Selank vs Dihexa: Calm vs Recall, Evidence, FDA Status, Dosing and Cost

Every figure is an all-in monthly price covering the medication, physician review, refill management and shipping. There is no separate membership fee, and Pepti is cash-pay and does not bill insurance. Current pricing always lives on each product page.

Calm versus recall

People sometimes ask which is the "stronger nootropic." The question does not fit. Selank is described as taking the edge off: lowering anxiety and stress reactivity so that concentration is easier. Its "mild nootropic" effect in the Russian trials was measured on attention and verbal-fluency tests in anxious patients. Dihexa is described as acting on memory formation itself, but only in rodents. No study has measured both, and neither has been tested for cognition in healthy adults.

The evidence gap is large

Selank's evidence has real limits: small trials, no placebo, one country, the nasal route. But it is human evidence on validated anxiety scales, compared against established drugs, with a formal side-effect scale. Dihexa has an interesting animal story, fewer independent labs, a retracted mechanism and nothing in people. That gap matters more than any difference in mechanism.

Both went into Category 2 in 2023 and both are out of it now, by different routes. As of the FDA pages checked in September 2026:

Neither is banned. Both remain legal to prescribe and dispense as compounded medications. Compounded medications are not FDA approved, and neither is an FDA-approved drug. See are peptides FDA approved.

Both are injected under the skin into the abdomen or thigh, rotating sites, once a day on weekdays with weekends off. Both vials are multi-dose solutions shipped ready to use, refrigerated with ice packs, with sterile syringes and alcohol prep pads.

The draw is identical, but because the vials differ in strength, the same 25 units delivers twice as much Selank as Dihexa. On a U-100 insulin syringe, 1 unit is 0.01 mL; the milligram figures are arithmetic for reading a label, not a way to set a dose. Your physician sets your directions after reviewing your intake, and your directions are printed on the vial. Refills run every 28 days, one vial per fill. More is in Selank dosage.

Selank. The Russian trials, which used a formal side-effect scale, reported no sedation, memory impairment, dependence or withdrawal over the study periods. With the injection, what gets reported is mostly injection-site redness, mild soreness and occasional bruising. Some people describe early fatigue or a flat feeling, and a few describe feeling wired; both are usually described as settling. Selank has not been studied alongside SSRIs, SNRIs, stimulants or antipsychotics. More is in Selank side effects.

Dihexa. There is no human safety data. Prescribers report injection-site redness or soreness, headache, trouble sleeping if dosed late, and a restless or over-alert feeling in the first days. The bigger question is theoretical: its proposed mechanism runs through HGF/c-Met, a growth pathway over-active in many cancers. Nothing has shown Dihexa causes or speeds a tumor, and nothing rules it out. More is in Dihexa side effects.

For both, message your care team about anything unexpected, and about any marked change in mood. Facial or throat swelling, a widespread rash or difficulty breathing is an emergency: call 911 first, then tell your physician.

Neither peptide has a Western-standard, placebo-controlled trial for cognition or anxiety. Selank has small Russian comparator trials in anxiety disorders that reported effects similar to benzodiazepines without their sedation, by the nasal route, from the developing institutions. Dihexa has rodent studies, a retracted mechanism, one supportive independent mouse study and no human data. Any provider claiming either has been shown to sharpen thinking in healthy people is overstating it. What would change the picture is a randomized, placebo-controlled trial of either by injection; none has been published.

Neither can be bought legitimately without a prescription. Sites selling them "for research use only" are not accountable for what is in the vial: identity, purity, sterility and concentration are untested. The prescription route:

1. Complete a free online intake covering your history, medications and what you want help with.
2. A physician licensed in your state reviews it, usually within 24 hours.
3. If it is appropriate, a PCAB-accredited, FDA-registered US 503A compounding pharmacy prepares it to that prescription. Lot test results are published at /quality/lab-results.
4. It ships refrigerated with ice packs and your directions printed on the vial.
5. Your physician stays reachable for questions and dose changes.

Pepti prescribes both in every state except Oklahoma, plus DC Step by step: how to get Selank prescribed online and how to get Dihexa prescribed online.