Creatine supplement side effects, safety, risks, benefit for bodybuilding and muscle growth, does it help athletes in different sports? Are there toxic effects if used daily for prolonged periods? What is the right dosage for long term use? Honest information by Dr. Ray Sahelian, M.D, bestselling author of Creatine: Nature's Muscle Builder. Review of usage by teenagers, vegetarians, vegans, and those with kidney disease
April 3 2014

If you are planning to take a creatine monohydrate supplement for prolonged periods to increase muscle mass and strength, consult your physician if you have medical problems or if you are taking medications, and please read this article.
   A cautious approach would be to limit intake to 3 to 5 grams almost every day for two weeks followed by 3 grams two to four times a week. It would be wise to take a few days off each month. It would also be safer to take two full weeks off every 3 to 4 months. Of course these guidelines will vary between individuals. The amount and frequency of use depends on how much muscle gain a person wants to maintain. Athletes and large individuals would require higher amounts, while non-athletes and smaller individuals would require less.
There are a number of other factors that influence the amount of creatine intake including diet, sex, age, concurrent use of other supplement or medicines, medical condition, genetics, etc.
   After the creatine supplement is completely stopped, there is often a gradual decrease in muscle mass over time (days and weeks) probably to the level that it was before use. The rate of this decrease varies among individuals and also depends on dietary intake of creatine, protein and workout regimen. Taking this dietary supplement again generally restores muscle mass rather quickly.

What is it? Where is it found?
Creatine is not an herb, mineral, vitamin, hormone, or steroid. It is a natural nutrient found in our bodies and the bodies of most animals. Approximately 95% of the body's supply is found in the skeletal muscles. The remaining 5% is scattered throughout the rest of the body, with the highest concentrations in the heart, brain and testes.
    The human body gets most of the creatine it needs from food or dietary supplements. This nutrient is easily absorbed from the intestinal tract into the bloodstream. When dietary consumption is inadequate to meet the body's needs, a limited supply can be synthesized from the amino acids arginine, glycine and methionine. This production occurs in the liver, pancreas and kidneys.

Buy Creatine Powder and Capsules, available for sale
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Creatine Powder in a bottle and 700 mg per capsule. Creatine is a natural substance found in most protein foods, however the supplement that is produced and placed in powder or capsule form is made synthetically in a laboratory.

Suggested use: Take about 3 grams (about a flat teaspoon) daily for one month with a break of 2 days a week. Best time to take this supplement is before, during, or after a workout, although it will work even if taken at other times of the day.


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Email from a reader:
Thank you so much for your information that you provide. I feel certain that I speak for all of us when I say that we don't really want to get our information from some weight-lifting magazine article writer of possibly dubious background. If you were not here, we would have little choice.

Who can benefit
Thus far it appears that the greatest benefits occur in those who wish to put on muscle mass and increase strength.
   Athletes in bodybuilding, powerlifting, martial arts, and track and field events such as shot put may benefit due to greater strength. Wrestlers and football players could also benefit, and perhaps baseball players with a more powerful swing or pitch. Body builders and anyone who wishes to have more muscle build will find it extremely helpful. Creatine supplement may even be helpful for soccer players or sprinters.
Low doses may be useful in combating exercise induced fatigue. It is a legal substance for use in the Olympics or in professional competitions.
   It is still unclear whether athletes involved in endurance activities such as marathon running or long-distance bicycling will benefit. There have been anecdotal reports that people in these sports may benefit, although most studies show that it either does not help or may actually hurt. The difficulty in these situations appears to center on the increased muscle mass which creatine provides. While that's great if you're a bodybuilder or wrestler, it can be a detriment if you have to carry all that weight around during a marathon or triathlon. It becomes a tradeoff between the increased strength you get and the increased muscle mass. Further research will provide us with more definitive answers as to what role supplementation plays in endurance-type sports.

If muscle mass is slowly decreased after the use of creatine if weight training is continued, then what is the point of taking it if you are back where you started?
   This muscle builder can be used at the start of an exercise program to motivate working out and overcoming the initial inertia that so often accompanies those who are just starting an exercise program. The motivation is due to the gains in muscle mass that come much quicker while on creatine. Many people don't stop using it completely but take 3 grams two to three times a week which seems to be enough to maintain the gain in muscle mass.

Vegetarians
A study published in the British Journal of Nutrition showed that cognitive functioning in vegetarians was improved with creatine supplementation. The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores. Br J Nutr. 2010.

