Do nootropics work? The benefits the evidence actually supports

"Nootropic" is a marketing umbrella, not a single substance, so the question has no single answer. Our guide What are nootropics? covers the definition. This page asks a narrower question: for each benefit people usually list, what did placebo-controlled trials in people actually find?

There is no shortcut through the category as a whole. As of November 11, 2026 we found no meta-analysis that pooled nootropics as one category in healthy adults (PubMed and Europe PMC searches, November 11, 2026). So every claim below is tied to one compound and one measured outcome.

Two ideas help in reading the numbers. A placebo is an identical-looking dummy, and a trial that compares the compound with one tells you what the compound adds beyond expectation. An effect size such as a standardized mean difference (SMD, or Hedges' g) expresses the gap between the two groups in standard-deviation units, so a value near zero means the groups performed about the same. Our guide How to read a supplement study goes further.

Each compound links to its monograph, which carries safety, interactions and legal status. Every grade badge comes from our evidence matrix, and how we grade evidence explains the letters.

The table takes nine benefits claimed for nootropics, from sharper focus and better memory to energy, calm, sleep and physical performance, and matches each one to the outcome trials measure and the compounds with the most relevant evidence on this site.

Table: Popular nootropic claims matched to graded outcomes

Ginkgo is often promoted for memory and focus, but in healthy people its effects were close to zero [15]. It has its own section below.

Two free factors move the same test scores that supplements are judged on. A meta-analysis of 70 articles covering 147 cognitive tests found effects of short-term total sleep deprivation that ranged from small and non-significant for reasoning accuracy to large for lapses in simple attention (g = -0.776) [1].

Exercise points the other way. A 2025 meta-review of 30 systematic reviews with meta-analyses (383 studies, 18,347 participants from children to older adults) found that a single bout of exercise improved cognitive function with a small-to-medium effect (mean SMD = 0.33) [2]. The benefit appeared for attention (mean SMD = 0.37), executive function (mean SMD = 0.36) and memory (mean SMD = 0.23), and exercise intensity, type and duration did not change it [2].

A 2025 meta-analysis pooled 31 randomized, double-blind, placebo-controlled trials in 1,455 rested healthy adults and found caffeine improved accuracy (g = 0.27) and reaction time (g = 0.28) on attention tests [3]. Doses of 200 mg or more improved both more than lower doses; reaction time kept improving as doses rose, while accuracy improved only up to a point and then declined [3]. The effect was not related to habitual caffeine intake or task complexity [3]. A 2005 review of controlled studies argued that in regular users much of the apparent benefit is reversal of withdrawal after a short break from caffeine, with tolerance developing to the acute effects [22], so the caffeine grade covers acute effects only.

In people short on sleep, a meta-analysis of 45 publications found caffeine improved accuracy on attention tests (g = 0.68) and executive function (g = 0.35) [4]. Those figures come from sleep-deprived or sleep-restricted people, not rested adults [4]. Caffeine's safety, its effect on sleep and its legal limits are on the caffeine monograph. More options for this goal are on our focus hub.

For ginkgo, the same outcome is null. A meta-analysis of randomized trials in healthy people found an attention effect of d = -0.08 (95% CI -0.21 to 0.02) across 910 participants, non-significant and close to zero [15]. A 2026 network meta-analysis of 29 trials in healthy adults also found no significant differences in sustained attention, selective attention or processing speed for ginkgo or bacopa [10].

L-theanine is an amino acid derived from green tea [5]. A 2026 meta-analysis of 31 randomized controlled trials in healthy and clinical populations (1,168 participants in all) found that a single 200 mg dose taken 30-60 minutes before testing improved choice reaction time compared with placebo (SMD = 0.51; 95% CI 0.25-0.77) [5]. One of its authors founded a company selling dietary supplements [5]. A 2025 meta-analysis, co-funded by Lipton Teas and Infusions and with authors employed by Lipton and Unilever, found a smaller effect of L-theanine alone on choice reaction time in the first hour (SMD -0.35, where a negative value favors theanine), and its authors noted that the confidence intervals frequently showed uncertainty about the direction and size of the differences [7].

