, oral: For enhanced athletic performance, a dose of 20 grams daily for four to seven days has been used. Maintenance doses range between two and five grams daily or 0.3 milligrams per kilogram of body weight daily. A dose of 1.5 grams daily has been used for hyperornithinemia. For neuromuscular diseases, including muscular dystrophy, a dose of 10 grams daily has been suggested, although lower doses (five grams) and higher doses (20 grams) have also been used. For GAMT deficiency, a dose of 400 to 670 milligrams per kilogram of body weight daily has been used. For treating high cholesterol levels, various dosing regimens have been used. Examples include 20 grams daily for five days, followed by 10 grams daily; 25 grams initially for seven days, followed by five grams; or 15.75 grams daily for five days, then 5.25 grams daily. In the treatment of McArdle's disease, a dose of 150 milligrams per kilogram of body weight has been used daily for five days, followed by 60 milligrams per kilogram daily for five weeks.
Intravenous/intramuscular: Numerous dosing regimens have been used in studies in humans. Intravenous dosing should be conducted only under medical supervision.
Children (Younger Than 18)
A dose of five grams daily has been used in children with muscular dystrophy, and various doses have been used in children with GAMT deficiency, including two grams per kilogram of body weight, four to eight grams daily in an infant and 400 to 670 milligrams per kilogram of body weight. Dosing in children should be done under medical supervision because of potential adverse effects.
Summary
Creatine has been suggested as a treatment for many conditions. There is some research supporting the use of creatine for enhanced muscle mass, for chronic heart failure, for certain neuromuscular diseases and for hyperornithinemia. It is not clear what doses may safe and effective. There is not enough scientific evidence to support the use of creatine for any other medical condition. Creatine may increase the risk of dehydration, electrolyte imbalances and kidney disease. It should be avoided in pregnant or breast-feeding women and used very carefully in children. Consult your health care provider immediately if you have any side effects.
The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.
Resources
Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research
Selected Scientific Studies: Creatine
Natural Standard reviewed more than 250 articles to prepare the professional monograph from which this version was created.
Some of the more recent English-language studies are listed below:
Bemben MG, Bemben DA, Loftiss DD, et al. Creatine supplementation during resistance training in college football athletes. Med Sci Sports Exerc 2001;33(10):1667-1673.
Ferraro S, Codella C, Palumbo F, et al. Hemodynamic effects of creatine phosphate in patients with congestive heart failure: a double-blind comparison trial versus placebo. Clin Cardiol 1996;19(9):699-703.
Gordon A, Hultman E, Kaijser L, et al. Creatine supplementation in chronic heart failure increases skeletal muscle creatine phosphate and muscle performance. Cardiovasc Res 1995;30(3):413-418.
Izquierdo M, Ibanez J, Gonzalez-Badillo JJ, et al. Effects of creatine supplementation on muscle power, endurance, and sprint performance. Med Sci Sports Exerc 2002;34(2):332-343.
Jacobs PL, Mahoney ET, Cohn KA, et al. Oral creatine supplementation enhances upper extremity work capacity in persons with cervical-level spinal cord injury. Arch Phys Med Rehabil 2002;83(1):19-23.
Jowko E, Ostaszewski P, Jank M, et al. Creatine and beta-hydroxy-beta-methylbutyrate (HMB) additively increase lean body mass and muscle strength during a weight-training program. Nutrition 2001;17(7-8):558-566.
Klopstock T, Querner V, Schmidt F, et al. A placebo-controlled crossover trial of creatine in mitochondrial diseases. Neurology 2000;55(11):1748-1751.
Leenders NM, Lamb DR, Nelson TE. Creatine supplementation and swimming performance. Int J Sport Nutr 1999;9(3):251-262.
McNaughton LR, Dalton B, Tarr J. The effects of creatine supplementation on high-intensity exercise performance in elite performers. Eur J Appl Physiol Occup Physiol 1998;78(3):236-240.
Mujika I, Padilla S, Ibanez J, et al. Creatine supplementation and sprint performance in soccer players. Med Sci Sports Exerc 2000;32(2):518-525.
Vorgerd M, Zange J, Kley R, et al. Effect of high-dose creatine therapy on symptoms of exercise intolerance in McArdle disease: double-blind, placebo-controlled crossover study. Arch Neurol 2002;59(1):97-101.