Eur J Nutr. December 2013. Short-term creatine supplementation does not reduce increased homocysteine concentration induced by acute exercise in humans.

Soccer
Twenty young male soccer players participated in the study and were matched and allocated to 2 randomly assigned trials: ingesting creatine-monohydrate supplement (3 x 10-g doses) or placebo for 7 days. The main finding of the present study indicates that supplementation with creatine in young soccer players improved soccer-specific skill performance compared with ingestion of placebo. Ostojic SM. Sports Medicine Institute, Yugoslavia. Int J Sport Nutr Exerc Metab. 2004.

Tennis game
Compared with placebo supplementation, neither six days nor five weeks of creatine supplementation had any significant effect on serving velocity, forehand velocity, or backhand velocity, a research team reports in the June, 2006 issue of the British Journal of Sports Medicine. Taking it also had no significant effect on repetitive sprint power or upper or lower extremity strength.
   In my opinion, it is not likely to be of significant help in sports that are based mostly on fine motor skills.

Additional benefits

Amyotrophic lateral sclerosis
A placebo-controlled trial did not find evidence of a beneficial effect of creatine monohydrate on survival or disease progression in patients with ALS.

Brain function, cognitive skills
Supplements may boost cognitive function in vegetarians. This nutrient may be helpful for memory enhancement in older individuals, but not in those who are young.

Cancer
Creatine is normally found in our bodies and some of the foods we eat, especially meats and fish. We ingest about a gram a day through food and another gram is made by the body. It is possible that high doses over prolonged periods could create toxins (creatine converts into creatinine) and cause harm to the body, and hence the smallest amount should be used to provide the necessary muscle gains. I am not aware of any studies that have shown supplementation causing cancer in humans or animals.

Depression and use with antidepressants
Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that includes fluoxetine (Prozac), paroxetine (Paxil) and sertraline (Zoloft) and escitalopram (Lexapro).

Antidepressants targeting monoaminergic neurotransmitter systems, despite their immediate effects at the synaptic level, usually require several weeks of administration to achieve clinical efficacy. Fifty-two women with major depressive disorder were enrolled in an 8-week double-blind placebo-controlled clinical trial and randomly assigned to receive escitalopram (Lexapro) in addition to either creatine (5 g/day) or placebo. Patients receiving creatine augmentation showed significantly greater improvements. Creatine augmentation of SSRI treatment may be a promising therapeutic approach that exhibits more rapid and efficacious responses in women with major depressive disorder. A Randomized, Double-Blind Placebo-Controlled Trial of Oral Creatine Monohydrate Augmentation for Enhanced Response to a Selective Serotonin Reuptake Inhibitor in Women With Major Depressive Disorder; American Journal of Psychiatry (Aug 2012).

Diabetes
Diabetics have a tendency to eventually have kidney damage if their blood sugar is not well controlled. Creatine should not influence blood sugar to any significant extent, but since very high doses may harm the kidneys over the long run, someone who is diabetic should not take more than 1 gram a day. Creatinine blood levels should be monitored every few months.

Duchenne muscular dystrophy
Creatine supplement may be helpful in certain muscular dystrophies (facioscapulohumeral dystrophy, Becker dystrophy, Duchenne dystrophy, sarcoglycan-deficient limb girdle muscular dystrophy). It has not found to be helpful in those with Myotonic Dystrophy Type 1.

Creatine monohydrate enhances strength and body composition in Duchenne muscular dystrophy.
Thirty boys with Duchenne muscular dystrophy (50% were taking corticosteroids) completed a double-blind, randomized, cross-over trial with 4 months of creatine (about 0.10 g/kg/day), 6-week wash-out, and 4 months of placebo. Four months of supplementation led to increases in handgrip strength in the dominant hand and a reduction in a marker of bone breakdown and was well tolerated. Neurology. 2004.

Fatigue
Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain. Nutrition. June 2010. Dosage used was 0.03 grams per kilo of body weight for a period of six weeks.

Heart tissue
I still don't have a good understanding, myself, on how creatine influences heart muscle. I would like to see studies evaluating cardiac size and function after supplementation.

Lung disease, COPD
Creatine supplementation during pulmonary rehabilitation in chronic obstructive pulmonary disease.
Skeletal muscle wasting and dysfunction are strong independent predictors of mortality in patients with chronic obstructive pulmonary disease (COPD). Thirty eight patients with COPD were randomised to receive placebo or creatine monohydrate 5.7 g supplements in a double blind trial. Supplementation led to increases in fat-free mass, peripheral muscle strength and endurance, health status, but not exercise capacity. Thorax. 2005.

