Two peptides, one Moscow institute, one shared design trick, and almost nothing else in common.
Semax and Selank both came out of the Institute of Molecular Genetics at the Russian Academy of Sciences. Both are seven amino acids long. Both solve the same engineering problem the same way, by bolting a Pro-Gly-Pro tail onto a short natural fragment so enzymes cannot shred it in the first few minutes. From a chemist’s angle they are siblings.
From a user’s angle they are not interchangeable, and the number of people who buy the wrong one is the reason this page exists.
Every comparison you will read frames it the same way. Semax is the BDNF one for focus. Selank is the GABA one for anxiety. Clean, tidy, easy to remember. It is also an oversimplification that falls apart the moment you read the studies that dosed both compounds in the same animals, which almost nobody writing about this pair has done.
That research is in here, along with the part nobody mentions: which one you inject or spray changes which effect you get. So does your own baseline. Selank has three trials against actual benzodiazepines, which is a harder test than anything else in this category has faced. Semax has a July 2026 vote from an FDA advisory committee that Selank never got, and the reason behind that gap is not what most sites assume.
Which One You Need, in One Question
Before mechanisms, before trials, before vial sizes, answer this. On a bad day, what stops you?
If the answer is that you sit down, the work is right there, and you cannot make yourself engage with it, that is a Semax problem. Focus, verbal fluency, and the willingness to start are what people report from it.
If the answer is that you are wound tight, the room feels loud, and your attention is going to a low hum of worry instead of the task, that is a Selank problem. No amount of focus peptide fixes a nervous system running hot. It usually makes it worse.
That second failure mode accounts for most of the bad first experiences people report with Semax, and there is now animal data pointing at exactly the same thing. More on that below. Someone already keyed up who reaches for a focus compound is adding energy to a system that has too much of it.
A large number of people answer yes to both questions. That is what the stack section is for, and it is why these two get sold together. It is also not a reason to start both at once.
Semax: What the Focus Side Rests On
Semax is a fragment of ACTH with a Pro-Gly-Pro tail attached. Full ACTH triggers cortisol release. The fragment keeps the neural activity and loses the hormonal signal, which is why a compound descended from a stress hormone does not behave like one.
A detail worth getting right, since almost every page gets it wrong. Semax is usually described as ACTH(4-10) with PGP added. Count the residues and that cannot work. ACTH(4-10) is seven amino acids by itself. Semax is the ACTH(4-7) fragment plus the three-residue tail, four and three making seven. The literature does call it an ACTH(4-10) analog, and that shorthand is defensible, but the arithmetic version tells you whether a page was built from sources or from other pages.
Its reputation rests on BDNF. Dolotov and colleagues in Brain Research gave rats one intranasal dose at 50 micrograms per kilogram and measured hippocampal BDNF protein up 1.4-fold, TrkB phosphorylation up 1.6-fold, and BDNF messenger RNA up threefold. From a single dose, which is why people notice something on day one rather than week three.
The monoamine picture deserves more care than it gets. Eremin and colleagues, in Neurochemical Research in 2005, is the paper cited everywhere for “Semax raises dopamine.” Read it and that is not what happened. Striatal serotonin metabolites climbed steadily to 180% of baseline over four hours. Dopamine did not move at all when Semax was given alone. A dopaminergic effect appeared only when Semax preceded amphetamine, where it amplified the release sharply.
Semax modulates the dopamine system rather than driving it. That explains both why users describe drive without a stimulant signature, and why layering it onto a prescribed stimulant belongs in a conversation with a prescriber.
On the human side, the deepest file is stroke. Gusev and colleagues followed 110 patients through rehabilitation at 6,000 micrograms daily in two ten-day courses, and the Semax groups showed markedly larger gains in BDNF and Barthel index scores than controls. It is open-label with no placebo arm and Semax was added to standard therapy rather than tested alone, so read it as supportive rather than definitive.
Selank: What the Calm Side Rests On
Selank starts somewhere stranger. Tuftsin is a four-residue fragment of an antibody, part of the immune system’s signaling toolkit, discovered at Tufts University. Add the same Pro-Gly-Pro tail and you get an anxiolytic. Nobody would have predicted that from the parent molecule.
Russia registered it in 2009 as nasal drops at 0.15%, and it moved to over-the-counter status in 2017. The approved label is broader than the trial populations, covering anxiety states, unmotivated worry, asthenia, mood lability, sleep disturbance, and adjustment and stress disorders in adults.
