Does creatine help with brain fog?

Nobody has tested it on brain fog itself, because no trial uses that as an outcome. The closest evidence is memory. A meta-analysis of 16 randomized trials in 492 adults found creatine gave a small improvement in memory, a standardized difference of 0.31, on moderate certainty evidence. The same analysis found no improvement in overall thinking or in executive function. A separate analysis of 8 trials in healthy people found the memory gain larger in adults aged 66 to 76 and absent in people aged 11 to 31.

Unsettled. Brain fog is a complaint, not a measurement. The trials measured memory, fatigue and test scores, mostly in healthy people, and the most relevant trial for people who feel foggy after an illness had five people per group. What we can say is narrow: a small memory effect on pooled data, and short-term protection under sleep loss in a few small trials.

What the trials found

Memory and general thinking

The 16-trial analysis pooled adults aged about 21 to 76, healthy and with specific diseases, all taking creatine monohydrate. The memory effect of 0.31 had a confidence interval from 0.18 to 0.44. A 2025 correction to the paper changed wording about attention and processing speed and left the memory numbers unchanged. For overall cognitive function and executive function there was no significant improvement, and the reviewers rated that evidence low certainty.

A separate meta-analysis of 8 placebo-controlled trials in healthy people split them by age. Adults aged 66 to 76 improved by 0.88 (95% CI 0.22 to 1.55), with heterogeneity of 83% across those few trials. People aged 11 to 31 improved by 0.03, which is no measurable effect. A review of six studies in 1,542 adults aged 55 and over found five reporting a positive link with memory or attention. Only two of those six were trials, and only one rated good quality, so it adds little to the pooled trials.

In rested young adults the trials are flat. Twenty-two people aged about 21 took a low dose of 0.03 g per kg a day, about 2 g, for six weeks and showed no change on any of seven cognitive tests against placebo. A systematic review of how creatine reaches the brain found it raises brain creatine only to a limited extent and called the results on cognition somewhat equivocal.

Under sleep loss

This is where the sharpest results sit, and every trial is small. In 15 healthy adults aged 20 to 28 kept awake for 21 hours, one dose of 0.35 g per kg cut self-rated fatigue by 8 ± 7% against placebo. That dose is about 25 g for a 154 lb (70 kg) adult, far above the 3 to 5 g a day people usually take. The same group then gave 29 healthy adults a lower single dose of 0.2 g per kg and reported up to 12% less decline on cognitive tests during 21 hours awake.

An older trial in men gave 20 g a day for seven days before 18 to 36 hours without sleep, with exercise. Only one complex executive task improved, and only at 36 hours. Short-term memory, reaction time, balance and mood did not differ. The abstract does not give the sample size.

Mental fatigue from a long task

In a crossover trial of 14 healthy adults aged about 24, seven days of 20 g creatine a day did not prevent the slowdown caused by a 90-minute mentally tiring task. Response speed fell 4.4% and Flanker accuracy fell 5.0% on both creatine and placebo. Stroop accuracy was 4.9% better on creatine, and motivation and vigor were lower on it.

After COVID

One pilot randomized trial enrolled 15 adults with long COVID and moderate fatigue, five per group, for eight weeks of 8 g creatine a day, with or without 3 g of glucose, against placebo. In the creatine plus glucose group, self-reported difficulty concentrating fell with an effect size of 0.80. The symptoms were self-reported and the benefit showed in the group that also took glucose. It is the closest thing to a brain fog trial we found, and it needs repeating at a real size.

Who should be careful

The safety evidence here comes from healthy people and from women in general trials. We have no cards on children, on people with existing kidney disease or on interactions with medicines, so this page cannot speak for those groups.

In the trial of a single 0.2 g per kg dose in 29 adults, creatine was well tolerated, with no reports of stomach upset or other physical side effects. That covers one dose on one night and says nothing about months of use. Across 29 studies with 951 women, no study reported a significant difference in measures of kidney or liver function, and side effects were often poorly reported in those trials.

Creatine nudges the blood creatinine reading up. A meta-analysis pooling 177 people on creatine and 263 controls found a slight rise in serum creatinine with no significant change in kidney filtration rate. Anyone having kidney blood tests should mention creatine, because the result can look worse than kidney function is.

Not for everyone. Pregnancy is untested. A Cochrane review searching to November 2014 found no randomized trials of creatine in pregnant women. If you are pregnant or have kidney disease, the trials here do not cover you, and creatine is a question for the person treating you.

What expert bodies say

The European Union did not authorize claims that creatine improves mental attentiveness, concentration or mental performance, and it did not authorize the claim that it improves mental attentiveness in the elderly. A rejected claim means the evidence did not meet the bar when it was assessed. It does not mean there is no effect. We found no position from a US or European expert body on creatine for memory or brain fog.

How we searched

What would change this answer

• Adequately powered randomized trials in long COVID or chronic fatigue syndrome with cognitive outcomes. The pilot above had five people per group, and the local copy of ClinicalTrials.gov had no registered trial of creatine with a cognition, fatigue or long COVID outcome.
• A trial in older adults large enough to settle the age split. The 0.88 estimate comes from a handful of trials with high heterogeneity.
• Repeats of the sleep loss trials by a second group, at ordinary daily doses rather than single high doses.

