Sep 30, 2025

The Ultimate Scientific Guide to Creatine

What it is, how it works, who benefits, how to dose, what to avoid, and how to read the evidence.

Executive summary

Creatine monohydrate is one of the most studied performance and health supplements. The core mechanism is simple. Supplemental creatine increases intramuscular and cerebral phosphocreatine which buffers adenosine triphosphate during high energy demand. The ergogenic benefits for short and repeated high intensity work are robust. Strength and muscle accretion are consistently improved when creatine is paired with resistance training. Safety in healthy adults is strong across decades of trials and position stands. Kidney concerns remain common in popular media but are not supported by high quality evidence in healthy individuals. Beyond performance there is growing interest in cognition, mood, aging, glucose control, injury resilience and head trauma recovery. These non performance domains are promising but still heterogenous, with the most consistent effects in people who start with lower creatine availability such as vegetarians and during sleep loss or other energetic stressors. The form that carries the best data is creatine monohydrate. Most other marketed forms are not superior on bioavailability or outcomes. Taylor & Francis Online+1

What creatine is and how the phosphagen system works

Creatine is a guanidino compound synthesized from arginine and glycine and obtained in small amounts from meat and fish. In muscle and brain the creatine kinase system maintains energy homeostasis by shuttling high energy phosphates from sites of production to sites of use. Supplemental creatine increases total creatine pools which raises phosphocreatine availability. That enlarges the immediate buffer for adenosine triphosphate resynthesis during intense contractions and improves recovery between efforts. These effects explain the repeatedly observed increases in maximal strength, power output, and total training volume over weeks and months. The International Society of Sports Nutrition has repeatedly concluded that creatine monohydrate is effective and well supported for these use cases. PMC+1

At the cellular level creatine increases cell hydration which may act as an anabolic signal that supports protein synthesis and satellite cell activation over time. In practice the largest performance gains occur when creatine is paired with structured resistance training that delivers sufficient mechanical tension and progressive overload. PMC+1

What the strongest sport performance evidence shows

A large body of randomized trials and meta analyses demonstrates that creatine monohydrate increases one repetition maximum strength, repeated sprint capacity, and lean mass when combined with resistance training across ages and training statuses. The effects are most pronounced for repeated high intensity efforts under sixty seconds and for compound lifts where training volume increases drive hypertrophy. Taylor & Francis Online+1

In younger adults the signal is substantial for strength at both upper and lower body with meaningful improvements in training efficiency. In older adults who resistance train creatine raises lean tissue and strength compared with training alone which is clinically relevant for preserving function. Recent summaries and meta analyses reinforce this practical advantage for aging populations while noting that creatine without training does little for strength. The Washington Post+1

Concerns about cramping, dehydration or heat illness have not been borne out in well designed field studies. In division one football players those who used creatine actually reported fewer cramps, less heat illness and fewer missed practices. Mechanistically creatine increases intracellular water rather than extracellular edema and does not impair thermoregulation when programs are properly hydrated. PubMed+1

Cognitive and brain health effects

Creatine crosses the blood brain barrier through the SLC6A8 transporter and can raise brain creatine levels in humans. Cognitive benefits appear under conditions where energetic stress or low baseline creatine make the brain more sensitive to phosphagen support. Meta analytic work and recent trials suggest small to moderate improvements in memory, attention and processing speed especially during sleep deprivation and in vegetarians who start with lower stores. Effects are inconsistent in well rested omnivores which likely reflects ceiling effects and task selection. BioMed Central+2PMC+2

There is early clinical interest in mood disorders. A randomized double blind trial in women found that creatine added to an SSRI accelerated and enhanced antidepressant response with associated neuroimaging changes. Reviews in 2024 describe reductions in depressive symptoms when creatine augments standard therapy while calling for larger sex balanced trials. PMC+1

Traumatic brain injury and post concussion recovery are active research areas. Small pediatric trials and narrative reviews suggest that creatine given soon after injury may improve symptoms and reduce complications, consistent with animal data showing neuroprotection from improved cellular energy buffering. Military and civilian research groups are now running modern trials to define who benefits and when. Until those results mature creatine should not be presented as a proven treatment but as a plausible adjunct with a favorable safety profile in healthy people. PubMed+2NCBI+2