Much of the "calm focus" reputation comes from L-theanine taken with caffeine. A meta-analysis of 11 placebo-controlled studies found moderate effect sizes favoring the combination for alertness and attention-switching accuracy in the first 2 hours, and trends suggested caffeine dose mattered more than L-theanine dose [6]. In the Lipton co-funded 2025 meta-analysis, the combination improved attention-switching accuracy in the second hour (SMD 0.33) [7]. The grade above therefore applies to L-theanine with caffeine, not on its own. Details are on the L-theanine monograph.

Bacopa monnieri has a long history in Ayurvedic medicine [11], and memory is where its trial evidence sits [9]. A systematic review of six randomized trials, all 12 weeks long, in adults without significant cognitive impairment found bacopa improved performance on 9 of 17 tests of memory free recall, with little evidence of enhancement in other domains [9]. The trials used 300-450 mg of extract per day [9]. In the 2026 network meta-analysis of healthy adults, low-dose bacopa outperformed placebo for delayed memory, although its authors note that the lack of direct comparisons may limit the strength of this evidence [10]. Single-dose use is a different question, covered on the bacopa monograph.

Creatine's memory evidence depends on age. A meta-analysis of 8 randomized trials in healthy people found an overall memory benefit (SMD = 0.29; 95% CI 0.04-0.53) with high heterogeneity, but the effect was concentrated in older adults aged 66-76 (SMD = 0.88) and absent in people aged 11-31 (SMD = 0.03) [12]. A preregistered crossover study, described by its authors as the largest on creatine and cognitive performance to date, tested 123 healthy adults, about half of them vegetarian, taking 5 g a day for 6 weeks and found an effect that bordered on significance for backward digit span (p = 0.064) and none on the exploratory tasks [13]. Side effects were reported more often with creatine than with placebo in that trial (RR = 4.25) [13]. See the creatine monograph.

For ginkgo, the memory result was d = -0.04 (95% CI -0.17 to 0.07) across 13 trials and 1,132 healthy participants [15]. More on this goal is on our memory hub.

Rhodiola rosea has been studied for physical and mental fatigue, and the evidence is mixed [17]. A 2012 systematic review found 11 controlled trials in healthy and clinical populations; three of five randomized trials of mental fatigue reported rhodiola effective, but every included study had either a high risk of bias or reporting flaws [17]. The reviewers concluded that research on rhodiola's efficacy is contradictory [17]. The rhodiola monograph covers the individual trials, and the energy hub compares other options.

Claims about calm rest on thinner evidence than claims about reaction time. In the 2026 L-theanine meta-analysis, the reduction in acute stress was modest (SMD = 0.31) and largely influenced by studies with a high risk of bias [5].

For sleep, a 2025 meta-analysis of 18 studies in people of all ages and health status found L-theanine improved subjective sleep onset latency (SMD = 0.15), daytime dysfunction (SMD = 0.33) and overall sleep quality score (SMD = 0.43) [8]. All three are self-reported measures, and the authors noted a lack of studies on pure L-theanine [8]. Other compounds for these goals are on the mood and stress and sleep hubs.

Not every perk is mental. In a meta-analysis of 23 studies in adults under 50 doing resistance training, creatine with training increased upper-body strength (WMD = 4.43 kg) and lower-body strength (WMD = 11.35 kg) compared with placebo [14]. Males showed significant strength gains, while females showed no significant gains [14]. One author has conducted industry-sponsored creatine research and serves on the scientific advisory boards of creatine manufacturers Alzchem and Create [14].

