Peptides for Brain Fog and Focus: What Is Prescribed, and What Works

Brain fog is a description, not a diagnosis. The word covers slow recall, losing the thread mid-sentence, reading a paragraph three times, and the sense that thinking costs more effort than it used to. Several ordinary medical causes produce exactly that, and none of them are improved by a peptide.

A physician reviewing your intake looks at this list before anything else. If the answer is on it, the answer is on it. Bloodwork before peptides covers what is usually checked.

Sustained attention, task switching and holding several things in mind at once run on the prefrontal cortex, and that region is the first to degrade when arousal is wrong. Too little arousal, from short sleep or a sedating drug, and the system is sluggish; too much, from stress hormones or stimulants, and it becomes distractible. Dopamine and noradrenaline signalling in that circuit follow an inverted U: a middle band is where focus lives. Most of what people call "slow, effortful thinking" is that circuit running outside its band, which is why sleep, caffeine timing and stress explain more cases than any molecule does. It is also why Semax, which animal research describes as acting on dopaminergic and serotonergic systems, is the peptide reached for on this side of the complaint.

Working memory is small. Somewhere between four and seven items, and a running background process of worry takes up several of them permanently. That is the mechanism behind the "fast, loud and unproductive" kind of fog: thinking is not slow, it is crowded. People describe rereading, forgetting why they walked into a room, and being unable to finish a thought, and they are often surprised when a physician calls it anxiety, because they do not feel afraid. This is the version where a calming agent that does not sedate is the logical tool, and it is the rationale for Selank, whose human studies are in anxiety disorders.

A large share of people who say "brain fog" mean "I run out of capacity by 2pm," which is an energy complaint wearing a cognitive label. The brain uses about a fifth of resting energy expenditure and is unusually sensitive to how well mitochondria supply it. Iron deficiency, thyroid disease, poor sleep and metabolic disease all present this way. So does ordinary deconditioning. This is the version where NAD+ and MOTS-c enter the conversation, and it is also the version most likely to have a blood-test answer, which is why the physician's first step is the panel, not the vial. Peptides for energy and fatigue covers that overlap in depth.

A synthetic heptapeptide related to a fragment of ACTH, adrenocorticotropic hormone, without the hormonal activity of the parent molecule. It was developed in Russia and is registered there as a nasal drug for neurological indications. Animal research describes it regulating brain-derived neurotrophic factor and its receptor trkB in the rat hippocampus (Brain Research, 2006), activating dopaminergic and serotonergic brain systems in rodents (Neurochemical Research, 2005), and changing the expression of immune and vascular genes after experimental stroke (BMC Genomics, 2014). A 2024 paper in the European Journal of Pharmacology reported antidepressant-like and anti-stress effects in male rats under chronic unpredictable stress.

The human work is Russian and clinical, in stroke and cerebrovascular disease rather than in focus; it is set out in the evidence section below. Semax is the one used when the complaint is attention and mental effort rather than mood. The reviewed directions on the Semax page are to inject 0.25 mL (25 units) subcutaneously once daily Monday through Friday. More detail is in what is Semax.

A synthetic heptapeptide related to a fragment of tuftsin, an immunomodulatory peptide, with a Pro-Gly-Pro tail added for stability. Russian research describes it affecting the expression of genes involved in GABAergic neurotransmission in cultured neuroblastoma cells (Frontiers in Pharmacology, 2016 and 2017), inhibiting the enzymes that degrade enkephalins (Bulletin of Experimental Biology and Medicine, 2001), regulating BDNF expression in the rat hippocampus after intranasal administration (Doklady Biological Sciences, 2008), and protecting against memory impairment during alcohol withdrawal in rats by regulating BDNF in the hippocampus and prefrontal cortex (Bulletin of Experimental Biology and Medicine, 2019).

The human work is where Selank stands apart from most peptides on this site: three small Russian comparator trials in anxiety disorders, described below, one of which measured attention and memory directly. The distinction matters when choosing. If your thinking is slow, Semax is the usual choice. If your thinking is fast, loud and unproductive, Selank is. Many prescriptions include both because most people describe some of each. The reviewed directions on the Selank page match Semax: 0.25 mL (25 units) subcutaneously once daily Monday through Friday. See what is Selank.

