Creatine is probably the most studied sports supplement in existence. About 40% of athletes use it at some point, and it’s one of the few supplements where the research actually backs up most of the marketing claims. That’s unusual in the supplement world.

I’ve gone through the clinical evidence to separate what creatine can realistically do from the exaggerated claims. The short version: it works well for strength and power output, has some interesting cognitive effects, but isn’t a magic solution for everything people claim.

What is creatine?

Creatine is a compound your body makes naturally from three amino acids: arginine, glycine, and methionine. Your liver, pancreas, and kidneys produce it, and you also get some from eating meat and fish.

About 95% of your body’s creatine sits in skeletal muscle. The remaining 5% is in your brain, liver, testicles, and kidneys. Within muscle cells, roughly 60% exists in a phosphorylated form (phosphocreatine) and 40% as free creatine.

The phosphocreatine part matters for exercise. During short, intense efforts, your muscles burn through ATP (the energy currency) faster than your body can regenerate it through normal metabolism. Phosphocreatine acts as a rapid backup, donating its phosphate group to quickly regenerate ATP. This is why creatine supplementation targets high-intensity, short-duration activities rather than endurance exercise.

People started taking creatine supplements widely after the 1992 Barcelona Olympics, when several athletes attributed their success to it. Since then, it’s become one of the best-researched sports supplements available.

Benefits with good evidence

1. Improved strength and power output

This is creatine’s strongest claim, and the evidence supports it.

A meta-analysis of 53 double-blind, randomised, placebo-controlled trials found that creatine improved upper body strength performance during short-duration exercise (under 3 minutes), particularly in bench press movements [1]. Another meta-analysis covering 60 randomised controlled trials showed similar improvements in lower body strength during squats and leg press exercises [2].

The mechanism makes sense: by increasing phosphocreatine stores in muscle, you can sustain high-intensity efforts for slightly longer and potentially squeeze out extra reps. The typical improvement in performance is around 10-20% during high-intensity, repetitive exercise.

A third meta-analysis of 9 double-blind randomised experiments confirmed improvements in anaerobic power specifically [3]. If you’re doing sprints, heavy lifting, or other explosive activities, creatine is likely to help.

My take: This is the one area where creatine delivers reliably. The effect size isn’t massive, but it’s consistent across dozens of studies. For strength training and power sports, it’s worth considering.

2. Increased lean mass in older adults

Sarcopenia (age-related muscle loss) is a real problem. You start losing muscle mass after about age 30, and the rate accelerates after 50. This isn’t just a cosmetic issue. Muscle loss increases fall risk, reduces mobility, and correlates with heart disease, cognitive decline, and loss of independence.

A meta-analysis covering 21 studies and 721 adults over 50 found that creatine supplementation combined with resistance training increased lean tissue mass and improved both chest press and leg press strength compared to resistance training alone [4]. The strength gains were significantly better than placebo.

The key phrase there is “combined with resistance training.” Creatine isn’t going to build muscle while you sit on the couch. It appears to enhance the adaptive response to training, helping muscles recover and grow more effectively.

My take: For older adults already doing resistance training, adding creatine seems sensible. It’s cheap, well-studied, and the risk profile is low. But don’t expect it to replace actual exercise.

3. Cognitive benefits under stress

This one surprised me. Creatine isn’t just for muscles; your brain uses it too.

A systematic review of 6 randomised clinical trials involving 281 healthy participants found that creatine improved short-term memory and measures of intelligence/reasoning [5]. The effects were most pronounced in people under stress or experiencing age-related cognitive decline.

The effects on other cognitive domains (long-term memory, attention, executive function, reaction time) remain unclear from the available evidence. Sample sizes have been small, and study designs vary considerably.

The proposed mechanism involves brain energy metabolism. Cognitive tasks, particularly challenging ones, require ATP. Creatine supplementation increases brain creatine stores (verified by MRS imaging studies), which may support energy availability during demanding mental tasks.

My take: The cognitive research is genuinely interesting but still preliminary. I wouldn’t take creatine primarily for brain benefits, but if you’re already using it for exercise, there may be a nice side effect. The evidence is stronger for people dealing with sleep deprivation or stress.

Benefits with weaker evidence

4. Bone density improvements

Osteoporosis affects millions of people, particularly post-menopausal women and older men. Hip fractures carry a significant mortality risk, and any intervention that genuinely improves bone density would be valuable.

Unfortunately, the evidence for creatine here is disappointing.

A meta-analysis of 5 randomised controlled trials involving 193 men over 50 or post-menopausal women found no significant improvement in bone mineral density at any site (whole body, hip, femoral neck, or lumbar spine) when creatine was combined with resistance training compared to resistance training alone [6].

The intervention periods ranged from 12 weeks to one year, with exercise frequency of 1.5 to 3 times per week. It’s possible that longer trials might show different results, but so far the data doesn’t support using creatine specifically for bone health.

My take: Don’t take creatine expecting it to help your bones. Resistance training itself does help bone density; the creatine addition doesn’t appear to add much.

5. Chronic obstructive pulmonary disease (COPD)

COPD patients often have muscle weakness as a complication, which worsens their exercise tolerance and quality of life. The theory was that creatine might help these patients maintain muscle function during pulmonary rehabilitation programmes.

A systematic review and meta-analysis of 4 randomised controlled trials covering 151 COPD patients found no significant effect of creatine supplementation on exercise capacity, muscle strength, or health-related quality of life [7].

