Creatine: benefits, side effects and the right dose — what the science actually says

In short

• Creatine is one of the most researched and most effective supplements for muscle growth and building strength.

• The recommended dose is 3–5 g per day, including rest days.

• A loading phase isn't mandatory, but it speeds up the filling of the muscles' creatine stores.

• The most common side effects are 1–2 kg of water binding into the muscles and, at high doses, possible mild stomach discomfort.

• Studies do not support claims that creatine causes kidney damage, dehydration, or cramps in healthy people. The cognitive benefits are real, but often overstated.

• Creatine obviously doesn't replace a proper training program: it's an add-on on top of good training, not a shortcut around it.

This article walks through what creatine does in the body, who should use it, what the proven benefits are, which of the claimed side effects hold up and which don't, how much creatine to take, and what kind of creatine to buy.

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What is creatine and how does it work?

Creatine is a natural compound that the body produces itself from amino acids, roughly one gram per day, mainly in the liver and kidneys. On top of that, an omnivore's diet provides about 1–2 g per day, in practice from meat and fish.

Creatine's main job is to help produce energy in short, high-intensity efforts, such as heavy gym sets or short power efforts like sprints. When the muscles' creatine stores are full, you can often do one or two more reps at the same weight at the gym. In a single workout the difference is small, but over months and years it can show up as a greater training load, better strength development, and more muscle growth.

The mechanism, physiologically: In the muscles, creatine is stored mainly as phosphocreatine. When a muscle does work, it uses ATP, the body's most important energy molecule. Phosphocreatine donates its phosphate group to ADP, and ATP is reformed almost immediately. This so-called "fast" energy system is responsible in particular for the first roughly 10 seconds of high-intensity work — that is, exactly the length of time a heavy gym set usually lasts.

What are the benefits of using creatine?

Creatine is one of the few supplements whose effectiveness and safety have been convincingly demonstrated in hundreds of studies. Relative to its effect, it's also cheap. Not all of the claimed benefits are backed by equally strong evidence, however. Some effects have been demonstrated convincingly, while others still rest on fairly limited research.

Benefit	Strength of the evidence	In practice:
Strength and power output	Strong, hundreds of studies	A few percent more strength and slightly better staying power in sets, i.e. more reps
Muscle growth	Strong	Over the long term, more muscle growth through an increased training load
High-intensity performance (e.g. sprints, power)	Strong	Better power and recovery between sets
Cognition and the brain	Weak–moderate	Benefits show up mainly in stressed states (sleep deprivation, ageing, illness). At a typical 3–5 g dose, the effect in a healthy adult is probably small.
Bone	Weak	In human studies the effect has been nonexistent.
Inflammation and oxidative stress	Weak–moderate	Possibly slightly favourable, not a reason to start using it

How creatine works: strength, power and muscle growth

The evidence is clearly strongest for developing strength, power output and muscle mass. In meta-analyses the effect sizes typically fall between 0.3 and 0.6 (Branch 2003, Forbes et al. 2021), meaning the effect is clear but moderate. In practice, creatine often makes one or two more reps at the same weight possible, or a slightly larger training load. Over months, this small edge accumulates into a measurable difference in strength and muscle mass.

Where creatine may also help: the brain and cognition

Creatine's benefits for the brain are considerably more uncertain than its benefits for performance and muscle growth. Although the topic is talked about a lot, the research evidence in healthy adults is still fairly weak.

The brain's creatine content doesn't respond to supplementation as strongly as the muscles' does. In vegetarians, muscle creatine stores are on average lower than in omnivores, but no corresponding difference has been observed in brain creatine content. According to a review by Roschel et al. (2021), creatine supplementation raised brain creatine content by about 5–10%, whereas in muscle the increase is typically 20–40%. A meaningful effect on the brain may require considerably larger doses than usual.

So far, cognitive benefits have mainly been seen in situations where the brain is under greater strain than usual, such as sleep deprivation, oxygen shortage, in older adults, or in connection with certain illnesses. In a healthy, well-rested adult, the usual 3–5 grams per day probably won't meaningfully improve memory, concentration, or other cognitive performance.

What are the side effects of creatine?

Creatine's side effects are considerably milder than is often claimed. Creatine monohydrate has an exceptionally good safety profile for a supplement, and it has been studied in hundreds of trials, some of which have followed use for as long as five years. In healthy people, no serious adverse effects have been observed. Even though there are studies showing creatine to be safe in long-term use, everyone should still monitor how their own body reacts on a case-by-case basis.

