No trial has tested Selank against a placebo, so nothing can tell you.
Selank has more anxiety-specific human research than almost any peptide sold this way. Three Russian trials, 192 patients between them, all published. And not one of them included a placebo arm.
Every trial compared Selank against a benzodiazepine or added it to one.123 That design can tell you whether two drugs look similar. It cannot tell you whether either one beat doing nothing, and it cannot establish a rate for an effect going the wrong way.
Worsened anxiety is not reported in the published abstracts of any of the three. That is not the same as it being ruled out, for reasons below.
The route does not match either. All three trials gave Selank as nasal drops. In our capture, 142 of 159 Selank listings are vials.4
What did the human trials actually test?
Three studies came out of one country and largely one research group, with a benzodiazepine in every design.
| Study | People | Design | Reported result |
|---|---|---|---|
| Zozulia et al., 2008 | 62 with generalised anxiety disorder or neurasthenia | Selank in 30 against medazepam in 32 | Anxiolytic effects similar; Selank also antiasthenic and psychostimulant1 |
| Medvedev et al., 2014 | 60 with phobic-anxiety and somatoform disorders | Selank against phenazepam | Pronounced anxiolytic and mild nootropic effect; no objectionable side effects, unlike phenazepam2 |
| Medvedev et al., 2015 | 70 with anxiety disorders | Phenazepam alone in 30, phenazepam plus Selank in 40 | Combination reduced phenazepam's side effects3 |
The missing arm is the whole problem. A trial comparing two active drugs and finding them similar is consistent with both working and with neither working. Anxiety scales respond substantially to placebo, and without a placebo group there is no way to separate the drug from that response.
This is not a criticism of the researchers, who were comparing against standard care in their setting. It is a limit on what the studies can answer, and the question being asked here is one of the things they cannot.
Three further limits. All three come from the same country and largely the same group, none has been replicated in the United States or Europe, and the comparators, medazepam and phenazepam, are not approved medicines in the US.
Was worsening recorded?
Not in the published abstracts. That is a narrower statement than it sounds.
The 2014 abstract states that Selank did not exert objectionable side effects, in contrast to phenazepam. The 2008 abstract reports similar anxiolytic effects to medazepam with additional effects. Neither describes anxiety worsening.
Four reasons that does not settle it.
The full texts are in Russian and we have read the English abstracts. An adverse event table in the body of a paper can say things an abstract does not.
An abstract reporting no objectionable side effects is a summary judgement, not an adverse event count.
The trials were in diagnosed patients receiving a course of treatment under supervision. People posting about a bad reaction are usually not in that situation.
With no placebo arm, even a recorded worsening could not have been attributed to the drug instead of to the disorder being treated.
What do people actually report?
Five separate outcomes. Averaging them would hide the thing that makes them useful, because they go in different directions.
- Relief. Reduced anxiety, a calmer baseline. This is what the trials report and what most accounts describe.
- Acute anxiety or panic. Anxiety rising instead of falling, in some cases sharply.
- Low mood. Feeling flat or down during or after use. That is a different report from anxiety.
- Emotional flattening. Reduced anxiety along with reduced everything else. People describing it are usually clear that it is not the same as low mood.
- No effect. Nothing noticeable in either direction.
Nothing in the research explains why one person would get one of these and another a different one. We are not going to offer a reason, because no source supports one.
What can be said is that the trials measured group averages on anxiety scales. A group average improving is compatible with some individuals getting worse, and the published abstracts do not report the distribution.
For the broader family, see the nootropic peptides, sorted out.
How is it supposed to work?
Nobody knows. Every proposed route comes from animals or cells.
Selank is a synthetic analogue of tuftsin, a naturally occurring immune peptide, with an added sequence intended to slow its breakdown. It comes from the same Russian research programme as Semax. Semax is sold alongside it and has a different proposed mechanism, and our Semax versus Selank comparison sets out what separates them.
- The enkephalin route. The 2008 trial measured serum enkephalin activity alongside its clinical outcomes, reporting that the blood half-life of leu-enkephalin was shortened at the start of treatment and lengthened during it.1 Enkephalins are the body's own opioid-like signalling peptides. Whether that change causes the clinical effect, accompanies it, or is incidental is not established.