Now the mechanism, with a correction attached. You will read everywhere that Selank is a positive allosteric modulator at the GABA-A receptor, stated as fact, sometimes described as working like a benzodiazepine without the downsides. No binding study or electrophysiology work demonstrates that. Selank does not bind the benzodiazepine site. The allosteric language comes from the discussion sections of gene-expression papers, where researchers offered it as a plausible reading of what they were seeing.
What they were seeing is more interesting than the simplified version. Volkova and colleagues, in Frontiers in Pharmacology in 2016, gave rats a single intranasal dose and measured 84 neurotransmission-related genes in frontal cortex. Forty-five had shifted within one hour. More telling, the pattern Selank produced correlated with the pattern produced by GABA itself at r equals 0.86. Selank was not behaving like a GABA drug. It was producing a GABA-shaped fingerprint.
Selank also slows the enzymes that degrade enkephalins, an effect it shares with Semax, and one that showed up in patients as well as in serum experiments.
Where the Clean Split Breaks Down
Every comparison article sells the same tidy division. Semax works on BDNF, Selank works on GABA, pick according to your problem. It is a useful starting frame and it is not what the research shows once you look at studies that tested both compounds under the same conditions.
One research group in Moscow has spent years doing exactly that, and their results are absent from every competing page on this topic.
Semax raises GABA-A receptor density
Start with the finding that should complicate anyone’s mental model. Vasileva and colleagues, in the Neurochemical Journal in 2021, gave BALB/c mice subchronic Semax and measured GABA-A receptor density in prefrontal cortex using radioligand binding. Injected Semax raised it by 68%. Intranasal Semax raised it by 37%.
The focus peptide, in other words, producing a substantial change in the receptor system the calm peptide is supposed to own. In C57BL/6 mice the effect was minimal, which is a separate point worth holding onto.
The traffic does not run only one way. Selank has its own published work on BDNF in the hippocampus, and a 2019 study in the Bulletin of Experimental Biology and Medicine found Selank normalizing BDNF levels that ethanol had disturbed. The accurate statement is that Selank modulates BDNF rather than simply raising it, which is still enough to break the neat division.
Both hit the same NMDA target
The same group went further. A 2023 study measured the glycine site of the NMDA receptor after Selank, Semax and Noopept in both mouse strains. Given intranasally, all three reduced cortical glycine sites, by 18% for Selank and 66% for Semax in BALB/c mice. In the hippocampus of the same strain, the numbers went the other way, rising 15% for Selank and 95% for Semax.
The authors read the cortical pattern as something these compounds share. Same target, same direction, different magnitude. Not two separate mechanisms sitting in separate lanes.
The route decides which effect you get
This is the finding with the most practical weight, and nobody comparing these two has written about it.
Vasileva and colleagues in 2020 ran Selank, Semax and Noopept through BALB/c and C57BL/6 mice by two routes, injection and intranasal, testing both anxiety and cognitive performance. In BALB/c mice the pattern was clean and unexpected. Anxiolytic efficiency was higher after injection. Nootropic efficiency was higher after intranasal dosing.
Same compound. Same dose. Different route, different dominant effect.
There is a second detail in that paper worth stating carefully. In C57BL/6 mice, injected Semax showed a greater anxiogenic effect than intranasal Semax did. That is a comparison between two routes rather than a finding that injected Semax made mice anxious outright, so it should not be overstated. It does line up uncomfortably well with the most common complaint about Semax among people who already run anxious.
Three practical implications follow. Choosing between these compounds is not the only decision that matters, because how you take them shapes what you get. If focus is the goal, the animal data favors the nasal route, which happens to be the route every human study used. And if you are anxiety-prone and considering Semax, the route may matter more for you than for anyone else.
Mouse strain mattered throughout all three studies, which is a reminder that individual response varies for reasons nobody can predict from a product page. BALB/c mice are the anxious strain. C57BL/6 are not. The compounds behaved differently in each.
Selank’s Trump Card: The Benzodiazepine Trials
This is the part of the comparison that should decide it for a lot of readers, and most pages bury it under mechanism talk.
Selank was not tested against placebo in a corner. Russian researchers put it directly against benzodiazepines in patients, three separate times.
Zozulya and colleagues ran 62 patients with generalized anxiety and neurasthenia, thirty on Selank and thirty-two on medazepam. Anxiety reduction was comparable between them. The difference showed up alongside it, with the Selank group picking up activating and anti-asthenic effects the benzodiazepine did not produce. Enkephalin levels rose in both groups, more so with Selank, and patients had shown shortened enkephalin half-life at baseline that tracked with symptom severity.