Semax + Selank is the two molecules compounded together, for the common case where someone describes both effortful thinking and a crowded, anxious mind. There is no trial of the combination; the rationale is that the two act through different described mechanisms, monoamine and neurotrophin signalling on one side, GABAergic and enkephalin systems on the other, and that prescribers have used them together for years. One vial, one injection, the same Monday-through-Friday rhythm. Whether the combination or a single agent is the right starting point is your physician's call.

SYNAPSE is built for the version of fog that comes with low energy and poor recovery. It adds two compounds to the Semax and Selank pair.

MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA rather than in the cell nucleus. Research in mice describes it acting on metabolic regulation through AMPK signalling, preventing diet-induced insulin resistance (Cell Metabolism, 2015), translocating to the nucleus to regulate gene expression under metabolic stress (Cell Metabolism, 2018), and, when given to mice across the lifespan, being associated with better physical capacity (Nature Communications, 2021), where the authors also reported that exercise raises the body's own MOTS-c in human muscle and blood. There are no randomized controlled trials of MOTS-c in humans.

Tesamorelin is a stabilized analog of growth hormone-releasing hormone and the one component here with a Western randomized trial on cognition, the 2012 Archives of Neurology trial described below. It raises IGF-1, which is why bloodwork is commonly required before SYNAPSE is prescribed: a physician wants a baseline.

SYNAPSE suits the person whose fog is inseparable from a flat afternoon and slow recovery from exertion, once the blood-test causes of that pattern have been excluded. The reviewed directions are 0.25 mL (25 units) subcutaneously once daily Monday through Friday.

ELEVATE is the pairing for fog that travels with gut or inflammatory complaints. The rationale is the research linking gut and systemic inflammation to fatigue and cognitive symptoms through cytokine signalling; inflammatory illness reliably produces fog, though nobody has shown that treating low-grade gut inflammation clears it in otherwise healthy adults. BPC-157 is a fifteen-amino-acid fragment of a gastric protein with a large animal literature on protection of the gut lining (Current Pharmaceutical Design, 2011); KPV is the three-amino-acid tail of alpha-MSH, described in mouse colitis models as reducing intestinal inflammation through PepT1-mediated uptake (Gastroenterology, 2008; Inflammatory Bowel Disease, 2008), and in a 2013 PLoS One study as reducing inflammation and cell loss after experimental brain injury in mice. Neither has a randomized human trial for any indication, and there is no human study of either for cognition. The blend exists because prescribers see the gut-and-fog pattern often and the cognitive pair alone does not address the gut side. Directions match the other injectables: 0.25 mL (25 units) subcutaneously once daily Monday through Friday.

Not a peptide. Nicotinamide adenine dinucleotide is a coenzyme present in every cell that carries electrons through the reactions converting nutrients into usable energy, and is consumed as a substrate by sirtuins and PARP enzymes. Levels are reported to decline with age in human tissue (PLOS ONE, 2012). It is prescribed for the tired version of fog, and the honest evidence summary is that almost all human trial data concerns oral precursors, NMN and NR, rather than NAD+ itself: those trials reliably raise blood NAD+ and produce small, mixed functional effects, with the clearest signals in older or metabolically impaired adults (Nature Communications, 2018; Science, 2021; GeroScience, 2023). The NADPARK study (Cell Metabolism, 2022) reported that oral NR raised brain NAD levels in 30 newly diagnosed Parkinson's patients. For NAD+ given directly there is a 2019 intravenous pilot that measured the molecule in blood and urine and tested no clinical outcome. There are no randomized controlled trials of subcutaneous NAD+ injection for cognition, fatigue or anything else. The reviewed directions on the NAD+ page are 0.83 mL (83 units) subcutaneously three times per week. A needle-free NAD+ nasal spray also exists. Marketing claims around NAD+ regularly exceed the human outcome data, and an honest prescriber says so.

