Injection-site soreness · transient flu-like feeling or low mood for a few days · cost
Typical use
1.5-1.6 mg subQ twice weekly (matches Zadaxin label), often in courses during cold season or when exposed. Users report 420–710 mcg/day (median 500 mcg, n=11).
Stacked with
Stacked with
Thymosin beta-4 / TB-500: Doctors prescribe the pair for long COVID, and one ME/CFS user said Tβ4 calmed their Ta1 flare. · KPV: Pitched for long COVID, MCAS and CIRS: Ta1 to rebalance immunity, KPV to damp the inflammation. · SS-31 / MOTS-c: Long-COVID users follow an immune course of Ta1 with mitochondrial peptides for energy.
Safety
Watch
Theoretical: immune stimulation could flare autoimmune disease (a few anecdotal flares in ME/CFS); contraindicated with transplant immunosuppression · Generic: grey-market endotoxin (LPS) contamination; FDA flagged immunogenicity/impurity concerns for compounded Ta1
Tier by safety barStrict CautionBalanced CautionEvidence only Caution
Seen harm1 of 3
Mechanism2 of 3
Data gap1 of 3
Silent harm1 of 3
Product3 of 3
Never if
Transplant or other deliberate immunosuppression (label) · Active autoimmune disease · Pregnancy (label)
Two different crowds. Healthy parents, travellers and autoimmune users are almost uniformly positive: fewer or shorter colds while the household gets sick, falling thyroid antibodies or B cells, a few striking remissions (lupus/Sjögren's, lichen sclerosus). In long COVID, ME/CFS, MCAS and CIRS it splits roughly in half: some get energy back, but many get a flu-like immune flare or PEM crash within a day of the first dose, usually gone in days but occasionally lasting weeks to months, even at 100 mcg. Those who persist mostly titrate up from 100-300 mcg. Outright 'felt nothing' reports are only about 1 in 10.
I am also mild from Covid, and have been taking high dose TA1 for unrelated reasons, 3mg every 3 days, for about 2 months now. Zero change in symptoms.
NothingEnergy · 3 mg every 3 days · Injection · about 2 months
Approved abroad as Zadaxin but not in the US; FDA Category 2 and left out of the Oct 2026 HHS compounding carve-out.
A month at 210–230 mcg/day costs ≈ €38–40 from Semax Polska at €5.87/mg. At the 420–710 mcg/day users report, ≈ €74–130.
Cheapest from trusted shops in the EU
Shop
Pack
Price
Per mg
Per month
Testing
Semax PolskaEU · PLTrust 4/5Each product shows an Analiza Białek (Wrocław) HPLC report naming its operator Dobre Peptydy sp. z o.o. as the client, with a verification password (Semax 60 mg: 62.18 mg, 99%), and Reddit buyers since 2024 report fast, professional deliveries; the only complaints are about felt effect.Ships to France for €14, 1–5 days.COAs ↗
powder · 5 mg
€29
€5.87/mg
≈ €38–40 a month
Third-party tested
Studies
Evidence
Approved drug in ~35 countries (Zadaxin, hepatitis B/C, vaccine adjuvant); large human RCT (TESTS, 1,106 sepsis patients, BMJ 2025) found no mortality benefit and safety similar to placebo
The peptide's chain of amino acids from its start (the N-terminus) to its end, one bead and one letter for each: A alanine, C cysteine, D aspartic acid, E glutamic acid, F phenylalanine, G glycine, H histidine, I isoleucine, K lysine, L leucine, M methionine, N asparagine, P proline, Q glutamine, R arginine, S serine, T threonine, V valine, W tryptophan, Y tyrosine. A modification such as an N-acetyl cap or a C-terminal amide changes how long it lasts in the body. Length tells related peptides apart, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4, and predicts neither effect nor safety.
Report grades
Every first-hand Reddit or X report is graded on its own, from glowing through positive, mixed, nothing and negative to bad reaction, and the bar shows how those grades split. Posts that look vendor-adjacent stay on the peptide's page but are left out of the counts.
GlowingPositiveMixedNothingNegativeBad reaction
% positive
The share of a peptide's graded Reddit and X reports that are glowing or positive, vendor-adjacent posts left out. A peptide with few reports is pulled toward the average of all reports, as if it had eight average ones besides its own, so two glowing posts cannot top the list. Peptides rank by this figure, those with no graded report yet after those with one, and Avoid ones after every other entry.