A second study put Selank against phenazepam across 60 patients with anxiety-phobic and somatoform disorders, 2.7 mg daily of each for fourteen days. Anxiety relief was comparable again, tolerability was better, and the Selank benefit was still measurable a week after the last dose. Phenazepam’s effect dropped away quickly once stopped, and it impaired Stroop test performance while Selank did not.
The third is the one that keeps getting discussed. Seventy patients, forty receiving phenazepam plus Selank together against thirty on the benzodiazepine alone. The combination produced an earlier response and specifically reduced the benzodiazepine’s characteristic downsides: impaired attention and memory, asthenia, and sedation. Quality-of-life scores improved and coming off the benzodiazepine was easier.
Taken together, Selank has the strongest anxiolytic evidence of anything sold as a research peptide.
The limitations deserve the same airtime, because the pages that oversell this are doing readers no favors. All three were open-label rather than blinded. All were run in one country, several by the institute that developed the compound, and published in Russian-language journals with only English abstracts indexed. The largest enrolled seventy people. Against a Western Phase III program this is not close. Against the forum reports most compounds in this space run on, it is a different category entirely.
Two things that third study is not. It is not permission to taper a prescription on your own, and it is not evidence that Selank prevents dependence. It showed that adding Selank made a benzodiazepine easier to tolerate and easier to stop under medical supervision. Anyone on a prescribed benzodiazepine should take that paper to their prescriber rather than acting on it.
Two jobs, one lab, one code
Base Semax and base Selank, made in-house in California
These are the unmodified molecules the Russian literature was built on, not the acetylated and amidated variants with no clinical file behind them. Paramount has synthesized its own peptides in Irvine, California for over 12 years, tests every lot at a named third-party lab with the COA history posted on the page, and refunds your order plus the $100 testing fee if a vial ever fails HPLC.
Focus
Semax 30mg
$68, about $57.80 with code. Close to four full courses in one vial, at roughly $1.93 per milligram.
Calm
Selank 5mg or 10mg
$51 or $68. Sized to a fourteen-day course: the 5mg at 300 micrograms a day, the 10mg at 600.
Code BRAINFLOW takes 15% off either one. Research use only. Free shipping over $300.
How Fast They Work and How Long They Last
No competing comparison answers this, and it explains the dosing schedules better than anything else does.
Shevchenko and colleagues tracked radiolabeled Semax after intranasal dosing in rats. Two minutes after administration, the compound was in the brain. Roughly 80% of what they detected there was intact Semax rather than breakdown products. After that the peptide degrades quickly, with the Pro-Gly-Pro fragment coming to dominate the samples.
Two minutes to the brain, then rapid clearance. That single result explains most of what confuses people about these compounds.
It explains why users report noticing something within the first hour rather than after weeks of loading. It explains why Russian protocols dose two or three times a day instead of once. And it explains why a peptide that clears this fast can still produce effects lasting well beyond its own presence in tissue, because what Semax leaves behind is altered gene expression and protein levels rather than a drug sitting on a receptor. Dolotov measured BDNF changes hours after the peptide itself would have been gone.
The same logic covers Selank, whose anxiolytic benefit in the phenazepam trial was still measurable a week after the last dose. A compound that clears in hours cannot be producing a week-long effect by still being present. It is producing it by having changed something.
Worth knowing that the two-minute figure comes from nasal dosing, and no equivalent kinetic study exists for either compound given subcutaneously.
What a course tends to feel like
Composite from community reports rather than trial data, and worth treating as a map of expectations.
Semax often announces itself on the first session, with a meaningful share of people reporting easier sentences and less friction starting work within twenty to forty minutes. Others feel nothing until day two or three. By the end of the first week the reports converge on verbal fluency and staying on task. Week two is where a steadier baseline shows up, described more often as feeling like a good version of your normal self than as feeling altered.
Selank tends to be slower and quieter. The common pattern is a few days before background worry noticeably drops, with the effect building across the first week and holding through a fourteen-day course. Fewer people report a dramatic first session with Selank than with Semax, which fits a compound whose job is subtraction rather than addition.
A minority feel nothing from either. With peptides specifically, a dead vial from a poor vendor is the first thing to rule out before concluding the compound does not work for you.
