Semax

N-Acetyl Semax

Checked Oct 28, 2026

The short answer

No human evidence yet for focus, memory and stress resilience in healthy adults

Grade D for focus in healthy adults: no trial we could verify measured cognitive performance in healthy people, and the one placebo-controlled study (24 adults) looked at a brain-imaging network.

Approved?: Not approved for any use.
Safety: C, thinly characterized: Small Russian studies report mild nasal irritation and headache, and FDA found human safety data only for the intranasal route, in a few dozen healthy adults and patients.

The full answer: what it is for, the dose, the units

What people take it for: People take it for focus, mental clarity and stress resilience. In Russia it is a registered drug used after stroke and for cognitive complaints, given as a nasal solution.

Does it work for focus, memory and stress resilience in healthy adults? D, no human evidence yet. Result: not tested in humans.

Grade D for focus in healthy adults: no trial we could verify measured cognitive performance in healthy people, and the one placebo-controlled study (24 adults) looked at a brain-imaging network. The strongest human data, small Russian stroke studies, sit at grade C.

No approval for any use.

Highest evidence for any use: C for recovery after ischemic stroke (small Russian studies).

Safety: C, thinly characterized. Small Russian studies report mild nasal irritation and headache, and FDA found human safety data only for the intranasal route, in a few dozen healthy adults and patients.

Do not use if: No formal contraindication list exists from a Western regulator.

Could it be placebo? No controlled trial measured focus or mood in healthy adults, so a placebo effect cannot be ruled out for those uses; the one placebo-controlled study measured brain imaging, not performance.

The dose people use, and the units to draw

Named human sources range from 0.25 mg once to 18 mg a day, nearly all intranasal and nearly all in patients rather than healthy adults. No named source gives a dose for focus.

Source	Dose	How often and how	Who it was for	Link
Gusev et al. 2018 (stroke rehabilitation study)	6000 mcg a day (6 mg)	2 courses of 10 days with a 20-day gap; route not stated in the abstract	110 adults after ischemic stroke (about 3 to 7 months after the stroke)	abstract, Material and methods
Gusev et al. 1997 (acute stroke, concurrent control group)	12 mg a day for moderate strokes, 18 mg a day for severe strokes	5-day course (moderate), 10-day course (severe); route not stated in the abstract	30 treated and 80 control patients in the acute period of hemispheric ischemic stroke	abstract, last sentence
Kaplan et al. 1996, as tabulated by FDA	1 mg (16 mcg per kg) daily, or 0.25 mg once	Intranasal; 1 mg daily for 2 days or a single 0.25 mg dose	19 healthy adult males	Table 3, Summary of References With Safety Information
Lebedeva et al. 2018, as tabulated by FDA	1.2 mgUse this dose	Intranasal 1% solution, single dose, resting fMRI at 5 and 20 minutes	24 healthy adults (14 received Semax, 10 placebo)	Table 3 (dose); PubMed abstract for design (PMID 30225715)
Koroleva et al. 1996, as tabulated by FDA	0.5 mg per kg	Intranasal, given once	37 adults with pain (trigeminal neuralgia, dental plexalgia, migraine)	Table 3, Summary of References With Safety Information

From 0.25 mg once intranasally in healthy men (Kaplan 1996, per FDA Table 3) to 18 mg a day in severe stroke (Gusev 1997), nearly all in patients.

Neither Huberman Lab episode searched (Apr 2024 with Huberman, Jun 2026 with Dr. Abud Bakri) mentions Semax, and Examine.com could not be opened (rate limited). No named source gives a dose for focus in healthy adults or any dose for the N-acetyl form. The site's earlier SubQ ranges had no named source. One abstract in FDA's table lists a daily figure that looks like a unit error and is not used.

Reported by the named source, never prescribed by us.

How many units do I draw?

On a U-100 insulin syringe, units = 100 x dose (mg) / (vial mg / water mL). Enter your vial size, the water you add and the dose in the calculator and it does the arithmetic. Open the dose calculator

Why it might work

Intranasal administration → partial CNS penetration
Semax is a synthetic heptapeptide base
Melanocortin receptor engagement (MC4R, MC5R) → downstream signaling
Semax shares structural homology with
BDNF and NGF upregulation → synaptic plasticity signaling
Multiple rodent studies report that Se
Dopamine and serotonin modulation → mood and attention effects
Rodent work shows Semax modulates dopa

Assumed pathway, not shown in people.