The most common effects of creatine are a 1–2 kg increase in weight (water accumulating in the muscles, not fat) and possible mild stomach discomfort. Claims of kidney damage, liver damage, dehydration, or increased cramping, on the other hand, are not supported by the research evidence in healthy people.

Claim	What the research says
Creatine damages the kidneys	No research evidence in healthy people. An elevated creatinine reading in a blood test is a breakdown product of creatine, not a sign of kidney damage.
Creatine strains the liver	No research evidence in healthy people.
Creatine causes dehydration	No research evidence. Creatine increases the body's total fluid volume and may even improve thermoregulation.
Creatine causes cramps and strains	No research evidence. Some studies even point to a lower injury risk.
Creatine raises body weight	Yes. Weight usually rises by 1–2 kg as water binds into the muscles, not because of fat gain.
Creatine causes stomach discomfort	Partly. The most common possible side effect, which can usually be avoided by adjusting the dose or how it's taken.
Creatine causes hair loss	The evidence is very weak. The claim rests on one old study that has never been replicated.
Creatine disrupts sleep	No research evidence.
Creatine causes bloating	No research evidence.
Creatine causes acne	No research evidence.

Weight gain

When the muscles' creatine stores fill up, water also binds into the muscle cells. In loading-phase studies, weight rises typically by 1–2 kg, and the body's total water content increases by about 1.3–2.3 litres.

This isn't fat, nor swelling in the wrong places. In practice, moderate weight gain is a sign that creatine is working for you. If you're dieting and tracking your weight, a slow rise over 2–4 weeks can mask actual fat loss. In this situation a loading phase is actually justified: your weight rises all at once over a few days, after which you can continue tracking from a new baseline.

If tracking weight is on your mind anyway, it's also worth reading how how much protein per day to eat during weight loss.

Stomach discomfort

Stomach discomfort is a side effect that affects some people, though it's not very common. Typical symptoms in that case are bloating, loose stools and burping. They almost always relate to too large a single dose, or to the creatine powder not having dissolved properly. Most often the problem clears up without having to stop using creatine. Try these approaches in this order:

• Stop the loading phase and switch to the maintenance dose (3–5 g/day).

• Take creatine with a meal.

• Dissolve the powder thoroughly in a larger volume of liquid or a warm drink.

• Split the daily dose into two parts (e.g. 2 × 2.5 g).

Kidneys and liver

Can creatine damage the kidneys or liver? In healthy people, the research evidence doesn't support this claim.

The confusion comes from the fact that creatinine is a breakdown product of creatine, and it's used as a screening test for kidney function. When you use creatine (3–5 g per day), the creatinine value in a blood test can rise. That doesn't mean kidney function has declined, though — simply that the body is breaking down more creatine.

If you have blood tests while using creatine, tell your doctor about it before your kidney values are interpreted. An abnormal result shouldn't be brushed aside, but it needs to be assessed in the right context.

Studies have not repeatedly found that creatine damages the kidneys or liver of healthy people. If you have a diagnosed kidney or liver condition, however, talk with your doctor before starting to use creatine.

Hair loss

The claim that creatine causes hair loss rests on one 2009 study in which DHT levels rose in rugby players using creatine. The study didn't actually measure hair loss, the result has never been replicated, and based on current evidence creatine has not been shown to cause hair loss.

Using creatine: how much creatine should you take?

The basic dose is 3–5 g of creatine monohydrate per day, every day, including rest days. With this, the stores fill up in about 3–4 weeks. Creatine is usually taken once a day with water.

The dose can also be scaled to body weight. Based on studies, an effective dose is about 0.04 g per kilogram of body weight per day, but for most adults 3–5 g of creatine monohydrate per day is the best recommendation.

Body weight	Recommended daily dose
50–70 kg	3 g
70–90 kg	3–5 g
Over 90 kg	5 g

A daily dose below 3 g may end up ineffective. In studies, 1–2 g per day has not improved performance, muscle mass, or functional capacity, so for most people a safe recommendation is at least 3 g per day.

Should you load creatine?

Usually no. In a loading phase you take 20–25 g of creatine per day for 5–7 days, after which you switch to a 3–5 g maintenance dose. Loading fills the creatine stores in about a week, whereas without loading it takes about 3–4 weeks. The end result is the same, though.

Loading is mainly useful when you want the effect available quickly, or when you want the weight gain to happen right away, for example during a diet. Otherwise it mainly increases the risk of stomach discomfort.

Do you need to take breaks from creatine?

No. The body's own creatine production decreases during use, but returns to normal after use stops. No permanent effect on the body's own creatine production has been found from long-term use, so based on the research evidence there's no need for cycling.

When should you take creatine?

When should you take creatine?