Why Semax Got an FDA Vote and Selank Did Not
Something happened in 2026 that splits these two apart, and every comparison article currently ranking for this topic either misses it or describes a meeting that already happened in the future tense.
In September 2023 the FDA placed nineteen peptides into 503A Category 2, the designation for bulk substances flagged as carrying significant safety risks for compounding. Both Semax and Selank were on that list, Selank appearing as “Selank acetate (TP-7).”
Their paths diverged from there. Selank left Category 2 when its nominators withdrew the nomination, which removed it from the risk list without advancing it toward anything. Semax stayed in the process. In April 2026 the FDA moved twelve peptides out of Category 2 and referred them for formal advisory review, Semax among them.
That review happened on July 23 and 24, 2026. The Pharmacy Compounding Advisory Committee worked through seven peptides. On the second day the panel backed Semax by 8 votes to 5 with one abstention, covering both the free base and the acetate, for cerebral ischemia, migraine and trigeminal neuralgia. It also backed Epitalon and rejected emideltide. The day before it had backed BPC-157, KPV, TB-500 and MOTS-c. In every case the committee voted in favor over the written objections of the FDA’s own scientific staff.
Selank was not on the agenda for either day.
Its current position gets stated incorrectly almost everywhere, including by pages that claim both peptides are barred from compounding. Selank is no longer listed in Category 2, which sounds like progress and is not. Its nomination was withdrawn rather than decided. It received no vote, has no review scheduled, and sits on neither list. A compounding pharmacy cannot legally prepare it, and nothing is currently in motion that would change that.
For Semax the door is at least open, with limits worth being precise about. A favorable advisory vote is a recommendation. The FDA is not bound by it, formal rulemaking has not started, and that process typically runs six months to two years once it does. Semax is not legally compoundable today. Nothing about buying either compound changed on July 25.
WADA, and the Detail Everyone Gets Wrong
Tested athletes get told one of two things about these peptides, and both are imprecise.
Neither Semax nor Selank appears by name on the 2026 WADA Prohibited List. That much is agreed. The disagreement is over S0, the catch-all category for non-approved substances, which several pages state flatly captures both.
The exact wording matters here more than anywhere else in this article. S0 covers any pharmacological substance “with no current approval by any governmental regulatory health authority for human therapeutic use.” Some pages quote it as “any major governmental regulatory health authority.” The word major does not appear in the list.
That omission changes the analysis. Semax and Selank both hold marketing authorization from Russia’s Ministry of Health for human therapeutic use. Semax has been on Russia’s List of Vital and Essential Drugs since December 2011. Russia’s Ministry of Health is a governmental regulatory health authority. On a literal reading of the text, S0 does not obviously capture either compound.
Read that as a textual argument rather than a compliance assurance, and the distinction is important enough to spell out. Anti-doping runs on strict liability, testing authorities interpret the list themselves, and no athlete has ever been served well by a clever reading of a rule. Anyone subject to testing who wants to use either compound should get a written ruling from their national anti-doping organization rather than relying on this paragraph or any other.
Running Semax and Selank Together
The stack is common enough that people ask about it before trying either compound alone, which is the wrong order.
The pattern that holds up in community reports is Semax in the morning, Selank later in the day or on days when the edge shows up. Both cycled rather than run continuously. Semax responds poorly to daily use without breaks, and the effect reportedly flattens.
Three to five days on each one separately before combining is the advice worth taking. If something goes sideways, a headache or irritability or a day that felt wrong, you want to know which vial produced it. Start both at once and you have no way to tell.
Once you know your response to each, taking both the same morning is normal and the spacing stops mattering much. The separation is diagnostic rather than pharmacological.
There is a mechanistic wrinkle worth knowing given what came out of the head-to-head work above. If Semax is raising GABA-A receptor density on its own, then a Semax plus Selank stack is not two unrelated compounds working in separate systems. It is two compounds with overlapping effects on the same receptor family, which is an argument for building up slowly rather than assuming they cannot interact.
Combinations people ask about
Semax alongside a full pot of coffee is where most of the jittery reports originate. Selank with caffeine is usually uneventful and is the pairing anxious coffee drinkers tend to like.
Semax with modafinil produces an oddly consistent number of reports of getting sleepy, which nobody has explained.
Prescribed stimulants deserve real caution with Semax specifically, and not on general principle. Eremin found that Semax on its own did nothing to dopamine but sharply amplified amphetamine-induced dopamine release when given beforehand. That is a documented interaction with the exact drug class millions of people take for ADHD, and it belongs in a conversation with the prescriber rather than a self-experiment.
