What are nootropics? A plain-English guide to what works

A nootropic is a substance whose action is described as improving human thinking, learning and memory, especially where these functions are impaired [1]. A 2022 review notes that nootropics are also known as "smart drugs" and calls them a diverse group of medicinal substances [1].

The word was coined by the researcher C Giurgea, whose work in the late 1960s produced the first drug of a class called the pyrrolidones, and he used it to mean enhancement of learning and memory [2].

The same 2022 review sorts nootropics into four subgroups: classical nootropic compounds, substances that increase brain metabolism, cholinergic substances, and plants and their extracts [1].

This guide covers supplements sold over the counter. It does not cover prescription smart drugs, which a 2025 review describes as drugs that typically healthy users take to improve mental performance [3]. That review found relevant uncertainty about whether smart drugs improve executive functions, and it describes clinical concerns about non-prescribed use of stimulant smart drugs by otherwise healthy people [3].

NCCIH reports that in the 2012 National Health Interview Survey, 89 percent of US adults who took supplements other than vitamins and minerals gave wellness reasons, and 22 percent of them named improving memory or concentration [19].

Many products sold as nootropics are blends. A 2023 review of 50 supplements marketed as "cognitive enhancement", "brain health", "brain boosters" or "nootropics" notes that such products have often appeared as multicomponent formulations [14]. Three of that review's six authors are affiliated with Banned Substances Control Group, a supplement-testing company [14].

If you have a specific aim in mind, our goal pages collect the graded evidence for each one: focus, memory, energy, mood and stress, sleep, physical performance and work and study.

In the US, UK and Canada, products sold as supplements fall under supplement, food or natural health product rules rather than the rules for prescription medicines [16][17][18]. Some products marketed as nootropics have been found to contain unapproved or unauthorized ingredients [13][14]. A 2023 review found significant global variability in what qualifies as a legal nootropic [14].

Table: How supplements sold as nootropics are regulated, by market (checked November 11, 2026)

In Canada, natural health products are regulated under their own framework, separate from prescription drugs [18]. In the UK, guidance from the Food Standards Agency says food supplements are intended to supplement the normal diet [17].

Under US law, a firm is responsible for ensuring that the supplements it makes or distributes are not adulterated or misbranded [16]. FDA enforces these rules after products reach the market, through inspections and monitoring of the marketplace [16]. A product being on sale therefore does not mean FDA approved it before it reached the market [16]. In the US, FDA advises talking to a doctor, pharmacist or other health care professional before deciding to use a dietary supplement [16].

The fairest test compares a substance with a placebo, a dummy pill that looks the same, in a randomized controlled trial. People are assigned by chance, and in double-blind trials neither they nor the researchers know who got what. A meta-analysis pools the results of many such trials.

For example, the caffeine meta-analysis described below included only randomized, double-blind, placebo-controlled trials of pure caffeine in rested healthy adults [6]. That design is why its result carries weight.

We grade each compound separately for each outcome, because a substance can help one thing and do nothing for another. Population matters too: results in older adults, athletes or people with a health condition may not apply to healthy younger adults. Our guide on how to read a supplement study explains these terms in more depth.

Two factors that are not supplements also show up on cognitive tests: sleep loss and exercise.

A meta-analysis of 70 articles covering 147 cognitive tests looked at adults after less than 48 hours of total sleep loss [4]. It covered six areas: simple attention, complex attention, working memory, processing speed, short-term memory and reasoning [4]. Effects ranged from small and not significant for reasoning accuracy to large for lapses in simple attention [4].

Exercise also shows up on cognitive tests. A 2025 meta-review pooled 30 meta-analyses covering 383 studies and 18,347 participants, from children to older adults [5]. A single bout of exercise improved cognitive function with a small-to-medium effect (mean SMD 0.33) [5]. Neither participants' age and cognitive status nor exercise intensity, type and duration changed that effect [5].

Neither finding is about a supplement, and neither costs anything.

A 2025 meta-analysis pooled 31 randomized, double-blind, placebo-controlled trials with 1,455 rested healthy adults [6]. Caffeine improved both accuracy (g = 0.27) and reaction time (g = 0.28) on attention tests [6].

In these trials, doses of 200 mg or more improved reaction time and accuracy more than lower doses [6]. Accuracy improved only up to a certain point before declining [6]. The effect was not related to how much caffeine people usually drank, how complex the task was, or which kind of attention the test measured [6]. These were single doses, so the trials say little about long-term daily use. Our caffeine page also discusses whether, in regular users, part of the benefit reflects relief from caffeine withdrawal.

One well-studied caution is sleep. In a meta-analysis of 24 studies, caffeine reduced total sleep time by 45 minutes [7]. For most adults, FDA has cited 400 mg a day as an amount not generally associated with negative effects [20].

Read the full evidence on caffeine.

A 2025 meta-analysis pooled 69 randomized controlled trials with 1,937 adults, with or without exercise training [8]. Creatine plus resistance training produced small but statistically significant gains in bench and chest press strength and squat strength compared with placebo [8]. One of its authors is a scientific advisor for Bear Balanced, a company that makes creatine products [8].

