Semax with selank and dihexa dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Semax with selank and dihexa is three brain peptides sold as one focus stack. Two are approved medicines in Russia, with small studies done there. The third rests on a paper that was pulled by its journal in 2025, after a warning notice in 2021. Nobody has tested the mix, and no vial size is standard across sellers.
Evidence grade for Semax with selank and dihexa: Limited. The rule: people have taken it in a published study, but fewer than 100 of them. The sum on this page: 1 completed trial, 62 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 62
- Human studies
- 1
- Found nothing
- 0
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
1 completed trial, 62 people given it
7 effects reported, 5 unwanted, 2 wanted, by people using it, not a trial
Goal pages: Brain, memory and mood, Sleep
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Three brain peptides sold as one stack. One is meant to sharpen you up, one to calm you down, one to build connections. Two of the three are registered medicines in Russia. The third rests on a paper that got retracted in 2025.
What people take it for
- Focus and mental sharpness.
- Less anxiety without feeling dopey.
- Memory and learning.
- Recovery after a brain injury.
What studies in people showed
Nobody has tested the three together. Selank has the best record. Sixty two people with bad anxiety and burnout got selank or a standard anxiety drug. The anxiety relief was about the same in both. Selank also picked people up, which the paper calls a psychostimulant effect. Semax is registered and used in Russia, and the study on this page is in rats. One dose raised a brain growth protein 1.4 times in the rat hippocampus and the rats learned an avoidance task better. Both Russian records are domestic and nobody outside Russia has repeated them. Now dihexa. The paper that explained how it works got an expression of concern in 2021 and was retracted by the journal in 2025. Some of its authors worked for a company developing the drug. A retracted paper is not proof the drug does nothing. It does mean the main published reason for putting dihexa in a brain stack has been pulled.
What people report
Reports, not study results
The good
- Sharper focus and easier speech within the first hour, credited to the semax.
- Less anxiety without feeling flat, credited to the selank. That matches what the trial found.
The bad
- Irritability or feeling overstimulated, especially at higher amounts.
- Headache.
- Most people say they notice nothing from the dihexa part.
- One part is meant to speed you up and one to slow you down, and the seller picked the balance for you.
- Semax and selank are used as nose drops in Russia. Stacks sold to inject change the route the human use came from.
Where these come from: Nootropic and peptide forums plus seller pages. People talking, about their own thinking, which is the easiest thing in the world to fool.
My bottom line
When the paper that explains how a drug works gets retracted, treat the drug as unknown, not promising. Two thirds of this stack has something behind it. One third does not any more.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Semax with selank and dihexa has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Mood and anxiety62 people · 1 study
What people using it report
Real people telling you what happened to them. Nobody checked it, and the people who post are not a fair sample, so it cannot prove anything works. It is still the best guide on this page to what people actually do with Semax with selank and dihexa, what they expect, and what goes wrong. The full account, including the negative reports, is below.
34 of the 36 indexed goals have no study of any kind behind Semax with selank and dihexa
No study in people, animals or cells on this page reports a result for these. That does not prove Semax with selank and dihexa does nothing for them. It does mean anything you have heard about Semax with selank and dihexa and one of these did not come from a study cited here.
Show full evidence
What is Semax with selank and dihexa?
Semax with selank and dihexa is three brain peptides sold as one focus stack. Two are approved medicines in Russia, with small studies done there. The third rests on a paper that was pulled by its journal in 2025, after a warning notice in 2021. Nobody has tested the mix, and no vial size is standard across sellers.
The pitch is one peptide to wake you up, one to calm you down, and one to grow new brain connections. That covers focus, anxiety and long-term learning. Each third of that pitch has a different evidence problem.
Semax is a small peptide copied from a piece of the stress hormone ACTH. It is approved and used by doctors in Russia. Its lab work is mostly in rats. In rats, one dose of 50 micrograms per kilogram raised a brain growth protein called BDNF in the memory centre of the brain, by up to 1.4 times. It raised activity of that protein's receptor by 1.6 times. The genes for the two rose three times and two times. The treated rats also learned to avoid a warning signal more often. That is rats, one dose, and brain tissue.
Selank is a copy of a small immune peptide called tuftsin. It is also approved in Russia. It has a proper comparison study. 62 patients with long-running anxiety or nervous exhaustion were treated: 30 with selank and 32 with medazepam, an older anti-anxiety drug. They were rated on standard anxiety scales. The two drugs calmed anxiety about the same. Selank also lifted energy and alertness. That is a real study in people, in a Russian journal. It compared selank with another drug, not with a dummy.