Two that appear in the category but sit further out. Dihexa is a small peptide derivative developed from angiotensin IV, described as a potentiator of the hepatocyte growth factor and c-Met system, with rodent work reporting better performance in spatial memory tasks in scopolamine-impaired and aged rats (Journal of Pharmacology and Experimental Therapeutics, 2013 and 2014) and in a mouse model of Alzheimer's-type pathology (Brain Sciences, 2021). That growth-factor mechanism is also the reason for caution, particularly with any personal history of cancer. PE-22-28 is a shortened analog of spadin, a fragment of the sortilin propeptide, described as blocking the TREK-1 potassium channel, a mechanism associated in rodent research with rapid antidepressant-like effects (PLoS Biology, 2010; Frontiers in Pharmacology, 2017). Both are preclinical only: there are no randomized controlled trials, no open-label trials and no published case series of either in humans. Neither substitutes for established treatment of depression, and a physician will usually want the better-characterized options exhausted first.

Worth saying plainly, because it is the use most people reading this page have in mind. There is no randomized, placebo-controlled trial of Semax, Selank, MOTS-c, NAD+ injection, Dihexa or PE-22-28 for attention, memory or productivity in healthy adults. The FDA's July 2026 briefing document on Semax records that it was nominated for "ADHD" and "nootropic" use among others, that ADHD "was not evaluated because supporting literature for this use was not found," and that "nootropic" has no diagnosis code and was folded into the evaluation for cerebral ischemia.

For Semax, a 1997 controlled study in the Korsakov Journal of Neurology and Psychiatry compared 30 patients in the acute phase of ischemic stroke given intranasal Semax alongside standard care with 80 conventionally treated patients, reporting faster regression of deficits; a 2018 study from the same group followed 110 post-stroke patients and reported higher plasma BDNF and better independence scores in those who received it. A 2005 evaluation in 187 patients with chronic cerebrovascular insufficiency reported clinical improvement and good tolerability. In healthy adults the published work is mechanistic: a 2018 paper in the Bulletin of Experimental Biology and Medicine gave 14 healthy volunteers a single intranasal dose and measured changes in the brain's default mode network on functional MRI. A 2007 paper in Medical Hypotheses proposed Semax as a candidate for attention-deficit hyperactivity disorder; it is a hypothesis paper, not a trial. Nearly all of this used the intranasal product registered in Russia.

For Selank, a 2008 study in the Korsakov Journal compared Selank with the benzodiazepine medazepam in 62 patients with generalized anxiety disorder or neurasthenia and reported similar anxiolytic effects, with Selank additionally described as anti-asthenic and mildly activating. A 2014 comparison against phenazepam in 60 patients with anxiety-phobic and somatoform disorders reported a pronounced anxiolytic effect and a "mild nootropic" effect. A 2015 study in 70 patients added Selank to phenazepam and reported that the combination reduced the benzodiazepine's effects on attention and memory, measured on Stroop and verbal-fluency tests. Those are small, active-comparator trials, published in Russian, not described as blinded, and never replicated outside Russia; a 2021 review in the Journal of Clinical Pharmacology characterized Selank as poorly studied beyond its country of origin. They are still the closest thing this category has to controlled human data on attention. That is a weaker position than it sounds when quoted, and a stronger one than "there is no evidence."

The 2012 Archives of Neurology trial of tesamorelin is the single best piece of human cognitive evidence in this category. It randomized 152 adults aged 55 to 87, 66 of them with mild cognitive impairment, to 20 weeks of daily subcutaneous tesamorelin or placebo, and reported a favorable effect on a cognitive composite, strongest for executive function, comparable in the healthy and MCI groups, with IGF-1 rising within the physiological range. A 2013 follow-up in JAMA Neurology reported higher brain GABA levels on spectroscopy in the treated group. Three cautions. The participants were older adults. The trial used tesamorelin alone at its own dose, not SYNAPSE. And it has not been replicated in a younger population with subjective fog.

MOTS-c, by contrast, has a coherent mouse literature, human observational data on the body's own peptide, and no human treatment trial. NAD+ has good human data for oral precursors raising blood NAD+, mixed data on whether that changes how people function, and no controlled trial of the injected form. Neither has a cognition endpoint in humans.