The sample sizes were small, and it’s possible that certain subgroups might benefit, but the current evidence doesn’t support recommending creatine for COPD patients.

My take: Skip this one. There are better-supported interventions for COPD patients.

6. Reducing sleep deprivation effects

Sleep deprivation impairs mood, balance, and cognitive function. Part of this may relate to decreased brain creatine levels (your brain works hard even when sleep-deprived, burning through energy stores).

A randomised, double-blind, placebo-controlled study found that creatine supplementation reduced the impairment of mood, balance, and cognitive function associated with sleep deprivation [8].

This is interesting but limited. One study isn’t enough to draw strong conclusions, and it doesn’t mean creatine can replace proper sleep. However, for people who occasionally face unavoidable sleep restriction (shift workers, new parents, travellers), it might help take the edge off.

My take: Intriguing but preliminary. Get more sleep if you can. If you can’t, creatine might help slightly with the cognitive fallout.

Side effects and safety

The good news: creatine has an excellent safety profile for most healthy people taking appropriate doses.

A 21-month study that monitored 52 blood and urine biochemical markers in creatine users found no abnormal adverse reactions [9]. This is unusually thorough follow-up for a supplement study.

The Mayo Clinic notes that creatine is “likely safe” when used at appropriate doses, though they recommend checking with a doctor if you have kidney concerns.

Common but generally mild side effects include:

Weight gain from water retention in muscles (this is expected, not harmful)
Stomach discomfort, especially at high doses
Muscle cramps (more common during loading phases)
Diarrhoea
Nausea
Dizziness

These issues are more common when people take too much at once. Spreading doses throughout the day and ensuring adequate hydration helps.

The NHS guidance on supplements recommends getting nutrients from food where possible, but acknowledges that creatine is one of the better-studied sports supplements available.

Safety precautions (5 contraindications)

Pregnancy and breastfeeding: There’s insufficient safety data. Avoid it.
Bipolar disorder: Some case reports suggest creatine may worsen manic symptoms. If you have bipolar disorder, discuss with your psychiatrist before using creatine.
Kidney disease: Creatine is processed by the kidneys, and the breakdown product creatinine is used as a marker of kidney function. People with existing kidney problems should avoid creatine or use it only under medical supervision. Healthy kidneys handle it fine; damaged kidneys may not.
Parkinson’s disease with caffeine use: One study found that the combination of creatine and caffeine might accelerate disease progression in Parkinson’s patients. If you have Parkinson’s and want to try creatine, avoid taking caffeine at the same time.
Nephrotoxic medications: Combining creatine with drugs that stress the kidneys may increase the risk of kidney damage. Common nephrotoxic drugs include:
- Cyclosporine
- Aminoglycoside antibiotics (amikacin, gentamicin, tobramycin)
- NSAIDs (ibuprofen, indomethacin, naproxen, piroxicam)

If you’re taking any of these medications regularly, talk to your doctor before adding creatine.

Dosing guidelines

The classic approach uses a loading phase followed by maintenance:

Loading phase (optional): 0.3 grams per kilogram of body weight daily for 5-7 days, split into 4 doses. For a 70 kg person, that’s about 20 grams per day (5 grams four times daily). This rapidly saturates muscle creatine stores.

Maintenance phase: 0.03 grams per kilogram daily, or simply 3-5 grams per day. For a 70 kg person, about 2-5 grams daily maintains elevated creatine levels.

Alternative: skip the loading phase. Taking 3-5 grams daily without loading will eventually achieve the same muscle creatine levels; it just takes 3-4 weeks instead of one week. Some people prefer this approach because it causes less gastrointestinal discomfort.

Creatine monohydrate is the most studied form and typically the cheapest. Fancier versions (creatine ethyl ester, buffered creatine, etc.) haven’t shown advantages in studies despite higher prices.

Take creatine with food and plenty of water. Timing doesn’t appear to matter much, though some research suggests post-workout may be slightly better for muscle uptake.

11 benefits and side effects of arginine - another amino acid popular with athletes
5 benefits and side effects of taurine - often combined with creatine in pre-workout supplements
13 effects of CoQ10 - another compound involved in cellular energy production

References

Lanhers C, et al. Creatine supplementation and upper limb strength performance: A systematic review and meta-analysis. Sports Med. 2017;47(1):163-173. PubMed
Lanhers C, et al. Creatine supplementation and lower limb strength performance: A systematic review and meta-analyses. Sports Med. 2015;45(9):1285-1294. PubMed
Mielgo-Ayuso J, et al. Effects of creatine supplementation on athletic performance in soccer players: A systematic review and meta-analysis. Nutrients. 2019;11(4):757. PubMed
Chilibeck PD, et al. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: A meta-analysis. Open Access J Sports Med. 2017;8:213-226. PubMed
Avgerinos KI, et al. Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trials. Exp Gerontol. 2018;108:166-173. PubMed
Forbes SC, et al. Effect of creatine supplementation during resistance training on bone mineral density in older adults: A meta-analysis. J Nutr Health Aging. 2018;22(6):750-757. PubMed
Fuld JP, et al. Creatine supplementation during pulmonary rehabilitation in chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2010;(1):CD006631. PubMed
McMorris T, et al. Effect of creatine supplementation and sleep deprivation, with mild exercise, on cognitive and psychomotor performance, mood state, and plasma concentrations of catecholamines and cortisol. Psychopharmacology (Berl). 2006;185(1):93-103. PubMed
Kreider RB, et al. Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Mol Cell Biochem. 2003;244(1-2):95-104. PubMed