Muscle recovery after heavy exercise
Taking creatine supplements before and after a tough workout improves muscle recovery. Journal of the International Society of Sports Nutrition, online June 2, 2009.

Parkinson's disease
The National Institute of Neurological Disorders and Stroke, one of the U.S. National Institutes of Health, has launched a trial as the first in a series of government-sponsored studies of new Parkinson's treatments. The NINDS has recruited 1,720 people with early-stage Parkinson's disease across the United States and Canada. Patients and doctors alike will not know whether they are getting creatine monohydrate or a placebo. The study is due to last three to five years. Creatine monohydrate may affect the mitochondria -- structures that produce energy inside cells. Palo Alto, California-based Avicena Group, Inc. provided the purified creatine monohydrate for the trial. The company has also been testing creatine monohydrate against the nerve disorders Huntington's disease and amyotrophic lateral sclerosis, also known as ALS.

Long-term creatine supplementation is safe in aged patients with Parkinson disease.
Nutr Res. 2008.
Sixty patients with Parkinson disease received either oral creatine or placebo with a dose of 4 g/d for a period of 2 years. Although serum creatinine levels increased, all other markers of tubular or glomerular renal function, especially cystatin C, remained normal, indicating unaltered kidney function.

Form and timing, how to ingest it
As to the timing of intake -- whether before a workout, or after a workout -- I have not seen specific studies evaluating the best time to take. Creatine can be taken with practically any fluid, and my preference is fruit or vegetable juices since they contain many vitamins and phytonutrients. One can add protein powder, and other health / vitamin / green powders. When taken with a small amount of food, nausea is less likely to occur than what sometimes happens when taken on an empty stomach. Drinking additional water may be helpful. It has been reported that simultaneous ingestion with caffeine slightly reduces its effectiveness.
   Creatine will increase the size of muscles even without working out, but the gains are minimal compared to doing so with a workout. Muscle size will likely decrease a few days or weeks after stopping its use, particularly if one stops working out. The use of creatine supplements will increase body weight, in part due to water retention. It's possible that taking alpha lipoic acid along with it improves the transport it into muscle tissue.

I have recently seen ads for creatine alpha keto glutarate, Ethyl Ester HCl and Tricreatine Malate. What is the advantage of taking Creatine Alpha Keto Glutarate, Ethyl Ester HCl and Tricreatine Malate?
    Hardly any human research and comparisons have been done with these forms. Therefore, for the time being, I prefer to stay with monohydrate form since it works very well.

Creatine serum is not as effective as powder for improving cycle sprint performance in competitive male team-sport athletes.
This study examined the effects of supplementation with either creatine monohydrate powder in solution or a widely available creatine serum on performance in a repeated maximal sprint cycling test. Subjects' total work and peak power in the cycle sprint improved significantly after loading with monohydrate powder, but there was little change after loading with serum. J Strength Cond Res. 2004.

Sexual health
I am frequently asked if this natural muscle builder enhances or decreases sex drive. I do not believe it has much of an influence either way. I don't think it causes sexual dysfunction. It doesn't seem to have a direct effect on libido, although feeling good about one's toned body could influence self-image and how others react to us and make us feel more attractive and sexual. The influence on sperm count or motility, if any, is not known at this time. There are no reports to date that it influences the size of genital organs.

Vegans and those who don't consume much meat or fish
Vegetarians, particularly those who are on a strict lacto-ovo-vegetarian (LOV) diet do not ingest much creatine since this nutrient is mostly found in meats, fish, and chicken. In a study published in the Journal of Sports Nutrition and Exercise Metabolism, thirty-two healthy men, who regularly consumed an omnivorous diet, were split into two groups. One group consumed a LOV diet while the other group had an omnivorous diet (they ate everything). The study lasted 26 days. In addition to their diet, on day 22 of the study, subjects were assigned in a double-blind manner to receive either creatine monohydrate 0.3 g per kilogram of body weight per day or an equivalent dose of placebo for 5 days. Consuming a LOV diet for 21 days decreased muscle creatine concentration in individuals who normally consume meat and fish. However, the creatine content of muscle in the LOV group returned back to normal after a period of only 5 days.
   At 5 g a day for six weeks, it has been shown to improve brain performance (memory and intelligence) in adults who are vegetarian.