Assumed mechanism: Semax is a synthetic analog of the ACTH(4-10) melanocortin fragment (sequence Met-Glu-His-Phe-Pro-Gly-Pro), with the Pro-Gly-Pro tail added to resist enzymatic breakdown; the N-acetyl version adds an N-terminal acetyl group thought to block the first peptidase cleavage site. It is believed to act largely independent of steroidogenic ACTH activity, instead upregulating BDNF and NGF (via CREB signaling) and modulating dopaminergic and serotonergic tone, the presumed basis for neuroprotective and pro-focus effects. This is an assumed/theoretical mechanism derived mostly from animal and in-vitro data, not an FDA-approved indication.

The trials, claim by claim

Status

Semax is a registered pharmaceutical in Russia (approved 1994) for cerebrovascular and cognitive indications and appears on Russia's Essential Drugs List.

Russian regulatory approval and decades of clinical use, but that approval is not based on the multicenter RCT package Western regulators require, and confers no FDA equivalence.

PubMed 29798983: Efficacy of Semax at different stages of ischemic stroke, 110 patients (Zh Nevrol Psikhiatr 2018). Earlier controlled study: PMID 11517472 (1997)

Small human clinical studies (e.g., acute ischemic stroke cohorts from 1997 onward, and a 2018 functional-MRI study of the brain's Default Mode Network) report neurological/cognitive effects.

Result: worked

These are real human studies but small, largely Russian, and mostly open-label or mechanistic; the 2018 fMRI study provides a rare objective (imaging) human signal but is not an efficacy RCT.

PubMed 30225715: Effects of Semax on the Default Mode Network (Bull Exp Biol Med 2018, 24 healthy volunteers)

Semax upregulates BDNF/NGF and modulates dopaminergic and serotonergic systems.

Result: not tested in humans

This mechanism is established mainly in rodent and in-vitro work; it is the assumed basis for human cognitive claims, not proof of human cognitive benefit.

PubMed 17353092: Neurotrophin gene expression in rat brain under Semax (Neurosci Lett 2007)

Status

No FDA-approved Semax product exists in the US, and it is not on the 503A Bulks List; an advisory committee voted to recommend adding it, FDA has proposed no rule, and since October 28, 2026 an interim HHS enforcement-discretion policy covers compounding the nasal form under conditions (not a rule, not an approval).

Regulatory-status fact. Semax came off FDA bulk-compounding Category 2 in April 2026 when its nomination was withdrawn. On July 24, 2026 the Pharmacy Compounding Advisory Committee voted 8-5 to recommend it for the 503A Bulks List, against FDA staff's recommendation. The vote was 8-5 with one abstention. It is advisory; as of October 12, 2026 FDA had published no proposed rule. It is not a controlled substance but cannot be sold as a supplement.

FDA: July 23-24, 2026 PCAC meeting

The N-acetyl modification meaningfully improves stability/potency over plain Semax in humans.

Result: not tested in humans

Largely a vendor/theoretical claim. Acetylation plausibly blocks an N-terminal peptidase cleavage site, but there is little to no head-to-head human data distinguishing N-Acetyl Semax from Semax.

PubMed: N-Acetyl Semax

Status

FDA's July 2026 review found insufficient evidence that Semax works for cerebral ischemia, migraine or trigeminal neuralgia, and found human safety data only for the intranasal route.

Primary FDA briefing document, regulatory appraisal of the published record, not new trial data. Exposure counts: 33-47 healthy adults, 69 adults with conditions, 451 children.

FDA briefing document, Semax-related bulk drug substances, July 2026

Risks and the label warnings

Adverse events

Reported adverse effects are generally mild: nasal/mucosal irritation from intranasal use, transient headache, occasional fatigue, irritability, sleep or appetite changes, and minor short-lived heart-rate/blood-pressure fluctuations on initiation. Russian sources describe it as well tolerated, but these reports come from small studies without independent Western pharmacovigilance.

Contraindications

No formal contraindication list exists from a Western regulator. Reasonable caution applies to pregnancy/breastfeeding (no data), diabetes (possible glucose effect), uncontrolled hypertension/arrhythmia (autonomic effects on initiation), and concurrent serotonergic/dopaminergic psychiatric medication. Gray-market product purity, sterility, and dose accuracy are themselves a risk.