- GABA and serotonin. Animal work describes effects on GABA-A receptor expression and on monoamine systems. That is the usual proposed route for an anxiolytic.
- Gene expression. Laboratory studies describe changes in expression of several genes involved in neurotransmission.
None of this has been demonstrated as the mechanism in a person, and none of it predicts who will respond or how.
Does injected Selank have the same evidence?
All three trials used nasal drops. Most of what is sold is a vial.
Selank appears in 159 listings across 102 sellers in our capture. 142 of those are vials, against 15 nasal sprays or spray-worded products.4 So the dominant format is the one with no trial behind it.
What is known for the nasal route: three trials, 192 patients, and the limits above.
What is known for injection: we could not find a human trial of injected Selank for anxiety, by any route, in any language we could search.
A peptide given nasally and a peptide given under the skin are not interchangeable: different absorption, different peak, different distribution.
Has this been documented for any anxiety drug?
For benzodiazepines, yes, and the range of reported rates is the interesting part.
Benzodiazepines have a documented disinhibitory or paradoxical reaction, in which the drug produces something close to the opposite of its intended effect. A 2002 review in the Psychiatric Bulletin lists the behaviours as "increased anxiety, vivid dreams, hyperactivity, sexual disinhibition, hostility and rage".5 A 2004 review in Pharmacotherapy describes paradoxical reactions as "relatively uncommon", occurring in "less than 1% of patients".6
Then the rates stop agreeing with each other.
| Study, as reported in the 2002 review5 | Rate on the drug | Rate on placebo |
|---|---|---|
| Greenblatt et al., 1984, across 45 controlled trials | No difference in behavioural disinhibition | No difference |
| Dietch and Jennings, 1988, aggressive dyscontrol | Less than 1% | "similar to the incidence with placebo" |
| O'Sullivan et al., 1994, alprazolam | 13.7% had paradoxical reactions | None |
| Gardner and Cowdrey, 1985, alprazolam in borderline personality disorder | 58% | 8% |
Those are not small disagreements. Depending on the drug, the population and the study, the same phenomenon is reported as indistinguishable from placebo or as happening to more than half the people given it. The 2002 review puts the overall incidence as "small" and adds the reason the numbers scatter: "because overt rage reactions are rare, they are difficult to quantify."5
Two things follow, and the second one cuts against the argument made here.
The first is that a drug class prescribed for anxiety is known to worsen it in some people. That is established for benzodiazepines, the comparator in all three Selank trials. It says nothing about Selank. Selank has a different proposed mechanism and has never been examined for this.
The second is that placebo control was not sufficient on its own. Every row in that table is a controlled comparison, and they still produce answers from zero to 58%. So the complaint made above is narrower than "a placebo arm would have told us". A placebo arm would have made the question answerable. Answering it would then have taken the kind of replication across populations that the benzodiazepine literature took decades to accumulate and still has not settled.
The 2002 review also identifies who is at higher risk on benzodiazepines: people with impulse control problems, neurological disorders or learning disabilities, and people under 18 or over 65.5 Those are risk factors for one drug class, established in that class's own literature. Nobody has looked for an equivalent list for Selank.
Who was actually in those trials?
Three different populations, and none of them was simply people with anxiety who bought a peptide.
The 2008 trial recruited patients with generalised anxiety disorder and neurasthenia.1 Neurasthenia is a diagnosis of fatigue, weakness and irritability that remains in the ICD but was dropped from the American diagnostic manual decades ago and is not in routine Western use.
So part of the population in the Selank trial was defined by a category that a US or UK clinician would not assign. That does not make the finding wrong. It does mean a reader cannot straightforwardly place themselves in that trial population.
The 2014 trial recruited phobic-anxiety and somatoform disorders, a different group again, and the 2015 trial recruited people already on a benzodiazepine.23 Three trials, three populations, none of them simply people with anxiety who bought a peptide.
When should you see someone about this?