Teenagers, adolescents, children
At this point I do not recommend anyone younger than 18 to use creatine except under medical supervision. If your personal physician and parents approve your use, it should only be taken for a brief period of time, such us a couple of months for a particular sports season, and then you should be off it the rest of the year. Daily dosage is best kept to 3 gm or less, with two days off per week.
   I am uncomfortable with teenagers using it without supervision since they often do not know their limits. Since creatine is readily available over the counter, it is unlikely that we can prevent teenagers from using it. Therefore, a "Just Say No" policy won't work. What we can do, though, is have a balanced viewpoint and encourage communication between teenagers, parents, coaches, and a physician. I am definitely against teenagers using hormones.

Creatine side effects, safety, risks and cautions - are there any dangers? Is it safe?
Nausea, stomach upset, dizziness or weakness, loose stools, diarrhea, and weight gain are the most common creatine side effects, and generally occur with dosages greater than 5 grams a day. Another side effect sometimes reported is muscle cramping. Strains and sprains can occur (perhaps even muscle tears?) when individuals enthusiastically and rapidly increase their workout regimen before their tendons and ligaments have adapted to the increase in muscle size and power. 
   Long-term side effects of daily ingestion, especially in high dosages, are currently not known. There is a possibility that excess intake can put stress on the kidneys and liver. Creatine converts into creatinine which, in high dosages, could act as a toxin. Whether there is a potential for increasing the risk of cancer with regular high dose use is currently not known. I discourage the regular, high dose use unless frequent breaks are taken. Individuals with kidney disease should not use this natural product.
   One study shows long term creatine use for 21 months did not influence blood studies
(metabolic markers, muscle and liver enzymes, electrolytes, lipid profiles, hematological markers, and lymphocytes). Kreider RB, et al. Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Mol Cell Biochem. 2003.
   I have also come across a few anecdotes about high dose creatine causing adverse reaction such as anxiety, irritability or depression. Time will tell whether it is responsible for these cognitive changes.
  
Short term supplementation does not seem to affect blood pressure, heart rate, or kidney function. A small to modest amount of alcohol intake should not interfere with low dose use. I don't advise taking it while pregnant. There are no credible reports of hair loss as a creatine side effect.

I have a friend who's husband was using 3-5 mg of creatine three times a week and no other supplements of any sort were being taken. Within 2 weeks of taking it he became extremely edgy and his temper wouldn't just come out of no where but it would also become unmanageable. They both consulted different internet groups and finally decided that he should discontinue use. It has been 4 months now and he has had no problems with his temperament or edginess.

I read an article online that said, "Taking creatine can result in kidney damage, result in significant dehydration and has been purported to worsen asthma." What is your opinion on this?
   In very high doses used daily without taking any breaks it is possible that it could harm kidneys or cause other conditions we don't know of yet. But, in my opinion, taking 3 grams a day with a day or two off a week should not cause any harm.

Depression and low mood, testimonials
I just started taking creatine and was on the loading dose for the first couple of days and got extremely depressed. I stopped taking it and I am feeling fine. I took it again just to see if I could recreate the experience as I felt physically strong and yes I got depressed.

I had been taking 5 g each day for about 5 weeks. It provided just the boost I needed for my workouts but unfortunately, now I realize that it also made me depressed. I have a history of depression and have been in therapy for a few years now. I began to notice a change in my mood about 2 weeks after starting it. I felt tired, cranky and a definite lack of enthusiasm for things I normally enjoyed. I quit taking it one week ago and am feeling like my old self again.

I don't see anything on your site about it increasing the chance of kidney stones. I took 3-5 grams each day 2 years ago and developed a stone on my left side after a few months. I stopped the creatine and also doubled my daily water intake. Now 2 years later I tried it again and on my 2nd 1-month cycle I got another stone, this time on my right side. Have you seen any connection between creatine and kidney stones?
   This is the first report we have had regarding this possible adverse reaction.

You are the only one that recommends only 3 g and taking a week off every month. Although there is no conclusive proof that too much creatine may cause things like depression and anxiety attacks I can speak from personal experience that it caused me to experience both of those things. Two years ago I started taking 6 to 8g of creatine a day after the loading phase and other than occasional diarrhea I did not experience any problems. I did however gain size, some weight and the intensity of my workouts increased which is why I started taking it in the first place. Then about a year ago I  had rotator cuff surgery and could not work out for 6 months. When I started back lifting I also started to taking creatine again at the same dosages but began to experience anxiety attacks, the attacks continued until recently when quite by accident I found that within 2 hours after I took 6 grams creatine I began to get depressed and anxious but on the days that I forgot to take it I was fine. I have since cut back my creatine intake to 3-4g every other day as your site suggests and I am no longer experiencing anxiety attacks. I thank God I found your site as I really thought I was going crazy.