Researcher estimate
No first-hand report of this peptide has been graded yet, so the figure is the researchers' own rating out of 10 from what they read about it. It ranks after every peptide with graded reports until its own arrive.
Safety tier
Each peptide is tiered Clean, Caution or Avoid from its five risk axes under the chosen safety bar. An Avoid peptide carries a real risk of harm, a plausible route to serious harm rather than mere unpleasantness, so it stays listed with the reason but ranks behind every other entry, however good its reviews.
Safety bar
The safety bar sets how much risk it takes to rate a peptide Avoid. Strict: out on any serious mechanism with little human data, or any documented serious harm. Balanced: out on documented serious harm (unless it is obvious, reversible and from a regulated product), or a serious mechanism whose harm would be silent with no human data at all. Evidence only: out only on documented serious harm in humans that is lasting, delayed or from grey-market product.
Seen harm
Documented serious adverse events in humans, from 0 for none despite real exposure to 3 for deaths or several well-documented serious harms. Serious means a hospital or emergency visit or harm lasting weeks, so a headache or a bad night does not count.
Mechanism
A plausible biological route to serious harm at the doses people use, such as growth-factor signalling, hormone-axis suppression, heart or blood-pressure effects or immune activation. It runs from 0 when none is known to 3 when a dangerous pathway has been shown in living animals.
Data gap
How little human safety data exists for the molecule actually sold, from 0 for an approved drug with large trials and years of use to 3 for no human safety data at all. A modified analogue does not inherit its parent's trials.
Silent harm
Whether the feared harm would show quickly or stay hidden, from 0 when it is obvious and goes on stopping to 3 when it is silent and delayed, like tumour promotion or slow organ damage. User reports cannot reveal a harm that takes years to appear, so a high score here limits what good reviews can tell you.
Product
The risk of what people actually buy, from 0 for a regulated pharmacy or supplement product taken by mouth or on the skin to 3 for a grey-market injectable. In one dataset of 6,441 grey-market samples, 42–71% failed basic quality criteria and 15% carried endotoxin; taken by mouth or in the nose, a pack avoids the injection risks.
Evidence
The strongest kind of study behind the peptide's effects, from an approved drug through human controlled trials and small human studies to animal work or nothing of its own. Animal results often fail to carry over to people.
Access
How people get it: as an approved drug, a compounded prescription, an over-the-counter supplement or from the grey market, where nobody checks the vial. The channel decides both the legal position and the risk of a bad batch.
Price per month
Thirty days of the typical dose, from its low end to its high end, priced at the listing a careful buyer would choose: in stock, from a shop scoring 4 of 5 on trust (third-party tested where no score is set), failing that 3, a pure pack before a blend, a European shop first, then the cheapest per mg. The range is the dose's, not the shops'. A per-dose amount counts once a day unless the dose says otherwise. Prices are in euros at ECB rates of 2026-10-29, before shipping; the shop table keeps each listing's price per mg, per gram for bulk supplements. Where no listing can be priced the researchers' own estimate stands in, and says so.
Dose users report
The middle half of the daily doses stated in at least five first-hand reports, vendor posts left out. Where its middle sits more than twice above or below the declared dose, the month is priced at it as well, since what people take is what they pay for.
Shop trust
Each shop's trust on a 1–5 scale, read from its testing and its reputation: 1 for serious red flags (fabricated COAs, scam reports, impersonation, a closed shop), 2 for no public testing, a new shop or active complaints such as seized parcels, 3 for its own COAs or a short track record, 4 for verified third-party testing or a strong reputation, and 5 for third-party batch reports that name the shop, with years of good independent reputation. A shop without a score counts third-party batch testing as 4, its own COAs as 3 and no public tests as 2.
Best value
Within a category or a goal, a peptide that no other beats on both counts: none is rated more positively for the same or a lower monthly price, and none costs less for the same or a higher rating. The chart joins these into the best-value line; the cheapest of them and the best-rated of them both make it, so the line spans the trade-off from cheap to best. Avoid entries never count, and a peptide needs both a % positive and a price to be compared.
Testing
Whether the shop publishes lab results: third-party tested means an independent lab checks each batch, own COA means the shop's own certificate of analysis, and no public tests means neither. A certificate shows purity, not safety.
Added peptide
Some packs sold under one peptide's name hold a second one, such as 5 mg GHK-Cu in a nasal kit, stated only in the description. Sprayed in the nose or injected it reaches the blood like an injection, so it carries the risk of that route and is tiered as the injectable form, whatever its tier on the skin. A pack whose page gives no contents list may hold more than its name.