Metabolic health and glucose control

Creatine may augment post exercise glycogen supercompensation and has mechanistic links to glucose transport through greater GLUT4 recruitment. In type 2 diabetes a double blind trial reported improved glycemic control when creatine was combined with structured exercise. Larger and longer studies are needed but the direction of effect aligns with mechanistic expectations and with small recent trials. For athletes the practical utility is that creatine loading during high volume training blocks can support glycogen restoration and the ability to repeat quality work. PMC+2PubMed+2

Safety profile and kidney health

The persistent belief that creatine damages kidneys is not supported in healthy populations. In controlled trials and meta analyses creatine does not adversely affect measured kidney function. Serum creatinine often rises slightly because creatinine is the breakdown product of creatine. That laboratory change is expected and does not equate to reduced glomerular filtration in healthy people. Recent Mendelian randomization work further found no genetic association between creatine and kidney function. People with known kidney disease or those using nephrotoxic medications should consult their clinician before supplementing. Everyone should use third party tested creatine to reduce contamination risk. ScienceDirect+1

Gastrointestinal discomfort can occur with large single doses. Splitting doses and fully dissolving creatine in warm liquid mitigates symptoms for most users. Early transient weight gain of one to two kilograms reflects intracellular water and generally stabilizes within weeks. Field data in hot environments suggest creatine users are not at higher risk of heat illness when hydration is adequate. PMC+1

Hair loss concerns and hormones

A small study in male rugby players reported increased serum dihydrotestosterone during a short loading protocol. This result has not been replicated in subsequent work and modern trials do not show changes in dihydrotestosterone or hair parameters relative to placebo. Current evidence does not support the claim that creatine causes hair loss. PubMed+1

Who benefits most

People who begin with lower intramuscular creatine generally see larger gains. This includes many vegetarians and vegans and some endurance specialists. In cognition the largest effects have been observed during sleep loss or in vegetarians. Highly trained omnivores still benefit in the gym through greater training volume and strength when programs are well designed. Older adults who lift are consistent responders for strength and lean mass even when absolute changes are modest. Cambridge University Press & Assessment+2MDPI+2

Forms of creatine and what to buy

Creatine monohydrate remains the reference standard. It is stable, inexpensive, and essentially one hundred percent bioavailable. Studies comparing alternative forms such as hydrochloride, citrate, nitrate, buffered variants and ethyl ester do not show superiority for muscle creatine retention or performance. Ethyl ester in particular underperforms monohydrate. Choose plain creatine monohydrate powder from a brand that participates in independent testing such as NSF Certified for Sport or Informed Choice. PMC+2PMC+2

Creatine monohydrate remains the gold standard for efficacy, safety, and cost. Buffered creatine and several “novel” salts have not shown superior outcomes in head-to-head trials. Creatine hydrochloride and nitrate are more soluble and sometimes gentler on the stomach for a subset of users, but they have no clear performance advantages over monohydrate at matched doses. When in doubt, choose unflavored monohydrate with third-party testing. PMC+2PubMed+2

Practical mixing: Creatine dissolves better in warm liquid. It slowly degrades to creatinine in solution, especially with heat and time, so mix close to when you’ll drink it rather than leaving it in liquid for hours. This is a quality habit rather than a strict requirement. PMC

Dosing strategies and practical timing

Two validated paths exist to saturate muscle creatine.

Loading then maintenance
Twenty grams per day split into four five gram servings for five to seven days followed by three to five grams per day for maintenance. Larger or very muscular athletes can use approximately zero point one grams per kilogram per day for maintenance. This approach fills stores within one week.
No loading
Three to five grams per day without a loading phase. Full saturation occurs in roughly four weeks.