Irritability and anger
I am an 18 year old creatine user for about 3 years. My parents and I have both noticed increased anger and irritability from the continued use. However, after short recesses in-between uses, the side-effects wear off.

Is there harm kidney function or danger to the renal system? Effect on creatinine levels
Thus far it appears that low dosages, such as 1 to 3 grams every other day, appear to not cause any harm to kidneys. We get questions from parents concerned about the use of creatine monohydrate by their teenage sons and daughters. Its influence on kidney health is not clear, but to be on the safe side it is important not to take this supplement every day but rather 3 or 4 days a week with a full week off each month. If teenagers were to use creatine monohydrate supplement for weight lifting, the dosage should be limited to 3 grams a day with 2 days off each week and a full week off each month, and a full month off every 3 months. Your son's doctor should approve of this treatment. We have not had any reports of kidney harm when limited to these dosages and when breaks are taken as we advise. However there have been reports in the medical literature of individuals having causing harm to the kidneys when using high dosages of creatine along with many other supplements.

Acute renal failure in a young weight lifter taking multiple food supplements, including creatine monohydrate.
J Ren Nutr. 2006.
We report a case of a healthy 24-year-old man who presented with acute renal failure and proteinuria while taking creatine monohydrate and multiple other supplements for bodybuilding purposes. A renal biopsy showed acute interstitial nephritis. The patient recovered completely after he stopped taking the supplements.

Effect of oral creatine supplementation on urinary methylamine, formaldehyde, and formate.
Med Sci Sports Exerc. 2005.
Twenty young healthy men ingested 21 g of creatine monohydrate daily for 14 consecutive days. Supplementation increased plasma creatine content 7fold and urine output 141 fold with no effect on creatinine levels. Twenty-four-hour urine excretion of methylamine and formaldehyde increased, with no increase in urinary albumin output.

Few adverse effects of long-term creatine monohydrate supplementation in a placebo-controlled trial.
Int J Sports Med. 2005.

We performed a double-blind, placebo-controlled trial of creatine monohydrate in patients with the neurodegenerative disease amyotrophic lateral sclerosis. 175 subjects were randomly assigned to receive 10 g daily or placebo. No significant adverse effects occurred. After two months of treatment, edematous limbs were seen more often in subjects using creatine monhydrate, probably due to water retention. Severe diarrhea and severe nausea caused 3 subjects in to stop intake, after which these adverse effects subsided. Long-term supplementation did not lead to an increase of plasma urea levels or to a higher prevalence of micro-albuminuria.

How does it work in the body?
Creatine is an essential player in the primary energy source used for muscle contraction. It exists in two different forms within the muscle fiber: as free (chemically-unbound) and as creatine phosphate. This later form makes up two-thirds of the total supply. When your muscles contract, the initial fuel for this movement is a compound called ATP. ATP provides its energy by releasing one of its phosphate molecules. It then becomes a different compound called ADP. Unfortunately, there is only enough ATP to provide energy for about 10 seconds, so for muscle contraction to continue, more ATP must be produced. Creatine phosphate comes to the rescue by giving up its phosphate molecule to ADP, recreating ATP which can then be burned again as fuel for more muscle contraction.
   Your ability to regenerate ATP depends on your supply of creatine. The more there is the more ATP is remade, and more ability to train your muscles to their maximum potential. This greater ATP synthesis also keeps your body from relying on another energy system called glycolysis, which has lactic acid as a byproduct. This lactic acid creates the burning sensation you feel during intense exercise. If the amount of acid becomes too great, muscle movement stops. But if you keep on using ATP because of all the creatine you have, you can minimize the amount of lactic acid produced and actually exercise longer and harder. This helps you gain strength, power and muscle size; and you won't get fatigued as easily.
   Creatine has also been shown to enhance your body's ability to make proteins, especially the proteins within the muscle fibers. Two of these proteins, actin and myosin, are essential to all muscle contraction. So when you build up your supply of these contractile proteins, you actually increase your muscle's ability to perform physical work. And the more work you do (whether it's lifting weights or running 100-meter dashes), the stronger you become over time. It can also absorb intracellular water, thus resulting in a higher muscle volume. This could lead to the "pumped up" feeling and look. An additional way creatine increases muscle size is thought to be its fluid retention abilities within muscle tissue.

