Citicoline, also sold as CDP-choline, is one of the most popular "brain" supplements. Its marketing leans on a long research list: decades of use as a prescription drug in some countries, trials in stroke and brain injury, brain-imaging studies, and a branded form, Cognizin, tested in healthy adults.
That research list mixes two very different things. Most of it is hospital drug research in sick people, often with injections, at 1,000 to 2,000 mg a day. The supplement evidence, at 250 to 500 mg a day in healthy people, is a handful of small trials, most of them run with the company that sells Cognizin. This guide separates the two and walks through what each kind of trial actually found.
The short version
- Our verdict: possible small effects on some attention and memory tests, not established. The best trial in healthy older adults missed its main outcome, and the European Food Safety Authority did not accept a proposed citicoline memory claim in 2024, though Health Canada allows a modest attention claim.
- The biggest trials were drug trials, and they found no benefit. In 2,298 stroke patients and 1,213 brain-injury patients, citicoline did no better than placebo on the main outcomes. It is not a treatment for stroke, brain injury or dementia; stroke symptoms or a head injury need emergency care, and memory problems need a doctor.
- The main healthy-adult trials were run with the brand owner, and we found five completed industry trials, with about 470 registered participants, that we could not find published (a missing paper does not mean a trial failed).
- It is absorbed, but broken down first. The body splits it into choline and cytidine, which shows up in blood as uridine. The "over 90 percent bioavailable" claim traces to drug-maker reviews resting on a 1983 study of six people and on rat data.
- It is a poor choline source. Citicoline is about 20 percent choline, so 500 mg gives about 100 mg of choline, a fraction of the daily target.
- Usually well tolerated at 250 to 500 mg a day in trials of up to 12 weeks. It is not for children or pregnancy, and if you take Parkinson's, memory or ADHD medicines, ask your doctor first and do not change those medicines on your own.
What citicoline is
Citicoline (cytidine 5'-diphosphocholine) is a natural molecule the body makes on the way to phosphatidylcholine, a main building block of cell membranes. It is not itself a phospholipid. Chemically it carries two parts in equal amounts: choline and cytidine.
For decades it has been a prescription drug in some countries: in Japan an injectable form has been sold since 1967, and in Spain every registered citicoline product is prescription-only, starting with Ferrer's Somazina in 1975 for stroke and head-injury disorders. Canada and Australia allow it in over-the-counter health products for adults, with dose limits. A drug approval abroad does not show that a supplement works. In the US it is sold as a dietary supplement, both as generic citicoline and as Cognizin, the brand of Kyowa Hakko Bio, part of the Kirin group. In the European Union it is an authorized food ingredient limited to 500 mg a day in supplements, for adults only.
By weight, citicoline is about 20 to 21 percent choline and about half cytidine. So 250 mg supplies roughly 50 mg of choline and 500 mg roughly 100 mg, against a daily Adequate Intake of 425 mg for women and 550 mg for men.
What happens after you swallow it
Supplement pages often say citicoline is "over 90 percent bioavailable" and "crosses into the brain." The bioavailability figure traces to reviews by staff of Ferrer, the Spanish company that sells citicoline as a drug, citing a 1983 study in which six healthy people swallowed a single radioactively labeled 300 mg dose and less than 1 percent of the label turned up in their stool. That shows the label was absorbed. It does not show that intact citicoline reached the blood.
In people, an oral dose is broken down into its parts. In a crossover study of 12 adults, single doses raised blood choline for hours, and the cytidine part showed up as uridine, which rose by as much as 70 to 90 percent after 500 mg, while cytidine itself was not reliably detectable. So the body receives choline and uridine, which it can use to rebuild citicoline and membrane fats inside cells.
Brain-imaging studies are small and mixed. In one, a single dose raised a brain choline signal in younger adults but lowered it slightly in older adults. In another, six weeks of 500 mg a day in older adults raised markers of membrane turnover, but that change came during an open-label phase without a placebo comparison. A small study of Kyowa's Cognizin, without a placebo group, reported higher brain energy markers after six weeks. We found no human study showing that citicoline gets more choline into the brain than other choline sources.