More on creatine itself, including food sources and the muscle evidence: Creatine.

Sources

1. ev-crbf-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 492
   Creatine supplementation showed significant positive effects on memory (SMD = 0.31, 95% CI: 0.18-0.44, Hedges's g = 0.3003, 95% CI: 0.1778-0.4228)
   
   Who: adults aged 20.8-76.4 years, healthy and with specific diseases, 16 RCTs of creatine monohydrate
   Effect: memory SMD 0.31 (95% CI 0.18 to 0.44); GRADE moderate
   Certainty: corrigendum 2025 (PMC11873458) only rewords attention and processing speed paragraphs; memory unchanged
   Front Nutr, 2024 · checked 2026-10-07 · we read the abstract
2. ev-crbf-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 492
   However, no significant improvements were found on overall cognitive function or executive function.
   
   Who: adults in 16 RCTs of creatine monohydrate
   Effect: overall cognition and executive function not significantly improved; GRADE low
   Certainty: no trial measured brain fog as an outcome
   Front Nutr, 2024 · checked 2026-10-07 · we read the abstract
3. ev-crbf-03 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 8 trials
   Subgroup analyses revealed a significant improvement in memory in older adults (66-76 years) (SMD = 0.88; 95%CI, 0.22-1.55; I2 = 83%; P = 0.009) compared with their younger counterparts (11-31 years) (SMD = 0.03; 95%CI, -0.14 to 0.20; I2 = 0%; P = 0.72).
   
   Who: healthy individuals in placebo-controlled RCTs, older adults 66-76 years vs younger 11-31 years
   Effect: older SMD 0.88 (95% CI 0.22 to 1.55), I2 83%; younger SMD 0.03 (95% CI -0.14 to 0.20)
   Certainty: high heterogeneity in the older subgroup; few trials
   Nutr Rev, 2023 · checked 2026-10-07 · we read the abstract
4. ev-crbf-04 · Randomized controlled trial(s) · randomized placebo-controlled trial, sessions in random order · n = 15
   Creatine significantly reduced fatigue in terms of FAT by 8 ± 7% (Wilcoxon’s Z26 = − 2.84, p = 0.002) at 2 a.m. and 4 a.m. pooled.
   
   Who: 15 healthy subjects aged 20-28, 8 women, single dose 0.35 g/kg creatine monohydrate or placebo during 21 h sleep deprivation
   Effect: fatigue score reduced 8 +/- 7% vs placebo at 2 and 4 a.m.
   Certainty: very small sample; dose about 25 g for 154 lb (70 kg), far above usual 3-5 g/d
   Scientific Reports, 2024 (Gordji-Nejad et al.) · checked 2026-10-07 · we read the fulltext
5. ev-crbf-05 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = 29
   Although the effect is less pronounced than with a high dose of 0.35 g/kg, there is still an improvement of up to 12%.
   
   Who: 29 healthy subjects, single dose 0.2 g/kg creatine monohydrate or placebo during 21 h sleep deprivation
   Effect: up to 12% less deterioration; smaller than with 0.35 g/kg
   Certainty: small; same group as the 0.35 g/kg study
   Nutrients, 2026 · checked 2026-10-07 · we read the abstract
6. ev-crbf-06 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = —
   It was concluded that, during sleep deprivation with moderate-intensity exercise, creatine supplementation only affects performance of complex central executive tasks.
   
   Who: men, 5 g creatine monohydrate four times a day for 7 days, then 18-36 h sleep deprivation with exercise
   Effect: better central executive task at 36 h only; no difference in short-term memory, reaction time, balance or mood
   Certainty: sample size not given in abstract
   Physiol Behav, 2007 · checked 2026-10-07 · we read the abstract
7. ev-crbf-07 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = 22
   These results suggest that six weeks of creatine supplementation (0.03/g/kg/day) does not improve cognitive processing in non-sleep deprived young adults.
   
   Who: 22 young adults aged about 21, 0.03 g/kg/day creatine or placebo for 6 weeks, not sleep deprived
   Effect: no group, time or interaction effects on reaction time, memory, reasoning or math processing (all p>0.05)
   Certainty: low dose (about 2 g/d); small
   Physiol Behav, 2008 · checked 2026-10-07 · we read the abstract
8. ev-crbf-08 · Randomized controlled trial(s) · randomized double-blind placebo-controlled crossover trial · n = 14
   CONCLUSION: Creatine supplementation improved physical (strength endurance) and prolonged cognitive (Stroop accuracy) performance, yet it did not combat MF-induced impairments in short sport-specific psychomotor or cognitive (Flanker) performance.
   