SSRIs and other antidepressants come up constantly and have no published interaction data with either peptide. Semax raises serotonin metabolites in animals, which is a theoretical reason for caution when combined with a drug that also acts on serotonin, though theoretical is the operative word. Nobody has studied it. Anyone on an antidepressant should treat that absence of data as a reason to ask a clinician rather than a green light.
Benzodiazepines are the one combination with actual human data, and it is favorable. The Medvedev study found adding Selank to phenazepam reduced the benzodiazepine’s side effects. That still belongs under medical supervision, since the patients in that study were supervised.
Semax, Selank, and ADHD
A large share of people searching this comparison are asking an ADHD question without typing the word, so it deserves a direct answer.
Neither compound has been trialed for ADHD. No study exists in either direction, in Russia or anywhere else. Anybody presenting one of these as an alternative to a prescribed stimulant is working from mechanism and anecdote.
What can be said fairly is this. Russia’s registered Semax label does include memory and attention disorders as an indication, and does approve pediatric use from age seven, so the attention framing is not invented from nothing. Community reports from people with ADHD diagnoses skew positive on Semax for task initiation and verbal work specifically, which are the domains the peptide gets described in generally.
The mechanism argument cuts in an interesting direction. Stimulants work by increasing dopamine availability. Semax does not do that on its own, which means it is not a weaker version of the same drug. It is a different intervention that happens to affect some of the same outcomes, and the Eremin finding about amplified amphetamine response suggests it interacts with that system rather than substituting for it.
For the inattentive presentation, where anxiety often sits underneath the attention problem, Selank is worth considering before Semax rather than after. Treating an anxiety-driven attention problem with a focus compound is the most common way people have a bad experience here.
Nothing in this section is a substitute for an actual ADHD assessment or a reason to change a prescription.
What Each One Does to Sleep
The two compounds behave oppositely here and it is the most practical difference in daily use.
Anything after mid-afternoon with Semax tends to still be working at bedtime. Disrupted sleep is the single most common complaint in community reports, and it is almost entirely a timing problem rather than a compound problem. Keeping it before mid-afternoon solves it for most people.
Selank carries no such restriction and is often taken deliberately in the evening. Better sleep shows up frequently in reports, though the mechanism people describe is indirect. Selank is not sedating and does not knock anyone out. What it appears to do is quiet the looping worry that keeps people awake, which produces better sleep as a consequence rather than as a direct effect. Russia’s registered label lists sleep disturbance among the conditions it covers.
For anyone running the stack, this is the strongest argument for the morning-and-evening split rather than taking both at once.
Dosing, Conversions, and the Route Question
Both compounds were developed as nasal drops and both were studied that way. Every Selank trial above used the intranasal route at 2.7 mg per day of the 0.15% solution. Every Semax study did the same. No published efficacy data exists for either one given subcutaneously.
Community practice with reconstituted research vials splits between nasal dosing and subcutaneous injection. The argument for injecting is higher absorption. The arguments against are that nasal delivery gives small peptides a partial direct path into the central nervous system, that Shevchenko measured intact Semax in brain tissue two minutes after nasal dosing, and that the Vasileva route comparison found nootropic effects stronger by the nasal route in the strain where both were tested.
Nobody has measured the tradeoff directly in humans for either compound. What can be said is that if you want to replicate the research, the research used the nose.
Oral is a dead end for both. Peptide bonds do not survive digestion and no study of either compound has used that route.
Converting Russian percentages into micrograms
Russian sources describe doses as percentage solutions and drop counts. Research vials are sold in milligrams. The two never get bridged anywhere, which leaves people unable to compare a clinical protocol to what is in their fridge.
The arithmetic is simple once you know the drop volume, which the Semax label states as 0.05 mL.
The Selank figure is a calculation from the stated concentration and the standard drop volume rather than a number printed on the box, so treat it as an estimate. It does line up sensibly with the trial dosing, where 2.7 mg daily was used at a higher concentration.
Community practice with research vials runs well below both. Most reports for either compound sit between 300 and 600 micrograms a day, which puts recreational use at roughly a third to two thirds of the registered Selank regimen and at the bottom of the registered Semax range.