• It does not establish an effect on focus, memory or attention in healthy adults for any of these compounds. No trial has measured that.
• It does not establish an effect size or a timeline. Anything about "results in two weeks" is prescriber experience or extrapolation.
• It does not establish equivalence between the intranasal route of the Russian studies and subcutaneous injection.
• It does not establish anything about combinations. The blends have no trials of their own.
• It does not establish long-term safety over years of continuous use.
• It does not establish efficacy for any condition as an FDA-approved treatment. None of these is approved for anything in the United States.

Every product on this page is compounded by a state-licensed pharmacy to a physician's prescription. The FDA's own compounding Q&A states: "Compounded drugs are not FDA-approved. This means that FDA does not verify the safety, effectiveness or quality of compounded drugs before they are marketed." Under section 503A a pharmacy may compound with a bulk substance if it has a USP or NF monograph, is a component of an FDA-approved drug, or appears on the FDA's 503A bulks list. For nominated substances not yet decided the FDA runs an interim policy with three categories: Category 1 under evaluation, Category 2 flagged for significant safety risks, Category 3 nominated without adequate support; the agency has also said it "does not intend to place bulk drug substances nominated on or after January 7, 2025, into these categories." The positive list at 21 CFR 216.23 still holds six substances, none a peptide and none on this page.

On 15 April 2026 the FDA announced the removal of twelve peptides from Category 2, effective about a week later, because their nominations had been withdrawn by the nominators, and was explicit that removal from Category 2 "does not, by itself, place these substances on the 503A bulks list or into Category 1." The FDA's safety-risks page, current as of 22 April 2026, now lists Semax, Selank acetate (TP-7), MOTS-c, Dihexa acetate, BPC-157 and KPV under bulk drug substances "nominated but withdrawn," and none of them in the active Category 2 table. The categories document updated 14 May 2026 carries none of them in Category 1, 2 or 3.

The FDA brought Semax, as the free base and the acetate, to its Pharmacy Compounding Advisory Committee on 24 July 2026, for the nominated uses of cerebral ischemia, migraine and trigeminal neuralgia. The FDA's briefing document concluded that "a balancing of the criteria weighs against" listing: it could not rule out immunogenicity from peptide-related impurities, found "insufficient evidence to support the effectiveness" for the nominated uses on the English-language material available, and noted that Semax products are "widely marketed in the United States" for anxiety, depression and attention among other things. The committee voted 8 to 5, with one abstention, to recommend adding Semax to the 503A Bulks List, one of six peptides it recommended that week against the advice of FDA's own scientists. A committee vote is advice, not a decision. The FDA issues its own determination afterwards, and as of September 2026 it has not.

Selank acetate was placed in Category 2 in 2023 and its nomination was later withdrawn; the FDA's safety-risks page lists it among substances nominated but withdrawn, it appears in no category on the 14 May 2026 list, it was not on the July 2026 agenda, and it is not among the five substances scheduled for the committee's next session. Not flagged as a safety risk, never evaluated by the committee, no active nomination.

The committee reviewed MOTS-c, BPC-157, KPV and TB-500 on 23 July 2026. It voted 7 to 5 with two abstentions to recommend MOTS-c, and 8 to 6 with one abstention each to recommend BPC-157 and KPV, in every case against FDA staff, who "recommended against inclusion of the peptides, citing concerns of insufficient safety, efficacy, and moiety characterization information." That covers the non-cognitive components of SYNAPSE and ELEVATE. The FDA's determinations are pending.

NAD+ has a different history and was never part of the 2026 peptide changes. Nicotinamide adenine dinucleotide, its reduced form NADH and methylcobalamin all sit in Category 1, substances under evaluation, in the FDA's categories document updated 14 May 2026; one specific salt, beta-nicotinamide adenine dinucleotide disodium salt trihydrate, was nominated separately and sits in Category 3. Under the interim policy the FDA does not intend to act against a compounder using a Category 1 substance while evaluation is pending, provided the guidance's conditions are met.

Dihexa acetate is off Category 2 and listed as nominated but withdrawn, and the FDA has announced it will convene the advisory committee before the end of February 2027 to consider it for the bulks list, alongside cathelicidin (LL-37), GHK-Cu, Melanotan II and PEG-MGF.