Some of what appears in these accounts is not a side effect question.
A panic attack that does not settle, or panic attacks that start happening when they did not before.
Anxiety that is stopping you working, sleeping or leaving the house.
Low mood that persists for more than a couple of weeks, loss of interest in things you normally care about, or any thought of harming yourself.
Anxiety alongside a racing heart, chest pain or breathlessness. That needs ruling out as something physical rather than assumed to be psychological.
If you are in crisis, contact your local emergency number or a crisis line now rather than waiting for an appointment. In the US that is 988. In the UK, Samaritans on 116 123. These lines are free and answer at any hour.
Stopping a compound you bought is a reasonable thing to do while you work out what is happening, and nothing in the Selank trials describes a withdrawal effect. That applies to Selank and not to a prescribed medicine. Benzodiazepines and antidepressants both need a clinician's plan to come off, and the 2015 trial enrolled people who were already taking one.
Our guide to telling your doctor about peptides covers that conversation.
Common questions
Can Selank make anxiety worse?
No trial can answer this, because no trial of Selank for anxiety included a placebo arm. All three compared it against a benzodiazepine or added it to one. Worsening is not described in the published abstracts. That is not the same as having been ruled out.
Is there good evidence that Selank works for anxiety?
There are three Russian trials in 192 patients, more anxiety-specific human research than most peptides have. None had a placebo group, none has been replicated outside Russia, and the comparator drugs are not approved in the US.
Why does a placebo arm matter so much here?
Because anxiety scales respond substantially to placebo. A trial finding two active drugs similar is consistent with both working and with neither working, and without a placebo group there is no way to tell those apart.
Has injected Selank been studied?
Not for anxiety, as far as we could find. All three trials used nasal drops. In our capture, 142 of 159 Selank listings are vials, so the format most people buy is the one without trial evidence.
Do anxiety drugs ever make anxiety worse?
For benzodiazepines, yes. A disinhibitory reaction that includes increased anxiety is documented, and the reported rates range from no different to placebo up to 13.7% against none on placebo in one alprazolam trial, depending on the drug, the population and the study. Those are the drugs Selank was compared against. Nobody has looked for the equivalent with Selank.
Why do people report such different effects?
Nothing in the research explains it, and we are not going to guess. What can be said is that the trials reported group averages, and a group average improving is compatible with some people getting worse.
Is Selank the same as Semax?
No. Both came out of the same Russian research programme and both are sold as nasal sprays and vials, but they are different peptides with different proposed mechanisms and different claimed effects. Our Semax versus Selank comparison covers what each has been tested for.
How often does an anxiety drug cause the opposite effect?
For benzodiazepines, the reported rates do not agree. One review of 45 controlled trials found no difference in behavioural disinhibition between benzodiazepines and placebo. A 1988 review put aggressive dyscontrol at under 1% and similar to placebo. A 1994 alprazolam trial found paradoxical reactions in 13.7% against none on placebo, and a 1985 trial in borderline personality disorder found 58% against 8%. The drug, the population and the study all change the answer. That is part of why nobody can give a figure for Selank.
Does Selank cause low mood?
Low mood appears in community accounts and is not described in the published trial abstracts. Those abstracts summarise rather than tabulate adverse events, and the full texts are in Russian.
Is Selank approved anywhere?
Not in the United States, the United Kingdom or the European Union. It was developed and trialled in Russia, where the published trials describe it as an anxiolytic in clinical use. We have not read a regulatory document confirming its registration status there, so none is stated here.
Should I stop if it is making me feel worse?
That is a reasonable thing to do while you work out what is happening, and nothing in the trials describes a withdrawal effect from Selank itself. A prescribed medicine is different and needs a clinician's plan. If anxiety or low mood is severe or persistent, that needs a clinician rather than a decision about a vial.