Theoretical concerns

As an ACTH/melanocortin fragment, theoretical concerns center on HPA-axis, glucose, and autonomic effects with chronic or supraphysiologic dosing, one source notes increased blood glucose in people with diabetes. FDA's July 2026 review also noted one report of possible anti-thrombotic activity, a bleeding question for people on blood thinners. Potent BDNF/dopamine modulation in a still-developing or psychiatric brain is incompletely characterized. The N-acetyl variant's pharmacology in humans is essentially uncharacterized.

What nobody knows yet

The biggest unknowns are long-term safety (no multi-year human data), reproductive/developmental safety, and whether N-Acetyl Semax behaves like plain Semax in humans. Source/purity variability across vendors means the actual molecule and dose in any given vial are uncertain. There is no Western RCT efficacy or safety package.

What else could explain the result

Most commonly run alongside Selank (the 'Russian stack'), and frequently with caffeine, modafinil, racetams, MK-677, or Cerebrolysin. Daytime focus claims are heavily confounded by these stimulants/nootropics, by sleep and workload changes, and by strong expectancy, making it very hard to attribute any subjective effect to Semax alone.

Is the vial what it says?

Verified against PubMed (Semax returns ~229 results, overwhelmingly rodent/in-vitro, with only a small minority of human studies, chiefly small Russian stroke cohorts from 1997-2018 and a 2018 fMRI study). Cross-checked regulatory status (non-FDA-approved, 503A compounding, PCAC review) and half-life across multiple sources. A circulating claim of a '120-patient placebo-controlled RCT' with specific NIHSS/mRS statistics could not be confirmed in the PubMed listing and is treated as unverified.

Half-life and storage

Half-life: Plasma half-life is very short, roughly 2-5 minutes for unmodified Semax, due to rapid degradation by peptidases (enkephalinase/carboxypeptidase). Proponents cite a 'paradox' of minutes-long plasma half-life but hours-to-24h CNS effects via intranasal nose-to-brain delivery; the prolonged-CNS-effect figures are largely extrapolated from labeled-tracer and rodent work and should be read as theoretical, not established human pharmacokinetics. Acetylation is claimed to extend half-life roughly 2-3x.

Once mixed: Supplied as a lyophilized powder; reconstituted with sterile bacteriostatic water or saline for intranasal use. Reported handling: refrigerate (2-8 C) after reconstitution, store upright, protect from light and heat, and use within about 2-4 weeks. Heat/room-temperature storage is said to degrade potency and risk microbial growth. Handling guidance is vendor/community-sourced, not from a regulated label.

What I noticed, and what people report

What people report

Volume of reports: moderate. A real body of reports, fairly consistent.

Moderate-to-high community volume: Semax is one of the more widely discussed nootropic peptides, with substantial Reddit/Substack/forum and vendor-blog coverage, heavily anchored to the Semax+Selank 'Russian stack.'

Fairly consistent themes, clearer thinking, calm/sustained focus without stimulant jitter or crash, and modest mood lift, but effects are described as subtle and variable, and a meaningful minority report little or nothing. Consistency is undercut by near-ubiquitous stacking.

Credibility is mixed and should be discounted: much of the online content is vendor- or affiliate-driven and recycles the same Russian-approval framing, and the genuine user reports are subjective and expectancy-prone. The most credible objective anchor is the small 2018 human fMRI study, not the marketing copy.

Many users describe 'lifted brain fog' and calm, sustained focus without the jitters or crash of caffeine/stimulants, though they consistently call the effect subtle rather than dramatic (anecdote, not proof).
It is most often discussed as half of the Semax+Selank 'Russian stack,' with Semax framed as the daytime focus/drive piece and Selank as the calming counterweight, which heavily confounds attribution.
A notable subset of users report minimal or no perceptible effect, and a few mention mild irritability, headache, or sleep changes, especially at higher or late-day doses.
Reported tolerability is generally good with no described crash or dependence, but these are unverified self-reports from forums and vendor-adjacent communities and should be discounted accordingly.

Reports are anecdote, not proof.

Can you tell if it is working?

Partly trackable

The only objective-ish readout is a structured, ideally blinded cognitive test battery, no wearable, scan, urine, or lab tracks semax efficacy.

Bloodwork

No blood proxy

Nothing on a routine panel confirms this one. Anyone who says otherwise is guessing.