The evidence at a glance
| The question | Best evidence | What it found | Our read |
|---|---|---|---|
| Memory and attention in healthy adults | Three small trials run with the Cognizin maker; one older university trial | Some attention and secondary memory scores improved; the largest trial missed its main outcome | Weak, not established |
| Older adults with memory complaints | Short double-blind trials (Cochrane 2005); longer studies mostly open-label or retrospective, at 1,000 mg a day | Some evidence for memory in short trials; a 2023 review rated its studies very low quality | Very weak; not a dementia treatment |
| Acute stroke (hospital drug use) | ICTUS, 2,298 patients; Cochrane review of 10 trials | No meaningful difference from placebo | Not a supplement question; seek emergency care |
| Brain injury (hospital drug use) | COBRIT, 1,213 patients | No difference from placebo at 90 days | Not a supplement question; seek emergency care |
| Glaucoma | Small trials of eye drops or an oral solution; the two largest were maker-funded | A 2023 review found insufficient evidence that it slows the disease | Research only; never instead of eye-pressure treatment |
| ADHD, addiction, sports | A few small trials | A child ADHD trial found no difference; addiction results mixed to negative; no sports trial of citicoline alone | No good evidence; do not change ADHD or Parkinson's medicines on your own |
Memory and focus in healthy adults
The best trial missed its main goal. The largest placebo-controlled trial in healthy people gave 100 adults aged 50 to 85 with everyday memory complaints 500 mg a day of Cognizin or placebo for 12 weeks. Its main outcome, a spatial memory test, did not differ from placebo. Two secondary memory scores did improve. Kyowa Hakko Bio sponsored the trial and helped design it, and three of its five authors worked for Kyowa companies.
Two smaller 28-day trials, also run with Kyowa co-authors, found fewer errors on an attention test in 60 healthy women aged 40 to 60, and better attention and motor speed in 75 adolescent boys. The women's study was published in a journal that PubMed does not index.
Other studies were mixed or weak. An older university trial of 1,000 mg a day for three months in 95 adults found a memory benefit only in a subgroup picked after the data were analyzed; a later 2,000 mg crossover in 32 of them improved recall. In a single-dose study of 24 healthy men, citicoline helped low performers and worsened scores in high performers. A two-week study of 40 students reported gains, but its own text describes it as both double-blind and single-blind and reports results mostly within groups. Drinks combining citicoline with caffeine cannot tell us what citicoline alone does.
Regulators disagree. In 2024, the European Food Safety Authority reviewed a proposed memory claim and concluded that a cause-and-effect relationship had not been established, noting one positive trial at 500 mg a day against a 1,000 mg study that did not confirm it. Health Canada's 2026 monograph, by contrast, allows an adult claim that citicoline helps improve sustained attention at 250 to 1,000 mg a day.
Several finished industry trials have no results we could find. On ClinicalTrials.gov we found five completed trials in healthy adults sponsored by Kyowa, Kirin or PepsiCo, with about 470 registered participants, finished between 2018 and 2025, that we could not find published. A missing paper does not prove a negative result, and the most recent finished in mid-2025, but the published record is smaller than the research that was done.
Older adults with memory problems
Most citicoline research in older adults is drug research in people with memory complaints linked to blood-vessel disease, mild cognitive impairment or dementia, usually at 1,000 mg a day. A 2005 Cochrane review of 14 mostly short trials found "some evidence" of benefit on memory and behavior and none on attention; the review discloses that its lead reviewer had been an investigator in some of the included trials. A large Italian study of 349 older adults with vascular changes on brain scans reported that scores on a cognitive screening test (the MMSE) held steady over nine months while untreated patients declined, but it was open-label and not randomized, and two of its three main outcomes did not differ. A Spanish trial in 347 stroke survivors reported better attention and executive scores at 1,000 mg a day for a year, but it had no placebo.