Dihexa is the problem. The paper that set out how it works said it binds a growth factor called HGF and switches on its receptor, and that it grows new connections in the memory centre of the brain. The journal put a warning notice on it in 2021 and pulled it in 2025. Some of the authors worked for a company making the compound, and the paper said so. A pulled paper does not prove the compound is useless. But it means the main published reason to put dihexa in a focus stack has been withdrawn by the journal.
No vial size or capsule strength is standard across sellers for this trio. So this page does not give a per-dose amount. Whatever the split, one ingredient is sold to wake you up and one to calm you down. The blend puts opposite goals in one draw, at a mix the buyer did not pick. And the third ingredient rests on withdrawn evidence.
How does Semax with selank and dihexa work?
In rats, semax seems to raise the brain growth protein BDNF and its receptor in the memory centre of the brain. Russian medical papers describe it as protecting nerve cells. Selank is a copy of the immune peptide tuftsin. It calms anxiety, and this is linked to how the body breaks down its own natural painkillers. Dihexa was described as a peptide made from a blood pressure hormone piece, working through the growth factor HGF and its receptor. The paper that said so has since been pulled. No published work looks at the three together.
What have studies in people found about Semax with selank and dihexa?
One ingredient has a small study in people against another drug. One has rat lab work and a history of use in Russia. One has a lab paper that was pulled. The stack has nothing.
- Selank: 62 patients with long-running anxiety or nervous exhaustion. It calmed anxiety about as well as medazepam, and also lifted energy and alertness.
- Semax: approved and used by doctors in Russia. The lab work listed here is in rats.
- Dihexa: no study in people. The key paper on how it works was pulled in 2025, after a warning notice in 2021.
- The stack: no published study and no listed trial.
What this does not tell you: The medical papers for the two Russian peptides are from inside Russia, mostly in Russian. No independent team outside Russia has repeated them. That lowers how sure we can be. It is not a reason to throw the work out. It is the honest description of where this evidence sits.
What do people who took Semax with selank and dihexa report?
This is what real people say happened to them, good and bad. Nobody measured it. A report cannot tell a real effect from the lift people get just from expecting it to work, from a diet or training change made at the same time, or from what was really in the vial. We still put it near the top. It is the next best thing to a study in people: what happens when real people use it, including what goes wrong.
- Sharper focus and finding words more easily within the first hour, which people credit to the semax.
- Less anxiety without feeling sleepy, which people credit to the selank. That matches what the comparison study found.
- Irritability or feeling overstimulated, mostly at higher amounts.
- Headache.
- No effect people could notice from the dihexa. This is the most common specific complaint about these stacks.
- Trouble telling the three apart, since they are taken together.
Sources: Nootropic forums including r/nootropics and r/peptides, and vendor pages. Uncontrolled self-reports in a domain where expectation effects on subjective cognition are large and where nobody is measuring anything.
The state of the research
The pulled paper is the fact that should change a decision. The paper that set out how a compound works was withdrawn by its journal, after a warning notice that stood for four years. The sensible response is to treat the compound as unknown, not as promising. Dihexa is still sold and stacked on the strength of research that now has a hole in the middle.
The second issue is the shape of the product. Selling a wake-up peptide and a calming peptide at a fixed mix means the seller has decided the balance between the two for every buyer. You cannot adjust it. And you cannot find out which ingredient caused whatever happens.
The third issue is how it goes in. In Russia, semax and selank are used as nose drops. Stacks sold as shots take two peptides out of the way they were used in medicine.
The evidence, in charts
Fig. 1a · how many people
62people, across 1 study in people cited here
| Study | People | Share |
|---|---|---|
| Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 2008 | 62 | 100% |
The whole total is one study of 62. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
1 of 3 sources here is a study in people. The rest are not.
- Study in people · done in people133%
- Animal study · done in animals267%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 3 different years, 2006 to 2014, counted from the list of sources on this page. The newest source on file is from 2014, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Blend
- Molecule weight
- Not on file
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
Half-life as stated on file: Not defined for the stack, and no pharmacokinetic study of the combination exists. The two Russian peptides are typically dosed intranasally rather than injected.
No amino acid sequence is on file for Semax with selank and dihexa, which is expected: a blend is not built from amino acids.
Fig. 6 · what is in the vial
We cannot show how much of each is in this blend
Sellers do not agree on a vial size for Semax with selank and dihexa, so nobody outside can know how much of each ingredient is in it. Splitting the bar evenly would make up the very number this page is here to question.
- SemaxModerate. At least one finished study in people, and at least 100 people who took it. 4 completed trials, 354 people given it.amount not stated
- SelankModerate. At least one finished study in people, and at least 100 people who took it. 3 completed trials, 192 people given it.amount not stated
- DihexaAnimal or lab only. Only animal or lab studies on this page. No study in people yet. 1 animal study, no human study.amount not stated
Ingredient list from the product labels we have. Amounts are what the label says is in the vial, never a dose.