Timing makes practically no difference; what's decisive is the total daily dose. In one (small) meta-analysis, creatine taken after training added slightly more fat-free mass than creatine taken before training, but the difference was so small that it has no practical significance.

In practice, take creatine whenever you'll reliably remember it. For many people the easiest way is to take it with a daily meal or recovery drink.

What about coffee and creatine?

Ordinary coffee drinking isn't a problem. In a few studies, a large caffeine dose (about 5 mg/kg) during the loading phase weakened creatine's performance benefit.

In practice, ordinary coffee drinking doesn't need to be avoided. If you do a loading phase or take large caffeine doses (e.g. a pre-workout), it's worth taking them at a different time than creatine.

Which creatine should you buy?

Creatine monohydrate. Creatine monohydrate is the most common and most researched form of creatine, and over 95% of all creatine research has been done with monohydrate, and it's also the cheapest form.

In a systematic review by Fazio et al. (2021), no other form of creatine turned out to be more effective than monohydrate, even though the price was often almost double.

In practice, monohydrate fills the muscles' creatine stores just as well as the more expensive options. That's why the extra cost brings no added benefit based on the research evidence.

Purity, origin and Creapure

Commercial creatine is made synthetically, so the supplement itself is the same regardless of the country of manufacture. The differences arise from the purification process and quality control.

These days most well-known manufacturers reach over 99% purity. The German Creapure is the best-known quality standard, with a purity typically above 99.95%, but it isn't the only quality option.

The country of manufacture in itself tells you little — more important are the manufacturer's quality systems (e.g. GMP), third-party testing, and a good reputation.

Shopping list:

• Creatine monohydrate

• A well-known manufacturer, purity at least 99%

• GMP manufacturing

• For competitive athletes, a third-party tested product (Informed Sport, Informed Choice, or NSF Certified for Sport), since using a low-quality product may contain impurities that are a doping risk.

Who does creatine work best for, and who not?

Creatine works better the lower your baseline creatine stores are. Two practical observations follow from this:

Vegetarians benefit more than average. Dietary creatine comes from meat and fish, so vegetarians start out with lower muscle creatine content and get a greater performance benefit from supplementation.

Some people benefit only a little or not at all: So-called non-responders make up an estimated 20–30%, and they're typically people whose creatine stores are already nearly full. So some clearly benefit, some may not benefit at all, and most fall somewhere in between. If you don't notice any weight gain or change in your performance during use, you may be among the group who doesn't need to use creatine.

How much does creatine increase strength? In studies, creatine increases maximal strength typically by about 5–8% more than strength training without creatine. The effect doesn't come from a single workout, but from being able to do slightly more quality training week after week. (https://pubmed.ncbi.nlm.nih.gov/39519498/) (Branch 2003).

Creatine is an add-on that can help, not the foundation

Creatine can give a benefit of a few percent. That's a good edge, but it's worth putting in proportion: your training program's total load, consistency, progression and exercise choices affect your results considerably more.

That's exactly why your training program should be in order before, or at the same time as, you optimise supplements. Individual volume, the right weights, and progression determine your long-term development. Doing this by hand week after week is laborious, and that's precisely what AITOFIT was built for.

AITOFIT is a Finnish AI training app developed by exercise scientists at the University of Jyväskylä that sets the weights, reps and set counts and takes care of the program's progression automatically. You can read more about it here. Over 5,400 users have given the app a rating of 4.9/5.

You can try AITOFIT free for 9 days without a credit card.

Frequently asked questions about creatine

What does creatine do in the body?

Creatine is stored in the muscles as phosphocreatine and acts as a fast energy source. It donates a phosphate group to ADP, and ATP is reformed almost immediately. The effect shows up especially in short, maximal efforts, such as a single heavy set at the gym. In practice, you last slightly longer in a set.

How much creatine should you take per day?

3–5 g of creatine monohydrate per day, every day, including rest days. Scaled to body weight, an effective dose is 0.04 g per kilogram. A daily dose below 3 g risks being ineffective — for example, 2 g per day for six months did not improve swimmers' performance at all.

Do you need to load creatine?

No, you don't. A loading phase (20–25 g/day for 5–7 days) fills the stores in about a week, whereas with a 3–5 g daily dose it takes 3–4 weeks. The end result is the same. Loading is mainly worthwhile when you want the benefit available quickly, or you're dieting and want the weight gain to happen all at once to keep weight tracking clear.

Is creatine harmful to the kidneys?

Not in healthy people. Creatine can raise the creatinine value in a blood test, but that doesn't mean kidney damage. Tell your doctor about your creatine use if your kidney values are being measured. If you have a kidney or liver condition, discuss its use with your doctor.