Semax is an intranasal ACTH(4-10) analog whose action is confined to the CNS (melanocortin-receptor engagement plus BDNF/NGF and TrkB upregulation in hippocampus and cortex, with dopamine/serotonin modulation); it deliberately lacks ACTH's steroidogenic activity, so it moves no cortisol, ACTH, or other peripheral analyte that a routine panel measures.

Read this before you spend on labs

Routine bloodwork cannot confirm Semax is working. Its effects are cognitive and neuroprotective (focus, memory, stress resilience, stroke recovery) and are mediated centrally by BDNF/NGF and TrkB signaling. The proposed mediator, BDNF, is a research-only ELISA rather than a LabCorp/Quest orderable, and serum BDNF is a noisy, platelet-confounded proxy that poorly reflects brain BDNF, so even off-label it would not prove efficacy. Unlike its parent hormone, the ACTH(4-10) fragment does not stimulate the adrenal axis, so cortisol and ACTH will not track it either. Verify response with validated cognitive or symptom measures (a repeated attention/working-memory task or a target-symptom log), not blood. The only blood-relevant note is a theoretical rise in fasting glucose in diabetics, which is a safety signal, not evidence of benefit.

Dolotov OV et al., Brain Res 2006, Semax (ACTH 4-10 analog) regulates BDNF and trkB expression in rat hippocampus (rodent mechanism; central, not a peripheral blood marker)

Other ways to track it

OtherIndirect / noisy

Standardized cognitive test battery run n-of-1, e.g., psychomotor vigilance task (PVT) reaction time, an n-back working-memory task, or a validated attention/processing-speed app (Cambridge Brain Sciences, CANTAB-style tools)

A working result shows faster and steadier reaction times and better sustained-attention/accuracy scores on-drug versus off, beyond what practice alone explains, best isolated in a randomized, blinded (ideally placebo-controlled) design. A subtle or absent effect is a genuine, expected outcome: the human effect is described as subtle and variable, and a meaningful minority report nothing.

Semax's target effect is CNS attention/processing-speed and mental-fatigue reduction; cognitive performance is the only human-accessible objective readout of that effect. It is confounded by expectancy, practice, caffeine, modafinil/Selank co-use, and sleep, so it is a partial proxy rather than a clean biomarker.

Establish baseline across several sessions first to wash out practice/learning effects, then compare score distributions over time, not single sessions.

Bottom line

No physiological modality reflects semax in humans, not blood, urine, stool, sleep/HRV, CGM, VO2max, DEXA, or genetics. Its effect is subjective cognition, and the honest tracking tool is a validated cognitive test battery, not a scan or panel. Even that is only a partial proxy: it is heavily confounded by practice effects and expectancy (placebo risk is rated moderate and benefits are expectancy-sensitive), so it is only trustworthy inside a blinded, randomized design. Human evidence overall is weak, dated, and largely Russian open-label; the sole rigorous objective human signal (a 2018 resting-state fMRI Default Mode Network study, Lebedeva et al., n=14 semax vs 10 placebo, acute intranasal) is a small research tool, not a home tracker.

Logging baseline vs retest is the whole game. The Truth Tracker is our free log for bloodwork, DEXA, genetics, and wearable data, bring your own numbers.

How to track it

History

First documented human use: Human use dates to the early 1990s in Russia; Semax was approved by the Russian Ministry of Health in 1994 for cerebrovascular indications and added to Russia's Essential Drugs List. The earliest English-indexed human clinical reports appear around 1997 (acute ischemic stroke). No large multicenter randomized controlled trial meeting Western regulatory standards has been published, and no FDA-registered trial has been completed.