The studies we cite
- Study in people2008[Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia]
Selank calmed anxiety about as well as an older anti-anxiety drug, in a small Russian study. 62 patients with long-running anxiety or nervous exhaustion were treated, 30 with selank and 32 with medazepam. They were rated on standard anxiety scales. The two drugs came out about the same, and selank also lifted energy and alertness. Two limits matter. There was no dummy group, so nothing tells us how these patients would have done untreated. And no team outside Russia has repeated it.
62 patients with generalised anxiety disorder and neurasthenia, 30 on selank and 32 on medazepam, assessed with the Hamilton, Zung and CGI scales alongside serum enkephalin activity. The anxiolytic effects of the two drugs were similar, and selank also showed antiasthenic and psychostimulant effects. An active comparator trial in a Russian journal, with no Western replication.
- Animal study2006Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus
In rats, one dose of semax raised a brain growth protein in the memory centre of the brain. The protein, called BDNF, went up by as much as 1.4 times. Activity of its receptor went up 1.6 times, and the genes for both rose too. The treated rats also learned to avoid a warning signal more often. This was rats and a single dose. It says nothing about people.
A single application of semax at 50 micrograms per kilogram produced a maximal 1.4-fold increase in BDNF protein and a 1.6-fold increase in trkB tyrosine phosphorylation, with three-fold and two-fold increases in exon III BDNF and trkB mRNA, in rat hippocampus. Treated animals showed a distinct increase in conditioned avoidance reactions. Rats, single dose.
- Animal study2014
Pulled or flagged by the journalRetracted. PubMed types this record as a Retracted Publication.
The procognitive and synaptogenic effects of angiotensin IV-derived peptides are dependent on activation of the hepatocyte growth factor/c-met systemThis is the paper that set out how dihexa is supposed to work, and it has been pulled. It said dihexa binds a growth factor called HGF and grows new brain connections in animals. The journal put a warning notice on it in 2021 and pulled it in 2025. Several authors worked for a company making the compound, and the paper said so. It is listed here because being pulled is the key fact about dihexa, not because it supports it.
The paper establishing dihexa's claimed mechanism, reporting that it binds hepatocyte growth factor, induces c-Met phosphorylation and produces hippocampal spinogenesis and synaptogenesis. PubMed flags it as a retracted publication: an expression of concern was published in 2021 and the retraction followed in 2025. Several authors were affiliated with a company developing the compound, disclosed in the paper. It is cited here because its withdrawal is the relevant fact about dihexa, not because it supports the compound.
Where to buy Semax with selank and dihexa
No seller we track lists Semax with selank and dihexa yet. We read sellers’ public product lists every week, and this section fills in as soon as one does. Every seller, graded
Common questions
Has Semax with selank and dihexa been tested in people?
Yes. 62 people given it across 1 completed trial cited here, 0 of which found nothing. Semax with selank and dihexa is three brain peptides sold as one focus stack. Two are approved medicines in Russia, with small studies done there. The third rests on a paper that was pulled by its journal in 2025, after a warning notice in 2021. Nobody has tested the mix, and no vial size is standard across sellers.
What is the Semax with selank and dihexa dosage?
No human dose established. Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose. 1 completed trial, 62 people given it
Is Semax with selank and dihexa FDA-approved?
None of the three is approved in the United States. Semax and selank are registered medicines in Russia. Dihexa has never been approved anywhere, and never finished human testing.
Was a paper on one of these retracted?
Yes. The paper that set out how dihexa works through the growth factor HGF got a warning notice in 2021. The journal pulled it in 2025. That paper is the main published reason for putting dihexa in a focus stack.
Does selank have a real trial?
It has a comparison study in 62 patients with long-running anxiety or nervous exhaustion. It calmed anxiety about as well as the older drug medazepam. It is a study from inside Russia, and no team outside Russia has repeated it.
What is the semax evidence?
Approval as a medicine in Russia, plus lab work in rats. The study listed here gave rats 50 micrograms per kilogram and measured a brain growth protein called BDNF, and its receptor, in the memory centre of the brain. BDNF went up 1.4 times.
Is combining a stimulating and a calming peptide sensible?
It is at least a choice, and the seller made it. A fixed mix means you cannot raise one and lower the other. And you cannot tell which of the three is causing any effect you notice.
Should these be injected?
Semax and selank are used as nose drops in the medical practice their evidence comes from. A stack sold as a shot moves away from the way they were used in people.