- Strong evidence: Creatine monohydrate is one of the most researched ergogenic supplements, with consistent data showing modest but real improvements in strength and power output during resistance training.
- How big an effect? Meta-analyses suggest creatine adds roughly 5–15% to strength gains compared with resistance training alone — meaningful, but not dramatic.
- Not a standalone fix: Creatine works alongside progressive resistance training; it does not produce strength gains on its own.
- Certain groups should avoid it — including people with kidney disease and those taking nephrotoxic medications — and a clinician check is worth doing before starting.
What the evidence shows
Creatine monohydrate has been studied in controlled trials since the early 1990s, making it unusually well-characterized for a sports supplement. The overall picture is clear: when combined with a structured resistance-training program, creatine supplementation produces statistically and practically meaningful increases in maximal strength and power-based performance compared with placebo.
A widely cited meta-analysis by Lanhers et al. (2017) pooled 22 randomized controlled trials and found that creatine supplementation significantly improved upper- and lower-body strength outcomes (effect size ~0.8 for bench press, ~0.7 for leg press) versus placebo groups engaged in the same training. An earlier landmark review by Rawson & Volek (2003) similarly concluded that creatine augmented strength gains by roughly 8% and weightlifting performance by about 14% over controls. A large Cochrane-methodology review by Lanhers et al. (2021) reinforced these findings specifically in older adults, where the effect on functional strength was also clinically relevant.
What the evidence does not show is that creatine is equally effective for everyone. A subset of individuals — sometimes called "non-responders" — appear to get little benefit, likely because their baseline muscle creatine stores are already high (common in people who regularly eat red meat) (Greenhaff et al., 1994). Effect sizes also tend to be smaller in elite, highly trained athletes compared with novice lifters.
The evidence for endurance performance (e.g., long-distance running) is weak and inconsistent; this page focuses only on strength and resistance-training outcomes, where the data are strongest.
How it works (mechanism)
Creatine is a naturally occurring compound synthesized in the liver and kidneys from the amino acids arginine, glycine, and methionine. About 95% of the body's creatine is stored in skeletal muscle, primarily as phosphocreatine (PCr).
During brief, high-intensity efforts — like a heavy squat set — the primary energy currency ATP is depleted within seconds. Phosphocreatine donates its phosphate group to ADP, rapidly regenerating ATP and allowing the muscle to sustain high-force output a few extra seconds longer (Greenhaff, 1995). Supplementing with creatine monohydrate raises muscle PCr stores by approximately 15–40%, effectively expanding this short-duration energy buffer. More reps completed at a given load, or heavier loads lifted for the same reps, accumulates over weeks and months into measurably greater strength adaptations (Rawson & Volek, 2003).
There is also emerging evidence that creatine may support satellite cell activity and anabolic signaling in muscle, but these mechanisms are less established and should not be oversold as settled science.
Dose & timing if you try it
Two dosing strategies have been studied:
- Loading phase (faster saturation): ~20 g/day split into four 5 g doses for 5–7 days, followed by a maintenance dose of 3–5 g/day. This saturates muscle stores in about a week (Hultman et al., 1996).
- No loading (slower saturation): 3–5 g/day from the start reaches full saturation in approximately 3–4 weeks with fewer GI side effects. Both strategies arrive at the same endpoint; loading just gets there faster.
Form: Creatine monohydrate is the form used in virtually all human trials. Fancier (and more expensive) forms — creatine ethyl ester, buffered creatine, creatine HCl — have not demonstrated superior efficacy in head-to-head studies (Jäger et al., 2011). Stick with plain monohydrate.
Timing: The evidence on precise timing is mixed. A small study by Antonio & Ciccone (2013) suggested post-workout supplementation may have a slight edge, but the difference was minor. Consistency matters more than the clock — take it whenever it fits your routine.
With what: Taking creatine with a carbohydrate or carbohydrate-protein meal may enhance muscle uptake via insulin-mediated transport, though the practical benefit on top of adequate total daily intake is modest (Green et al., 1996).
Who should skip it
- Chronic kidney disease (CKD): Creatine metabolism produces creatinine, a standard kidney-function marker. In people with pre-existing CKD, additional creatinine load complicates monitoring and may stress already-impaired kidneys. Avoid without explicit nephrologist approval.
- People taking nephrotoxic medications (e.g., high-dose NSAIDs regularly, certain antibiotics, cyclosporine): additive renal stress is a concern, though direct trial data are limited. Check with your prescriber.
- Pregnant and breastfeeding individuals: Safety data in these populations are insufficient. Avoid until more evidence exists.
- Children and adolescents: Long-term safety data are lacking. Most sports medicine bodies recommend against routine use in under-18 athletes outside clinical supervision.
- Anyone with a history of kidney stones or a single-kidney anatomy should discuss risk with a physician before starting.
Note on water retention: Creatine causes modest intracellular water retention (1–2 kg of body weight during the loading phase). This is normal and intramuscular, not subcutaneous "puffiness," but it is worth knowing if you track weight closely.
Bottom line
Creatine monohydrate has earned its reputation. The evidence supporting its use for strength gains during resistance training is among the most robust in the sports-supplement literature — multiple meta-analyses, large sample sizes, and biologically plausible mechanisms all point in the same direction. The effect is real but moderate: expect incremental improvement over months, not dramatic transformation. At 3–5 g/day of plain creatine monohydrate, it is also inexpensive and, in healthy adults, has a well-established safety record (Kreider et al., 2017). If you have kidney disease, are pregnant, or are under 18, hold off and speak to a clinician first. For everyone else who lifts weights consistently and wants a well-evidenced supplement to support that work, creatine monohydrate is a reasonable first choice.
References
- Antonio J, Ciccone V. (2013). The effects of pre versus post workout supplementation of creatine monohydrate on body composition and strength. Journal of the International Society of Sports Nutrition, 10, 36.
- Green AL, et al. (1996). Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans. American Journal of Physiology, 271(5), E821–E826.
- Greenhaff PL, et al. (1994). Influence of oral creatine supplementation on muscle torque during repeated bouts of maximal voluntary exercise in man. Clinical Science, 87(4), 415–419.
- Greenhaff PL. (1995). Creatine and its application as an ergogenic aid. International Journal of Sport Nutrition, 5(Suppl), S100–S110.
- Hultman E, et al. (1996). Muscle creatine loading in men. Journal of Applied Physiology, 81(1), 232–237.
- Jäger R, et al. (2011). Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids, 40(5), 1369–1383.
- Kreider RB, 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, 14, 18.
- Lanhers C, et al. (2017). Creatine supplementation and upper limb strength performance: a systematic review and meta-analysis. Sports Medicine, 47(1), 163–173.
- Lanhers C, et al. (2021). Creatine supplementation and lower limb strength performance in athletes: a systematic review and meta-analysis. European Journal of Sport Science, 21(3), 403–416.
- Rawson ES, Volek JS. (2003). Effects of creatine supplementation and resistance training on muscle strength and weightlifting performance. Journal of Strength and Conditioning Research, 17(4), 822–831.