Not every measure improved. There was no overall improvement in handgrip or leg press strength, and benefits were most consistent in younger adults and men [8].

For memory, evidence is mixed. A meta-analysis of 8 placebo-controlled trials in healthy people found that creatine improved memory measures overall [9]. The effect was significant in older adults aged 66-76 but not in people aged 11-31 [9]. Trials used doses of about 2.2-20 g a day for 5 days to 24 weeks [9].

Concern about creatine and the kidneys persists, largely because creatine intake is associated with higher levels of a blood marker called serum creatinine [15]. A 2025 review of 21 studies, 12 of them pooled with 177 people taking creatine and 263 controls, looked at this question [15]. It found a small rise in serum creatinine, significant in studies lasting a week or less and in those lasting more than 12 weeks but not in those lasting 1 to 12 weeks [15]. There was no significant change in a measure of kidney filtration (GFR) [15].

Read the full evidence, including safety, on creatine.

A 2014 review of 11 randomized placebo-controlled studies tested tea compounds, alone or with caffeine, in healthy adults, and pooled an outcome when at least 3 studies had data [10]. Compared with placebo, caffeine with L-theanine had moderate effects on self-rated alertness and attention-switching accuracy in the first 2 hours after a dose [10].

The same review found trends toward larger changes in effect size with the caffeine dose than with the L-theanine dose [10]. So the benefit cannot be credited to L-theanine alone, and the grade covers the combination only. The grade also carries an industry-funded label: the trials behind it are small, and most were run or funded by tea companies, as the L-theanine page details.

Read the full evidence, including safety, on L-theanine.

A 2012 systematic review found 6 randomized controlled trials, all lasting 12 weeks, in adults without significant cognitive impairment [11]. The trials used 300-450 mg of extract a day [11].

Across those trials, bacopa improved performance on 9 of 17 tests of free recall, which means remembering a list without prompts [11]. There was little evidence of benefit in any other cognitive area [11]. The grade also draws on later trials of delayed recall, two of which found no difference; the bacopa page covers them.

Read the full evidence, including safety, on bacopa.

For ginkgo biloba, a meta-analysis of randomized controlled trials in healthy people found effect sizes close to zero for memory (d = -0.04) [12].

It pooled trials with data on memory (13 trials), executive function (7 trials) and attention (8 trials) [12]. The authors reported no ascertainable positive effects on memory, executive function or attention in healthy individuals [12]. The effects were not related to age, trial length or dose [12]. Read the full evidence, including safety, on ginkgo.

We grade single ingredients, not multi-ingredient "brain" blends. The 2023 review of 50 nootropic supplements focused on unauthorized ingredients in such products [14].

Prescription smart drugs used without a prescription are outside the scope of this guide. A 2025 review found relevant uncertainty about their effect on executive functions [3].

For more on which claimed benefits hold up, see our guide do nootropics work.

Safety depends on the substance, the dose, the product and the person. NCCIH notes that many supplements come from natural sources, but "natural" does not always mean "safe" [19].

Interactions are possible. FDA says some supplements might interact with medicines or other supplements [16]. NCCIH adds that supplements may pose risks for people with certain medical problems or who are going to have surgery [19].

Product quality is another. In a 2021 study, researchers bought online 10 cognitive-enhancement supplements whose labels listed drugs not approved for human use in the US, and tested them [13]. They found unapproved drugs, several detected drugs were not on the label, and 9 of 12 declared quantities were inaccurate [13]. Using a single product at its labeled serving, a consumer could be exposed to as many as 4 unapproved drugs, at up to four times a pharmaceutical dose [13]. The authors concluded that the health effects of such untested combinations are unknown [13]. NCCIH also notes that the word "standardized" on a label does not necessarily guarantee quality or consistency [19].

If you take any medicines, talk to your doctor or pharmacist before combining them with a supplement. Our guide are nootropics safe covers this in more detail.

Each grade badge on this page applies to one compound and one outcome, so caffeine's grade for attention says nothing about caffeine and sleep. The evidence matrix shows every graded pair, and how we grade evidence explains the rubric.

What is the difference between nootropics and smart drugs?

A 2022 review uses the two terms for the same broad group of substances [1]. A 2025 review describes the typical smart-drug user as a typically healthy person who takes drugs to improve mental performance [3]. This guide covers supplements sold over the counter.

Do nootropics actually work?

It depends on the substance and the outcome. Caffeine improved attention test scores in a meta-analysis of 31 placebo-controlled trials [6], while a meta-analysis of ginkgo trials in healthy people found no ascertainable positive effects [12]. Each compound page shows a separate grade for each outcome.

Are nootropics legal?

Rules differ by country, and a 2023 review found wide variation in what qualifies as a legal nootropic [14]. In the US, FDA does not approve dietary supplements before they are marketed [16]; in the UK food supplements are regulated as food [17]; in Canada natural health products need a product license [18].

Are nootropics safe?

NCCIH notes that natural does not always mean safe and that supplements may interact with medicines [19]. In a test of 10 cognitive-enhancement supplements chosen because their labels listed drugs not approved in the US, researchers found unapproved drugs, and 9 of 12 declared quantities were inaccurate [13]. Talk to a doctor or pharmacist before combining any supplement with medicines.