Reconstitution math for research vials
Selank is the easy one. Two millilitres of bacteriostatic water in the 10mg vial gives 5 mg per millilitre, putting 300 micrograms at 6 units on a U-100 syringe, 600 at 12 units, and 900 at 18. One millilitre in the 5mg vial lands at the same concentration and the same chart. Comfortable, readable measurements.
The 30mg Semax vial needs its own chart. The same 2 mL gives 15 mg per millilitre, so 300 micrograms is 2 units, 600 is 4 units, and 900 is 6. Those are small draws where a one-unit slip at the 600 mark is a 25% error, so if you want more room to read the syringe, use 3 mL instead. That gives 10 mg per millilitre, with 300 micrograms at 3 units, 600 at 6, and 900 at 9. Never reuse the Selank chart on the Semax vial, since at the same water volume the concentration is threefold higher.
Label every cap with the vial size and the water volume the day you mix it.
Side Effects, and the One That Differs
Both are quiet compounds by the standards of anything else people take for focus or anxiety. Neither has a withdrawal profile, neither is sedating, and the Russian clinical record on both runs long.
Semax has the better-documented adverse event profile, since it has been prescribed longer. The Alzheimer’s Drug Discovery Foundation’s review of the compound reports nasal cavity discoloration in roughly 10% of patients and elevated blood glucose in around 7.4% of diabetic patients. The first follows from years of nasal dosing. The second is worth knowing for anyone managing blood sugar.
Beyond that, both produce the same short list. Headache in the first few days, irritability in anyone who opened at the top of the range rather than building up, and local irritation from whichever route you use. Most of it tracks with dose.
The sleep difference covered above is the practical divider. Semax late in the day costs you the night. Selank does not.
Selank has one consideration Semax does not, and it comes from the tuftsin lineage. Tuftsin is an immune-signaling peptide, and while Selank is not tuftsin, anyone with an autoimmune condition should treat that ancestry as relevant rather than as trivia and talk to a clinician first.
Neither has modern Western long-term safety data. Decades of Russian prescribing is reassuring and it is not a substitute for controlled follow-up in healthy adults using these for focus and calm.
Base Molecules Versus N-Acetyl and Amidated Versions
Both compounds are sold in modified variants, usually marketed as stronger or longer lasting. N-Acetyl Semax Amidate is the best known, often shortened to NASA, and N-Acetyl Selank Amidate exists alongside it. A surprising number of US buyers end up with one of these without realizing it is not the compound the research used.
The chemistry is sound. Blood enzymes attack both peptides from the N-terminus, taking the first residue, so capping that end with an acetyl group blocks the opening move directly. Amidating the far end closes the remaining exposure. Published work gives the amidated Semax variant roughly thirty extra minutes of resistance to one degrading enzyme.
Thirty minutes of stability is not a potency multiplier. No head-to-head study of any modified version against its base molecule exists on any efficacy endpoint, for either compound. Figures circulating online, whether two times or five times stronger, trace back to vendor pages and nothing further.
Everything described in this article, the benzodiazepine trials, the BDNF measurements, the receptor density work, the stroke rehabilitation results, the Russian registrations, was done with base Semax and base Selank. Buying the molecules the evidence was built on is the sensible default, and they usually cost less.
What Each One Costs to Run
Nobody comparing these two prices them, which is strange given that cost is the reason most people pick one to start with.
At 600 micrograms a day, a 10mg Selank vial covers about sixteen days, which is one full course with a little left over. At $68, or $57.80 with code BRAINFLOW, that is roughly $3.60 a day. The 5mg Selank at $51 ($43.35 with code) covers the same fourteen days at 300 micrograms, the lower end of where community practice sits.
The two diverge over a year. Selank tends to be used in defined courses when something is going on, so a couple of vials often covers twelve months. Semax gets run repeatedly by people who like it, and four fourteen-day courses a year at 600 micrograms comes to about 34mg. One 30mg Paramount vial covers all but the last few days of that. At $68, or $57.80 with the code, a year of Semax works out to about $1.16 per dosing day.
That is why Semax is the one sold in a big vial and Selank is not. Per milligram, the 30mg Semax works out to about $1.93 with the code against $5.78 for the 10mg Selank, and the gap is a sizing decision rather than a pricing one. Selank is meant to be bought a course at a time. Semax is meant to be bought once and run all year.
Buying Semax and Selank
The requirements are the same for both. A named third-party lab, a Certificate of Analysis readable before you pay, milligram content on the vial, and base molecules rather than modified variants. Walk away from blended nasal sprays combining acetylated versions of both, which are a different product from anything in the research record.