Does creatine cause hair loss?

No. The claim rests on one small 2009 study. The study didn't measure hair loss at all, and current research evidence doesn't support a link between creatine and hair loss.

Does creatine make you fat?

No. Creatine raises weight typically by 1–2 kg, but it's water that stores in the muscle cells along with the creatine. Creatine has no direct effect on fat mass. Moderate weight gain is in practice a sign that creatine is working for you.

Can you take creatine with coffee?

Ordinary coffee drinking isn't a problem. In a few studies, however, a large daily caffeine dose (about 5 mg/kg) during the loading phase has cancelled out creatine's benefits. The sensible approach is to keep caffeine moderate and take creatine at a different time than pre-workouts or large coffee doses.

Do you need to take breaks from creatine?

No, you don't. Your own creatine production decreases during use, but returns to normal after stopping. No permanent suppression has been found from long-term use, so there's no physiological basis for cycling.

Which creatine should you buy?

Choose creatine monohydrate. It's the most researched, cheapest and most effective form of creatine. Purity should be at least 99% and manufacturing GMP-certified. Creapure is the best-known quality standard, but not the only good option.

When should you take creatine?

Timing matters very little. The most important thing is to take 3–5 g of creatine monohydrate every day. Take it whenever you'll most reliably remember it, for example with a meal or around training.

How quickly does creatine start to work?

With a loading phase, the effects usually begin in about a week. Without loading, the muscles' creatine stores fill up in about 3–4 weeks, after which the performance benefit is practically the same.

Summary

Creatine monohydrate is one of the few supplements whose effectiveness has been demonstrated by strong research evidence and whose use is safe. Remember these points and maximise the benefits:

• 3–5 g of creatine monohydrate daily, including rest days.

• A loading phase isn't essential. It speeds up when the effect begins, but doesn't change the end result.

• Breaks aren't needed. The body's own creatine production returns to normal after use stops.

• The 1–2 kg weight gain is water, not fat.

• Stomach discomfort is the most common side effect, and it usually clears up by adjusting the dosing.

• Creatine does not damage the kidneys or liver of healthy people based on the research evidence.

• Choose creatine monohydrate. More expensive forms have not proven more effective.

• Creatine supports training, but doesn't replace a good training program.

Once your creatine intake is in order, make sure your training program is too, so you get every bit of benefit creatine offers for your results. Try AITOFIT free for 9 days — it adjusts the weights, reps, set counts and progression automatically to suit your development.

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Sources: Kreider et al. (2017), International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. Hall, Manetta & Tupper (2021), Creatine Supplementation: An Update. Current Sports Medicine Reports. Jäger et al. (2011), Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids. Fazio et al. (2021), Efficacy of Alternative Forms of Creatine Supplementation on Improving Performance and Body Composition in Healthy Subjects: A Systematic Review. Journal of Strength and Conditioning Research. Neto et al. (2018), Effects of Low-Dose Creatine Monohydrate on Muscle Strength and Endurance. Asian Journal of Sports Medicine. Harris, Söderlund & Hultman (1992), Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clinical Science. Branch (2003), Effect of Creatine Supplementation on Body Composition and Performance: A Meta-Analysis. International Journal of Sport Nutrition and Exercise Metabolism. Forbes et al. (2021), Meta-Analysis Examining the Importance of Creatine Ingestion Strategies on Lean Tissue Mass and Strength in Older Adults. Nutrients. Forbes et al. (2022), Effects of Creatine Supplementation on Properties of Muscle, Bone, and Brain Function in Older Adults: A Narrative Review. Journal of Dietary Supplements. Roschel et al. (2021), Creatine Supplementation and Brain Health. Nutrients. Candow et al. (2022), Creatine O'Clock: Does Timing of Ingestion Really Influence Muscle Mass and Performance? Frontiers in Sports and Active Living. van der Merwe et al. (2009), Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine. Vandenberghe et al. (1996), Caffeine counteracts the ergogenic action of muscle creatine loading. Journal of Applied Physiology. Hespel et al. (2002), Opposite actions of caffeine and creatine on muscle relaxation time in humans. Journal of Applied Physiology. Ostojic & Ahmetovic (2008), Gastrointestinal distress after creatine supplementation in athletes. Research in Sports Medicine. Ilander, O. et al. (2021), Liikuntaravitsemus 3.0. VK-Kustannus Oy.

Author: Julius Granlund, MSc in Sport Science, University of Jyväskylä | Reviewed by: Tapio Tulenheimo, MSc in Sport Science, University of Jyväskylä