Safety of long term ingestion
To investigate long-term effects of supplementation, 18 professional basketball players of the Spanish Basketball League participated in a longitudinal study. The subjects ingested 5 g creatine monohydrate daily during three competition seasons. Blood studies over a 3 year period did not indicate any major abnormalities. Risk assessment of the potential side effects of long-term creatine supplementation in team sport athletes. Eur J Nutr. 2004.
   Dr. Sahelian says: Daily supplementation with 5 grams for 8 months of the year appears to be safe. Still, I would prefer taking an additional one week off each month just to be extra safe.
We have had reports of elevated creatinine levels and liver enzymes with heavy users, however since these were not controlled studies, we still are not sure.

Combination with glutamine and BCAA supplements
Creatine supplements may be taken the same day as glutamine supplements and BCAA supplement as long as the dosages are reasonable. BCAA include valine, leucine, and isoleucine amino acids.

Combination with prescription medications
Creatine has not been tested in combination with other medicines to find out if it alters their metabolism, but I don’t have any reasons to suspect that it would do so in any major way.

Emails
Is taking creatine monohydrate the best way to gain weight and muscle if you a are a tall thin person?
   Protein supplements, deep sleep, perhaps glutamine, and lots of time in the gym are helpful.

I was wondering if you have ever heard of creatine supplement use causing a higher than normal CPK level; for instance 1900? I used the product Cell Tech which has 10g per serving, but was off it for 7 weeks before having a CK test.
   CPK stands for creatine phosphokinase. There are several types of CPK. CPK--BB (CPK1) is found primarily in brain tissue, CPK--MB (CPK2) is found primarily in heart muscle, and CPK--MM (CPK3) is found primarily in skeletal muscle. It would be helpful to know which type your doctor can find. I don't think it's farfetched that creatine ingestion has a role in influencing CPK--MM, but I have not come across this finding yet until the issue is clarified.

I bought your book "CREATINE: Nature's Muscle Builder" years ago; second only to the BIBLE, this book helped me a great deal in achieving the results I saught. My question is regarding the shelf life of the following supplements: EAS Myoplex Delux protien, Betagen their creatine & HMB, Next Nutrition's whey protien & Sport Pharma's Vanadyl and Thermadrene. I purchased these products & have a large quantity of them in my pantry (climate controlled in the house). They are 4-5 years old. Would you be afraid to consume them at this point in time? They still look & smell fine. In college I worked in a pharmacy & was told that after a drugs "expiration date" they didn't become poison, but over time their potency would decline.
   It is difficult to estimate expiration dates on supplements, but many of them can decompose and either not be as effective or potentially decompose into undesirable substances. Health is more important than money. It would be preferable to take fewer supplements but of higher quality and freshness.

My athletic 18-yr old son plays varsity sports in high school: soccer, basketball, and lacrosse. He works out and lifts weights daily. He also ingests about 4g of creatine daily (Phosphagen). He does not take steroids or any other protein supplement. We have noticed that he has become extremely short-tempered, argumentative, and stressed out about the most trivial things. Because this behavior is also typical teenage behavior, it was difficult to make a connection between the creatine and the hot-headed-behavior until we talked with other parents who had experienced the same symptoms in their teenage sons who were also taking creatine. With a great deal of resistance, we are making our son stop taking it, and we hope to see his less-difficult personality re-emerge--our friends indicated that it took about a month for them to see a change in behavior after their sons stopped.
   Although creatine may be the culprit, we should keep in mind that many people who take it are also taking other supplements, such as hormones or stimulants, that may cause irritability.

I have been using creatine off and on for 3 years and have noticed the following scenarios to be predictable. During the loading dose week there is no doubt that I experienced a significant increase in muscle mass. I will attempt and lift heavier weights in squat, bench, and deadlift. And invariably, I wind up with an injury, (ie. low back or groin tear) that requires a several week set back. I will attempt longer and more challenging road bike rides in the mountains than I would usually tackle...and I will cramp during the last quarter of a 70 mile ride.

Research studies
Creatine monohydrate supplementation on body weight and percent body fat.
J Strength Cond Res. 2003.
Seventeen active young males participated in a study to examine the effects of creatine monohydrate supplementation on total body weight (TBW), percent body fat, body water content, and caloric intake. Supplementation was given for 4 weeks (30 g a day for the initial 2 weeks and 15 g a day for the final 2 weeks). Significant increases before and after the study were found in TBW and body water content for the creatine group. No significant changes were found in percent body fat or daily caloric intake. Weight gain in lieu of creatine supplementation may in part be due to water retention.