Paramount Peptides is where we send readers for both, and the reason is where the vials come from. Paramount has synthesized its own peptides in-house in Irvine, California for over 12 years. The Semax and Selank you get were made, purified, and QC’d under one roof rather than relabeled from an overseas supplier, which is not the norm in this market.
Both are base molecules at 99% or better purity by HPLC, with a third-party COA posted on the product page and the lot history behind it, Janoshik on the Semax and Accumark Labs on the Selank. If a vial ever fails an HPLC test at a licensed lab, Paramount refunds the order and the $100 testing fee. Semax runs $68 for 30mg. Selank is $51 for 5mg and $68 for 10mg. Code BRAINFLOW takes 15% off, and checkout is a normal card checkout.
One piece of practical advice on sizing. If you are buying both, take Selank in the 10mg and Semax in the 30mg. A 10mg Selank vial covers a full fourteen-day course at 600 micrograms with room to spare, and the 5mg does the same at 300, which is why nothing larger exists. Semax is the compound people run repeatedly, as the full Semax guide goes into, and the 30mg vial is where the savings live.
Buy the pair, size them differently
Selank in the 10mg. Semax in the 30mg.
A 10mg Selank vial covers a full fourteen-day course, so anything larger would sit in your fridge degrading. Semax is the one people run four times a year, and one 30mg vial at about $1.93 per milligram with the code covers close to all four. Same in-house Irvine synthesis on both, same third-party COA before checkout, same purity refund guarantee, same code.
Get the 30mg Semax → Get the Selank 10mg →Code BRAINFLOW takes 15% off either. Research use only. Made in the USA, ships from California.
Common Questions About Semax and Selank
Which should I try first?
Whichever matches your actual bottleneck. Semax if you cannot engage with work sitting in front of you. Selank if background anxiety is eating the attention you would otherwise spend on it. Anyone who runs anxious by default is usually better served starting with Selank, since a focus compound layered onto an overactive nervous system tends to read as agitation.
Can you take Semax and Selank together?
Yes, and the combination is common. Run each alone for three to five days first so you can attribute any effect or side effect to the right vial. After that, Semax in the morning and Selank later in the day is the usual pattern, and taking both in the same morning is fine once you know how you respond.
Is Selank as effective as a benzodiazepine?
Three Russian trials compared it directly to medazepam and phenazepam and found comparable anxiety reduction with better tolerability, no sedation, and benefit persisting about a week after stopping. Those studies were open-label and single-country, so this is not equivalent to an approved drug, and Selank is not an FDA-approved substitute for anything. Nobody should adjust a prescription based on it.
Is Selank really a GABA-A modulator?
That is a hypothesis rather than a demonstrated fact. No binding or electrophysiology study shows Selank acting at the GABA-A receptor, and it does not bind the benzodiazepine site. What exists is gene-expression work in rat cortex where Selank’s signature correlated with GABA’s own at r equals 0.86, which researchers proposed might reflect allosteric modulation. The effect is real. The receptor-level explanation is unconfirmed.
Does Semax work on GABA too?
Apparently yes, which complicates the usual framing. A 2021 study found subchronic Semax raising GABA-A receptor density in the prefrontal cortex of BALB/c mice by 68% when injected and 37% intranasally. Selank was not tested in that particular study, so this is Semax reaching into territory usually assigned to Selank rather than the reverse.
Does the route of administration change the effect?
In mice it does, substantially. A 2020 study running both compounds by two routes found anxiolytic effects stronger after injection and cognitive effects stronger after intranasal dosing in BALB/c mice. Nobody has replicated this in humans, but it is a reason to favor the nasal route if focus is the goal, which is also the route every human study used.
Can Semax make anxiety worse?
It is the most common complaint from people who already run anxious, and there is animal data pointing the same way. In C57BL/6 mice, injected Semax showed a greater anxiogenic effect than the same dose given intranasally. That is a route comparison rather than proof Semax causes anxiety, but anyone prone to it should start low and consider the nasal route.
How fast does Semax reach the brain?
Two minutes after intranasal dosing in rats, with around 80% of what was detected in brain tissue being intact Semax rather than metabolites. It clears quickly afterward. That combination of fast onset and fast clearance is why Russian protocols dose multiple times a day and why effects can outlast the peptide’s presence, since what it leaves behind is changed gene expression rather than a drug on a receptor.
Can I use Semax or Selank for ADHD?