   Who: 14 healthy adults aged about 24, 20 g/day creatine or placebo for 7 days, crossover
   Effect: mental fatigue still slowed visuomotor response 4.4% and cut Flanker accuracy 5.0% in both conditions; Stroop accuracy +4.9% with creatine
   Certainty: small crossover; motivation and vigor were lower on creatine
   Med Sci Sports Exerc, 2020 · checked 2026-10-07 · we read the abstract
9. ev-crbf-09 · Randomized controlled trial(s) · randomized double-blind placebo-controlled parallel-group trial · n = 15
   Several long COVID symptoms (including body aches, breathing problems, difficulties concentrating, headache, and general malaise) were significantly reduced in creatine-glucose group at 8-wk follow-up (p≤0.05); the effect sizes for reducing body aches, difficulties concentrating, and headache were 1.33, 0.80, and 1.12, respectively, suggesting a large effect of creatine-glucose mixture for these outcomes.
   
   Who: 15 adults with long COVID and moderate fatigue, 8 g/day creatine monohydrate with or without 3 g glucose vs placebo for 8 weeks
   Effect: difficulties concentrating effect size 0.80 in creatine-glucose group (p<=0.05); body aches 1.33, headache 1.12
   Certainty: 5 per arm; self-reported symptoms; benefit seen in the creatine-glucose arm
   J Nutr Sci Vitaminol (Tokyo), 2024 · checked 2026-10-07 · we read the abstract
10. ev-crbf-10 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = 29
    Creatine supplementation was well tolerated, with no reports of gastrointestinal distress or other adverse physical symptoms.
    
    Who: 29 healthy adults, single dose 0.2 g/kg creatine monohydrate
    Effect: no gastrointestinal distress or other adverse physical symptoms reported
    Certainty: single dose, one night; says nothing about long-term use
    Nutrients, 2026 · checked 2026-10-07 · we read the fulltext
11. ev-crbf-11 · Meta-analysis or systematic review · systematic review and meta-analysis · n = 951
    No statistically significant difference was reported in measures of renal or hepatic function.
    
    Who: 951 female participants in 29 studies of creatine monohydrate that monitored adverse outcomes
    Effect: no significant difference in renal or hepatic function; no deaths or serious adverse outcomes
    Certainty: adverse events often poorly reported in included trials
    Nutrients, 2020 · checked 2026-10-07 · we read the abstract
12. ev-crbf-12 · Meta-analysis or systematic review · Cochrane systematic review of RCTs (empty review) · n = 0 trials
    We found no randomised controlled trials for inclusion in this review.
    
    Who: pregnant women, trials of creatine for fetal neuroprotection
    Effect: no completed or ongoing RCTs identified
    Certainty: search to November 2014; empty review
    Cochrane Database Syst Rev, 2014 · checked 2026-10-07 · we read the abstract
13. ev-crbf-13 · Position of an expert body · EU health claims register entry · n = —
    POL-HC-6995 Creatine Improves mental attentiveness also in the elderly Non-authorised
    
    Who: EU health claims register
    Effect: status non-authorized
    Certainty: Non-authorized means the evidence did not meet the bar at assessment, not that there is no effect.
    EU Register on nutrition and health claims, claim POL-HC-6995, snapshot 2026-09-21 · checked 2026-10-07 · we read the section
14. crtn-daily-r4-10 · Meta-analysis or systematic review · systematic review and meta-analysis · n = 440
    Creatine supplementation is associated with a modest, transient increase in serum creatinine levels, likely due to metabolic turnover rather than renal impairment. No significant changes were observed in GFR, suggesting preserved kidney function.
    
    Who: 21 studies reviewed, 12 pooled with 177 creatine and 263 control participants
    Effect: serum creatinine MD 0.07 (95% CI 0.01 to 0.12); GFR no significant difference
    Certainty: MD units in the abstract are doubtful (µmol/L); designs of the included studies are not only RCTs
    BMC Nephrol, 2025 · checked 2026-10-03 · we read the abstract
15. crtn-daily-r4-13 · Observational data · systematic review of trials and cross-sectional studies · n = 1542
    Five of the six (83.3%) studies reported a positive relationship between creatine and cognition in older adults, particularly in the domains of memory and attention. One study achieved a methodological quality rating of "good", two "fair", and three "poor".
    
    Who: 1542 adults aged 55 and over, 2 RCTs and 4 cross-sectional studies
    Effect: 5 of 6 studies positive (memory, attention); quality: 1 good, 2 fair, 3 poor
    Certainty: mostly observational data
    Nutr Rev, 2026 · checked 2026-10-03 · we read the abstract
16. crtn-daily-r4-14 · Observational data · systematic review · n = —
    The review supported claims that creatine supplementation can increases brain creatine content but also demonstrated somewhat equivocal results for effects on cognition.
    
    Who: studies of creatine supplementation and cognition
    Effect: brain creatine up to a limited extent; cognition results equivocal
    Certainty: no meta-analysis
    Behav Brain Res, 2024 · checked 2026-10-03 · we read the abstract
17. crtn-daily-r4-15 · Position of an expert body · regulatory decision · n = —
    POL-HC-6994 Creatine Improves mental attentiveness Improved powers of concentration and ability to absorb information Assists in mental performance Non-authorised
    
    Who: EU health claims register
    Effect: status non-authorized
    Certainty: reason for refusal is absent in the snapshot
    EU Register on nutrition and health claims, claim POL-HC-6994, snapshot 2026-09-21 · checked 2026-10-03 · we read the dataset