Update: an FDA advisory panel voted in favor of this one on July 23-24, 2026

The FDA's Pharmacy Compounding Advisory Committee voted to recommend adding this to the 503A Bulks List, meaning compounding pharmacies could legally prepare it. The vote: 8-5, with one abstention. Now read the fine print, because it matters more than the headline. The vote is advisory and changes nothing today: FDA still has to go through formal rulemaking, which can take a year, and it has overruled its own panels before. As of November 2, 2026, FDA has not published a proposed rule and this is not on the 503A Bulks List. Separately, HHS published a draft enforcement-discretion policy in the Federal Register on October 30 (docket HHS-OASH-2026-0496) that says HHS does not intend to act against pharmacies that compound certain single-ingredient peptides under conditions. The notice itself says compounded drugs are not FDA-approved. That is enforcement discretion: a draft, not a rule, not approval, and not a ruling that the compound works, and HHS can revise it. The list of named peptides and routes sits in an appendix we could not open, so which peptides it names is as press and law firms report it, not as we read it. FDA's own scientists recommended AGAINST adding it, citing thin human evidence and unassessed immunogenicity risk, and the committee voted the other way. That committee is also not neutral: it was reconstituted with recent appointees, and several work at or run clinics that sell peptide treatments. And none of this is a finding that the compound works. A compounding-eligibility vote is not drug approval, and it is not evidence. Our grade here is unchanged, because the evidence did not change.

Vote tallies as reported by the press (STAT, McDermott Will and Schulte); FDA has not posted tallies, minutes or a transcript, and its meeting materials are on its meeting page. Rechecked November 2, 2026 against FDA and Federal Register primary pages: FDA has published no proposed rule, docket FDA-2025-N-6895 closed July 22, 2026, and HHS published a draft enforcement-discretion policy in the Federal Register on October 30, 2026 (docket HHS-OASH-2026-0496). Nothing here is final, so check the current policy and rule before acting.. FDA, PCAC meeting, July 23-24 2026

1980sDeveloped at the Institute of Molecular Genetics, Russian Academy of Sciences, as an ACTH(4-10) analog stabilized with a Pro-Gly-Pro tail.
1994Approved by the Russian Ministry of Health for cerebrovascular indications; later added to Russia's Essential Drugs List.
1997Earliest English-indexed human clinical reports in acute ischemic stroke appear in the literature.
2005-2010Rodent studies establish dopaminergic/serotonergic activation and BDNF/NGF transcriptional upregulation as the assumed mechanism.
2018Human fMRI study reports Semax effects on the brain's Default Mode Network, a rare objective human data point.
2026In the US, withdrawn from FDA bulk-compounding Category 2 (April), then recommended 8-5 for the 503A Bulks List by the FDA's Pharmacy Compounding Advisory Committee on July 24, 2026. Advisory only: no proposed rule has followed, so it remains non-FDA-approved and off the Bulks List; on October 28, 2026 an interim HHS enforcement-discretion policy began covering compounding the nasal form under conditions (not a rule, not an approval).

All sources

PubMed. Semax (all indexed studies)(~229 results, overwhelmingly rodent/in-vitro; human studies are a small minority. Use to gauge the true human-evidence depth.)
PubMed. Semax ischemic stroke (human clinical reports)(Includes the small Russian human stroke studies (1997, 1999, 2018), the core human clinical evidence.)
PubMed. Semax BDNF / neurotrophin (mechanism)(Mostly rodent/in-vitro mechanistic work behind the assumed BDNF/NGF upregulation claim.)
PubMed. N-Acetyl Semax(Sparse, illustrates how little the specific N-acetyl variant has been independently studied.)
ClinicalTrials.gov. Semax registered trials(Check for any registered/Western trials; relevant to FDA/PCAC compounding-review status.)
FDA briefing document, Semax-related bulk drug substances, July 2026(Primary FDA review: insufficient evidence for cerebral ischemia, migraine and trigeminal neuralgia; exposure counts; one report of possible anti-thrombotic activity.)
Gusev EI, Martynov MY, Kostenko EV, Petrova LV, Bobyreva SN. Zh Nevrol Psikhiatr Im S S Korsakova 2018;118(3 Pt 2):61-68 (PMID 29798983)(dose table)
Gusev EI, Skvortsova VI, Miasoedov NF et al. Zh Nevrol Psikhiatr Im S S Korsakova 1997;97(6):26-34 (PMID 11517472)(dose table)
FDA briefing document, Semax-related bulk drug substances, PCAC July 23-24, 2026, Table 3 (Kaplan et al. 1996)(dose table)
Lebedeva IS et al. Bull Exp Biol Med 2018 (PMID 30225715); dose from FDA briefing document Table 3(dose table)
FDA briefing document, Semax-related bulk drug substances, PCAC July 23-24, 2026, Table 3 (Koroleva et al. 1996)(dose table)

Not medical advice. Grades reflect the evidence as of the date above and will change as data arrives. Reports from users are anecdote, not proof. Talk to a licensed clinician before you act on anything here.