Neither has been trialed for ADHD and neither is a substitute for prescribed treatment. Russia’s Semax label does include memory and attention disorders, and community reports from people with ADHD diagnoses skew positive on Semax for task initiation. Where anxiety sits underneath the attention problem, Selank is worth trying first. Anyone on a prescribed stimulant should raise Semax with their prescriber, since it amplifies amphetamine-induced dopamine release in animals.
Do Semax or Selank affect sleep?
Oppositely. Semax is activating and a late dose commonly disrupts sleep, which keeping it before mid-afternoon usually fixes. Selank has no timing restriction and frequently improves sleep indirectly by quieting the worry that keeps people awake rather than by sedating them. Russia’s Selank label includes sleep disturbance among its indications.
Can I take them with an SSRI?
No interaction data exists for either compound with antidepressants. Semax raises serotonin metabolites in animals, which is a theoretical reason for caution alongside a serotonergic drug, though nobody has studied it. Treat the absence of data as a reason to ask a clinician rather than as reassurance.
Is N-Acetyl Semax Amidate better than regular Semax?
No study has compared them. The modifications improve laboratory stability by roughly thirty minutes against one enzyme, which is real but is not a potency multiplier. Every study cited in this article used base Semax. The same applies to N-Acetyl Selank Amidate.
How long should a cycle be?
Russia’s Selank label specifies fourteen days, repeatable after one to three weeks. Semax community practice runs ten to fourteen days on with a similar break, borrowed from the Russian outpatient charts. Continuous daily Semax is the most common reason people report the effect fading.
Why does Semax come in 30mg and Selank in 5mg and 10mg?
Usage patterns. Selank tends to be run in defined fourteen-day courses, and Paramount sizes it to match: the 5mg covers a course at 300 micrograms a day, the 10mg covers it at 600. Semax is used repeatedly across the year, so the 30mg vial solves a real cost problem, covering close to four courses on its own at about $1.93 per milligram with the code.
Did the FDA approve either one in 2026?
Neither. An advisory committee recommended Semax for the 503A compounding list on July 24, 2026, by 8 votes to 5 with one abstention. That is a non-binding recommendation awaiting formal rulemaking, not an approval, and Semax is not legally compoundable today. Selank was not reviewed at all, its nomination was withdrawn, and it sits on neither list.
Are they banned by WADA?
Neither is named on the 2026 Prohibited List. The S0 catch-all covers substances with no approval from any governmental regulatory health authority, and both hold Russian marketing authorization, so a literal reading of the text does not clearly capture them. That is an argument rather than a guarantee. Strict liability applies and testing authorities interpret the list themselves, so get a written ruling from your anti-doping organization before relying on it.
Where can I buy them?
We point readers to Paramount Peptides for both. They carry base Semax in 30mg and base Selank in 5mg and 10mg, all synthesized in-house in Irvine, California, tested at 99% or better purity by HPLC with the third-party COA posted before purchase, and backed by a purity refund guarantee. Code BRAINFLOW takes 15% off either.
Picking Between Them
These two get compared constantly because they look alike on paper and came from the same building. Almost nobody who has run both thinks of them as alternatives.
Semax is the one with the neurotrophic story, the BDNF data, the stroke file, and now a federal advisory committee willing to vote for it. Selank is the one with three trials against real benzodiazepines, a harder test than almost anything else in this category has faced, and a considerably worse regulatory position in the United States to show for it.
The tidy mechanism split everyone sells is a useful starting point and not the full picture. Semax raises GABA-A receptor density. Selank modulates BDNF. Both act on the same NMDA glycine site. And the route you choose shifts which effect dominates, at least in mice. These are overlapping tools with different centers of gravity, not two switches wired to separate systems.
Pick by the problem rather than by the evidence file. The best-supported compound for anxiety does nothing for an unfinished brief, and the best focus peptide in the world makes a bad week worse if the week is bad because you are wound tight.
If both descriptions fit, run them separately for a few days each before combining. And buy base molecules you can verify. Paramount carries both, made in-house in California with a third-party COA on the page, and code BRAINFLOW takes 15% off.
Semax and Selank are sold in the United States as research peptides for laboratory use only and are not FDA-approved. Amounts described here come from published research and Russian registered labels as context, not as instructions. This article is educational and is not medical advice. Consult a qualified clinician before beginning any protocol, and never adjust a prescribed medication without medical supervision.
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Last updated September 2026.
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