Co ingestion with carbohydrate and protein can increase muscle creatine retention through insulin mediated transporter activity. Alpha lipoic acid combined with creatine and a small amount of carbohydrate has also been shown to enhance intramuscular creatine in biopsy studies although this is not necessary for most users. The most important variable is consistency over weeks and months. Physiology Journals+2Physiology Journals+2

Caffeine
One small older study suggested that taking caffeine with creatine could blunt some ergogenic effects, while several later studies and reviews show mixed or neutral interactions. A practical compromise is to take creatine daily at any convenient time and keep pre workout caffeine timing based on performance tolerance without deliberately combining both in the same bolus. PubMed+1

Hydration
Creatine shifts water into the myocyte. Drink normally to thirst and match fluids to training needs. There is no requirement for excessive water intake. Field data in heat do not show increased heat illness among creatine users when standard hydration practices are followed. PubMed

Cycling
There is no physiological need to cycle creatine. Many athletes maintain a daily three to five gram dose year round and pause only when personal goals shift. The transporter does not appear to down regulate in a way that compromises pragmatic benefit during normal use. Taylor & Francis Online

Special populations and life stages

Women across the lifespan
Women often consume less dietary creatine and may begin with lower intramuscular stores. Resistance training plus creatine improves strength and lean mass in premenopausal and postmenopausal women, with emerging interest in potential cognitive and mood benefits. Current reviews emphasize the need for more sex specific trials while supporting routine use at typical doses in healthy women who train. PMC+1

Pregnancy
Human cohort work has mapped creatine metabolism during pregnancy and early trials are exploring dosing to define safe steady state plasma levels. Animal and mechanistic data suggest potential protective roles in placental and fetal energetics. This remains an investigational area. In practice pregnant people should not start creatine without clinical oversight until larger safety trials report. PubMed+1

Adolescents
Position statements note that creatine can be considered for post pubertal adolescents engaged in structured sport when diet is adequate and supplementation is supervised by qualified professionals. Emphasis remains on whole food nutrition and coaching before supplements. PMC

Vegetarians and vegans
Expect larger increases in muscle creatine and greater chances of cognitive benefit. Standard dosing applies. PubMed

Clinical conditions
Heritable creatine biosynthesis defects and creatine transporter deficiency are distinct medical entities where clinical protocols differ and should be managed by specialists. Over the counter supplementation for the general public does not treat these conditions. PMC+1

Choosing a product and avoiding pitfalls

Use creatine monohydrate powder with no additives. Micronized powder mixes more easily but does not change efficacy. PMC
Pick third party tested brands such as NSF Certified for Sport or Informed Choice to reduce contamination risk. This matters for all athletes who may be tested. Creatine is permitted under the World Anti Doping Code but contamination with prohibited stimulants is a general supplement risk. NPC Hello+1
Dissolve fully in warm water or any carbohydrate containing beverage if you prefer, and split larger doses across the day to reduce stomach upset.
Track what matters. Monitor body mass, training volume, one repetition maximum, sprint repeatability and for older adults simple function tests such as chair stands and timed up and go.

Protocols tailored to common training archetypes

Powerlifters, Olympic lifters, CrossFit and HYROX athletes

Dose: Load then maintain 3–5 g daily.
Timing: After training with protein and carbohydrate is convenient and may aid retention and adherence.
Why: Larger phosphocreatine stores support repeated high-output sets and reduce performance drop-off across sessions. This often enables more quality work, which is the true driver of adaptation. PubMed

Field and court athletes

Dose: 3–5 g daily in-season; consider 0.07–0.1 g/kg in a short loading week during pre-season.
Heat: No evidence of impaired thermoregulation with responsible hydration; monitor your body mass and fluid intake in hot camps. PMC

Endurance athletes with high-intensity demands

Dose: 3 g per day, slow-saturating.
Why: Benefits are clearest for repeated sprint and surges, track cycling pursuits, and finishing kicks. Test well before key races given potential mass changes. PubMed

Adults over 50 engaged in resistance training

Dose: 3–5 g per day; loading optional.
Why: Consistently improves lean mass and strength; bone outcomes are mixed but trending positive in some long trials. Pair with two to three days per week of progressive lifting. PMC+1

Vegetarians and vegans

Dose: Standard protocols; expect larger tissue creatine increases and possibly greater benefits on some outcomes. Ensure adequate total protein intake. PMC

Side effects and troubleshooting

GI upset during loading: Split doses, take with food, consider slow-saturating.
Water retention or “bloat”: Typically intracellular; reduce sodium swings and avoid loading if aesthetically sensitive.
Elevated serum creatinine on labs: Anticipated; ask your clinician to interpret within the supplementation context and, if needed, use cystatin C as a creatine-independent filtration marker. MDPI