A 2023 meta-analysis reviewed seven studies, pooled six and found better scores, but only two of the seven were randomized trials, and the authors rated the evidence "very low." None of this shows that a supplement prevents or treats dementia. New memory problems need a medical evaluation.
Stroke and brain injury
This is hospital drug research, not supplement use. A 2002 analysis pooling four US oral trials, three of which had missed their own main outcomes, reported better recovery at three months, and it led to ICTUS, a large trial funded by Ferrer. ICTUS randomly assigned 2,298 people with moderate to severe stroke to placebo or citicoline, given by vein for three days and then by mouth at 2,000 mg a day, for six weeks in total. It was stopped early for futility: recovery at 90 days was essentially the same as placebo. A 2020 Cochrane review of 10 trials and 4,281 people found "little to no difference" in death, disability or recovery, on low-certainty evidence, and noted that drug companies sponsored six of the trials. A 2016 meta-analysis led by Ferrer staff reported a benefit.
In brain injury, COBRIT, funded by the US National Institutes of Health, randomly assigned 1,213 patients to 2,000 mg a day or placebo for 90 days and found no difference. A 2023 meta-analysis led by a Ferrer employee reported a benefit overall, but in its own breakdown by route, the two oral and tube-fed trials showed no effect and the benefit came from injected doses, though the authors judged the route difference not significant. Anyone with stroke symptoms or a head injury needs emergency care.
Glaucoma and other eye research
Citicoline eye drops and an oral solution have been studied in glaucoma, including the two largest trials, which Omikron, the Italian company that makes them, funded. A three-year trial of the eye drops in 80 people met one of its two main visual-field outcomes and missed the other, and its authors called it a pilot. A crossover trial of the oral solution in 155 people found better scores on a vision quality-of-life questionnaire. A 2023 systematic review of 10 studies found "a lack of sufficient evidence" that citicoline slows glaucoma. In children with lazy eye, early studies used injections, and the best oral study did not beat patching alone on its main outcome. These are medical products used under an eye doctor's care, never a replacement for glaucoma treatment.
ADHD, addiction, Parkinson's and sports
ADHD: a small randomized crossover trial in children found no difference from placebo, and one case report described a 7-year-old on ADHD medicine who developed agitation and suicidal behavior after citicoline and phosphatidylserine were added, which recurred when they were restarted; a single case cannot show cause, but do not add supplements to a child's ADHD treatment without the prescriber. Addiction: in a US government-funded trial of 130 people with bipolar disorder and cocaine dependence, cocaine use fell more than on placebo, most clearly in the first weeks, and trials in alcohol and methamphetamine use found no effect on drinking or drug use. Parkinson's: the largest recent trial reported modest motor benefits, but with injections, not pills, and two of its authors worked for the maker; do not adjust Parkinson's medicines on your own. Sports and gaming: we found no trial of citicoline alone on exercise performance, only multi-ingredient drinks with caffeine.
Dose, forms and cost
The Cognizin trials in healthy adults used 250 or 500 mg a day, for 28 days to 12 weeks; an older university trial at 1,000 mg a day found no overall benefit. Europe caps supplements at 500 mg a day. Higher doses, up to 2,000 mg a day, come mostly from drug trials in patients.
Cognizin is the brand used in the industry trials; generic citicoline is the same molecule. Labels list citicoline, not choline, except a few that print both. In our choline supplement ranking, citicoline costs about $0.22 to $0.37 a day at 250 to 300 mg, and over 30 times more per milligram of choline than the choline bitartrate powder in that ranking.
Safety
In trials of up to 12 weeks at 250 to 500 mg a day, serious side effects were not reported. In a 1983 five-day study at 600 to 1,000 mg a day, transient headaches occurred in up to 5 of 12 volunteers versus 1 on placebo, and digestive upset was the most common complaint in early drug surveillance. Large hospital trials at 2,000 mg a day found no safety differences from placebo, though a Cochrane review noted that harms were poorly reported.