For endurance, a 2025 meta-analysis of 26 randomized trials in 668 healthy participants (mean age 22.0) found rhodiola improved VO2max (ES = 0.32), time to exhaustion (ES = 0.38) and time-trial performance, with heterogeneity that the authors said warrants cautious interpretation [18]. A 2026 meta-analysis of 9 randomized trials (424 healthy adults) across Rhodiola species found no significant effect on VO2max [23], so the direction of the evidence is inconsistent.

Expectation can change how people rate themselves without changing how they perform. In an experiment with healthy participants, tones described as affecting brain activity and cognition produced no change in measured reaction times or success rates on an attention task, but participants strongly believed it had improved their performance [19].

Telling people they are taking a placebo did not help either. In a randomized controlled trial of 78 healthy volunteers, 21 days of open-label placebo produced no benefit on any subjective or objective measure of cognitive performance [20]. Together these findings explain why this site grades placebo-controlled trials and reads self-ratings with care: expectation alone can make people believe they performed better when their measured performance did not change [19].

Some popular perks do not survive placebo-controlled testing in healthy people.

• Ginkgo for memory, focus and executive function. Effect sizes were non-significant and close to zero for memory, executive function (d = -0.05) and attention, and were not related to age, trial length or dose [15]. An updated review of 15 randomized trials in healthy people under 60 found no convincing evidence of a robust positive effect on any aspect of cognitive function, acute or longer term [16]. N, no benefit shown See the ginkgo monograph.
• Vitamins and minerals for maintaining cognitive function. A Cochrane review of 28 studies with more than 83,000 participants found that B vitamin supplements in cognitively healthy adults, mainly in their 60s and 70s, probably have little or no effect on global cognitive function at any time point up to 5 years [21]. The reviewers did not find evidence that any vitamin or mineral strategy for cognitively healthy adults in mid or late life had a meaningful effect, although the evidence does not permit definitive conclusions [21].
• Bacopa for speed of thinking. An earlier meta-analysis that pooled healthy and impaired participants found a shorter Trail B time with 12 weeks or more of bacopa [11], but the 2026 network meta-analysis restricted to healthy adults found no significant difference in processing speed [10]. C, limited

In the US, nootropics sold as dietary supplements reach shelves without FDA approval [24]. FDA states that under DSHEA it does not have the authority to approve dietary supplements before they are marketed [24]. When a label makes a structure/function claim, the firm must have substantiation that the claim is truthful and not misleading, but FDA generally does not approve dietary supplement claims or other labeling before use [24]. Status in the UK, Canada and Australia is covered on each compound's monograph.

Each badge is a grade for one compound and one outcome, based on human trials and updated when new studies are graded. A grade for caffeine and attention says nothing about caffeine and memory, and a null grade means good trials looked and found no effect, not that nobody has studied it.

Do nootropics actually work?

Some do, for specific outcomes, and the effects in healthy adults are mostly small. Caffeine improved attention and reaction time in a meta-analysis of 31 placebo-controlled trials [3], while ginkgo showed effects close to zero for memory, executive function and attention [15]. The grade for each compound and outcome is on its monograph.

What is the best-evidenced nootropic?

No single compound has the best evidence for every outcome. For attention, caffeine's evidence includes a meta-analysis of 31 randomized, double-blind trials with 1,455 participants [3], while its other outcomes and other compounds each carry their own grade.

How long do nootropics take to work?

It depends on the compound and how it was studied. Caffeine and L-theanine were tested as single doses, with effects measured within hours [3][5][6], while the bacopa trials that found memory effects ran for 12 weeks [9].

Can expecting a nootropic to work make you feel sharper?

In one experiment, participants who expected a cue to help them strongly believed it improved their performance, but their measured reaction times and success rates did not change [19]. This is why placebo-controlled trials, which compare the active compound with an identical-looking dummy, are the evidence this site grades.

Are nootropics approved by the FDA?

Nootropics sold as dietary supplements are not approved before sale. FDA states that under DSHEA it does not have the authority to approve dietary supplements before they are marketed [24].