Advanced notes for the curious

Caffeine co-use: Evidence is mixed; separate large caffeine doses from loading if concerned. PubMed+1
Brain claims: Meta-analyses show small benefits on memory and processing speed with heterogeneity; strongest signals occur under sleep deprivation or illness. Frontiers
Glucose homeostasis: Improvements in HbA1c with training in type 2 diabetes; by itself creatine is not a diabetes treatment. PubMed
Bone health: Mixed; do not rely on creatine alone for bone. Lift, get sufficient calcium and vitamin D, and load impact safely. PubMed
Form comparisons: Buffered and “alkaline” creatines do not outperform monohydrate in muscle creatine content or training outcomes. PMC

Practical checklist

Pick a third-party–certified creatine monohydrate.
Choose either: load then 3–5 g daily, or no load at 3–5 g daily.
Take with a mixed meal or post-training protein and carbohydrate.
Stay hydrated and track body mass; small increases are normal.
If labs show higher creatinine, contextualize with your clinician.
Reassess quarterly: keep if it improves training quality, recovery, or outcomes you care about.

Frequently asked questions grounded in evidence

Is creatine safe for my kidneys
In healthy adults randomized trials and meta analyses do not show harmful effects on kidney function. People with kidney disease should only use creatine under medical guidance. Rising creatinine on a lab test can reflect creatine breakdown rather than kidney damage. ScienceDirect

Will creatine make me puffy
Expect a rapid increase in intracellular water during loading followed by stabilization. This is not pathologic water retention and often supports training. PMC

Does creatine cause hair loss
There is no good evidence that creatine causes hair loss. One small study in rugby players reported an increase in dihydrotestosterone and has not been replicated. A modern randomized trial found no differences in dihydrotestosterone or hair metrics compared with placebo. PubMed+1

What about combining creatine and caffeine
Data are mixed. If you are concerned, separate daily creatine from your pre workout caffeine. Performance outcomes for most athletes are driven more by training quality than by timing these two precisely. PubMed+1

Is creatine legal in sport
Creatine is not on the World Anti Doping Agency Prohibited List. Choose third party tested products to reduce contamination risk. Wada-ama+1

Does creatine cause hair loss?
There is no consistent clinical evidence that creatine causes hair loss. One small trial reported higher DHT after loading; later work did not replicate DHT changes or show hair effects. PubMed+1

Is creatine bad for your kidneys?
In healthy adults using studied doses, high-quality trials and reviews do not show kidney harm. Elevated serum creatinine during use reflects creatine turnover, not necessarily renal dysfunction. People with kidney disease should consult a clinician. PMC+1

What form should I buy?
Creatine monohydrate is the most studied, effective, and economical form; buffered and other variants have not shown superior performance. Choose third-party–tested products. PMC

What’s the best time to take it?
Total daily intake matters most. If you like routines, take it post-training with protein and carbohydrate. PMC

Can I take creatine with coffee?
Sometimes yes; data are mixed. If you notice GI issues or performance blunting when combining, separate them by a few hours. PubMed

Is it allowed in sport?
Yes. Creatine is not prohibited by WADA. Wada-ama

References (selected, open-access where possible)

International Society of Sports Nutrition position stand on creatine: safety, efficacy, applications. PubMed
NIH Office of Dietary Supplements fact sheet on exercise and performance aids. Office of Dietary Supplements
EFSA Scientific Panel opinion on creatine monohydrate safety. EFSA Journal
Creatine plus resistance training in older adults (trials and reviews). PMC+2PubMed+2
Cognition under sleep deprivation and meta-analysis in adults. Nature+1
Creatine and glycemic control in type 2 diabetes with exercise. PubMed
Heat tolerance and body water distribution. PMC+1
Buffered creatine not superior to monohydrate. PMC
Carbohydrate or protein co-ingestion enhances creatine retention. Physiology Journals
Caffeine–creatine interaction: early trial and systematic review. PubMed+1
WADA status and supplement certification. Wada-ama+1