PE-22-28 does not appear in Category 1, 2 or 3 of the 14 May 2026 document, is not named on the safety-risks page either in the Category 2 table or among withdrawn substances, and was not on the July 2026 agenda. No safety notice, no vote either way; it has simply not been through the process.

Tesamorelin's position is different and did not move in 2026. Egrifta (tesamorelin acetate), application 022505, was approved on 10 November 2010. The current formulation, Egrifta WR, carries a label revised March 2025 with a single indication, "the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy," dosed at 1.28 mg once daily, with limitations of use including that long-term cardiovascular safety has not been established and that it "is not indicated for weight loss management as it has a weight neutral effect." Compounded tesamorelin is not Egrifta: it is prepared to a prescription, has not been reviewed by the FDA as a finished product, and its use in SYNAPSE is off-label, a physician's decision and common across medicine, but it should be understood as such.

The 2026 WADA Prohibited List, in effect from 1 January 2026, does not name Semax, Selank, Dihexa, PE-22-28 or NAD+. It names BPC-157 in section S0, non-approved substances, prohibited at all times, which covers ELEVATE; it lists tesamorelin under S2.2.4, growth hormone releasing factors, and MOTS-c under S4.4.1, activators of AMP-activated protein kinase, both prohibited at all times, which covers SYNAPSE. Semax's parent hormone class, corticotrophins, appears at S2.2.2, and a tested athlete should ask their anti-doping body about an ACTH fragment before assuming anything.

None of this changes the basic position: each of these is legal for a licensed physician to prescribe and a state-licensed pharmacy to compound, and none is an FDA-approved drug product.

Short sleep, fragmented sleep and untreated sleep apnea produce fog directly and reliably. A physician asks about duration, snoring, witnessed pauses and whether the fog is worst in the morning. If the night is the problem, no peptide on this page fixes it and peptides for sleep is the better page. Alcohol, cannabis, antihistamines, sleep aids, some blood-pressure drugs, opioids and benzodiazepines all produce fog with a daily pattern, and caffeine after early afternoon produces the sleep problem above. This is why the intake asks for everything you take, including over-the-counter.

Thyroid function, ferritin and B12. An underactive thyroid slows thinking; a ferritin at the floor of the normal range is the classic result that is technically normal and practically the answer; B12 deficiency produces fog with tingling and balance changes and is common on metformin, acid suppressants and vegetarian diets. At-home blood testing covers thyroid, metabolic and hormone markers without a lab visit. If the answer is on the panel, the treatment is the deficiency, and for B12 specifically Pepti prescribes methylcobalamin rather than a nootropic peptide.

Depression presents as fog with loss of interest; an anxiety disorder as fog with constant background worry. Both have established treatments with real trial evidence. If you are already under psychiatric care, the physician needs to know, because Selank and PE-22-28 touch the same systems as your existing medication.

New confusion, word-finding failure, personality change, fog that is progressive month to month, or fog after a head injury. Those need a neurological assessment, and a peptide would only delay it.

If the night is short or fragmented, the night is the treatment. Where the issue is falling and staying asleep rather than apnea, DSIP or the SERENITY blend, which pairs DSIP with Selank, belong to that conversation; Semax in the evening belongs to nobody's.

A low ferritin, a low B12 or an abnormal thyroid result is an answer, and the treatment is the deficiency. Methylcobalamin is the B12 product Pepti prescribes; iron and thyroid are treated conventionally by your physician.

Where the flat afternoon arrives with weight gain or a rising HbA1c, the metabolic problem is upstream. MOTS-c is aimed at that biology, but the compounds with large randomized trials for weight and glucose are semaglutide and tirzepatide, and a physician will usually want that conversation first. Peptides for energy and fatigue covers the fatigue-first route.

If a physician hears a mood disorder rather than a focus complaint, the established treatments come first; Selank may still have a place alongside them, coordinated with whoever prescribes the rest. And if you have not had thyroid, ferritin and B12 checked, the assessment and a blood panel come before any of the products above. A consultation does not guarantee a prescription, and being declined is refunded.