In the largest healthy-adult trial, six mild, possibly related side effects occurred on citicoline versus two on placebo, and one person stopped because of a headache. Spanish drug labels warn that citicoline strengthens the effect of levodopa, a Parkinson's medicine, and should not be combined with meclofenoxate (centrophenoxine), and Australia requires a Parkinson's-medicine warning on citicoline products. We found no study measuring whether citicoline raises TMAO.
- Not a treatment. Citicoline does not treat stroke, brain injury, dementia, glaucoma or ADHD. Stroke symptoms or a head injury need emergency care, and new memory problems need a medical evaluation.
- Prescription medicines. If you take Parkinson's medicines such as levodopa, Alzheimer's drugs, ADHD stimulants or other prescription drugs, ask your doctor first, and do not change those medicines on your own.
- Children, pregnancy and breastfeeding. EU rules say citicoline supplements are not for children, and we found no safety data in pregnancy or breastfeeding.
Frequently asked questions
Does citicoline improve memory?
The evidence is weak. In the largest trial in healthy older adults, 500 mg a day of Cognizin for 12 weeks did not beat placebo on its main memory test, though two secondary scores improved. The three main healthy-adult trials of Cognizin were small and run with its maker, and the European Food Safety Authority did not accept a proposed citicoline memory claim in 2024. It is not a treatment for dementia, and new memory problems need a medical evaluation.
What is the difference between citicoline and CDP-choline?
They are the same molecule. Citicoline is the drug name for cytidine 5'-diphosphocholine, which supplements also call CDP-choline. Cognizin is one brand of it, made by Kyowa Hakko Bio.
How much citicoline should I take?
The Cognizin trials in healthy adults used 250 or 500 mg a day for 28 days to 12 weeks, and European rules cap supplements at 500 mg a day. Higher doses, up to 2,000 mg a day, come mostly from hospital drug trials in patients and are not a guide for supplement use.
Does citicoline help after a stroke or head injury?
Not in the largest trials. In 2,298 stroke patients and in 1,213 brain-injury patients, citicoline given as a hospital drug did no better than placebo on the main outcomes, and a Cochrane review of stroke trials found little to no difference. Stroke symptoms and head injuries need emergency medical care, not a supplement.
Is citicoline better than alpha-GPC?
We found no trial comparing their effects on memory or attention in healthy people. Alpha-GPC is about 40 percent choline by weight and citicoline about 20 percent, and citicoline also supplies cytidine, which the body turns into uridine. Both rest on small, mostly industry-funded trials.
Is citicoline a good source of choline?
No. It is only about 20 percent choline, so 500 mg supplies about 100 mg of choline, a fraction of the 425 to 550 mg daily target. Eggs or a choline bitartrate supplement supply choline far more cheaply.
Is citicoline safe?
At 250 to 500 mg a day in trials of up to 12 weeks, side effects were mostly mild, such as headaches or stomach upset, and serious ones were not reported. It is not for children, we found no safety data in pregnancy or breastfeeding, and people taking Parkinson's, memory or ADHD medicines should ask their doctor first and not change those medicines on their own.
Does citicoline help glaucoma?
A 2023 systematic review found insufficient evidence that it slows glaucoma. The studies were small, the two largest were funded by the maker of a citicoline eye drop and oral solution, and they used those medical products under an eye doctor's care. It is never a replacement for eye-pressure treatment.
The bottom line
Citicoline has a long drug history, but that history does not transfer to a supplement capsule. The large hospital trials in stroke and brain injury found no benefit, and the supplement evidence in healthy adults is a few small, mostly company-run trials, the best of which missed its main outcome. We could not find results for several finished industry trials, and European regulators did not accept a memory claim, though Health Canada allows a modest attention claim.
If you want to try it, 250 to 500 mg a day for several weeks matches the trials, Cognizin is the form used in the recent healthy-adult trials, and modest expectations are warranted. If you mainly want more choline, a choline salt or eggs are far cheaper. Stroke symptoms or a head injury need emergency care, and memory loss or a diagnosed condition needs a doctor, not a supplement. If you take Parkinson's, memory or ADHD medicines, ask your doctor before adding citicoline and do not change those medicines on your own.