Sources
- Zozulia AA, Neznamov GG, Siuniakov TS, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2008. PMID 18454096. Comparative clinical study in 62 patients with generalised anxiety disorder and neurasthenia, 30 receiving selank and 32 medazepam, assessed on psychometric scales alongside serum enkephalin activity. The English abstract reports that the anxiolytic effects of both drugs were similar and that selank also had antiasthenic and psychostimulant effects, and describes the blood half-life of leu-enkephalin as shortened at baseline and lengthened during treatment. No placebo arm. Full text in Russian; read via the English abstract.
- Medvedev VE, Tereshchenko ON, Israelian AI, et al. A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders. PMID 25176261. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2014. Comparative study in 60 patients with phobic-anxiety and somatoform disorders, ICD-10 F40.2-9, F41.1-9 and F45.0-1. The English abstract reports pronounced anxiolytic and mild nootropic effects of selank, states that in contrast to phenazepam selank did not exert objectionable side effects, and describes the anxiolytic effect being retained and in some cases increasing after treatment stopped. No placebo arm. Full text in Russian; read via the English abstract.
- Medvedev VE, et al. Optimisation of the treatment of anxiety disorders with selank. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2015. PMID 26356395. Add-on study in 70 patients with anxiety disorders, 30 receiving phenazepam alone and 40 phenazepam with selank. The English abstract reports that the combined treatment decreased the level of undesirable side effects of phenazepam. No placebo arm. Full text in Russian; read via the English abstract.
- Peptide Decoding vendor price capture, 11 October 2026. peptidedecoding.com/prices. Our own data, counting one priced product at one seller as a listing. Selank appears in 159 listings across 102 sellers: 142 vials, 8 nasal sprays, 1 tablet, 7 sprays, 1 solution.
- Paton C. Benzodiazepines and disinhibition: a review. Psychiatric Bulletin 2002;26(12):460-462. doi:10.1192/pb.26.12.460. Open access; full text read at source. Medline search 1966 to January 2002. Lists disinhibition behaviours as "increased anxiety, vivid dreams, hyperactivity, sexual disinhibition, hostility and rage". States the overall incidence of disinhibitory reactions is small and that "because overt rage reactions are rare, they are difficult to quantify". Rates quoted in the review, each from the primary study named: Greenblatt et al. 1984, across 45 controlled trials, found no difference in the incidence of behavioural disinhibition between triazolam, flurazepam and placebo; Dietch and Jennings 1988 found "the incidence of aggressive dyscontrol after administration of a benzodiazepine is less than 1%" and "similar to the incidence with placebo"; O'Sullivan et al. 1994 found "13.7% of patients randomised to alprazolam experienced paradoxical reactions compared with none given placebo"; Gardner and Cowdrey 1985, in borderline personality disorder, found "58% of patients randomised to alprazolam experienced paradoxical reactions compared with 8% with placebo"; published alprazolam case series put disinhibition at 10 to 20% of patients. Cassano et al. 1994 found no difference in aggressive behaviour between imipramine and alprazolam in 1,168 patients, which is an active comparison rather than a placebo one. Risk groups named in the abstract: "those with impulse control problems, neurological disorders, learning disabilities, the under 18s and the over 65s". The primary studies are cited here as the review reports them and were not read individually. Cited as established for the benzodiazepine class, which is the comparator in all three Selank trials, and not as evidence about Selank.
- Mancuso CE, Tanzi MG, Gabay M. Paradoxical reactions to benzodiazepines: literature review and treatment options. Pharmacotherapy 2004;24(9):1177-1185. PMID 15460178. doi:10.1592/phco.24.13.1177.38089. Published abstract confirmed through the Europe PMC bibliographic record: paradoxical reactions including increased talkativeness, emotional release, excitement and excessive movement are "relatively uncommon" and occur in "less than 1% of patients"; the mechanism is unclear; most cases appear idiosyncratic, with some evidence linking them to a genetic factor, a history of alcohol abuse, or psychological disturbances. Note that the behaviours this review lists are excitement-type reactions in a sedation context, which is a narrower set than the 2002 review's list.
Citing this page. Peptide Decoding. Can Selank Make Anxiety Worse? Trial details from the published English abstracts; listing data from the 11 October 2026 capture. https://peptidedecoding.com/guides/can-selank-worsen-anxiety