PepRank

Thymalin

55%positive12 reports

Also: thymus polypeptide complex · Timalin

CautionLongevitySleepInjection

Russian thymus-extract bioregulator for immune 'renewal' in older people; thin evidence.

mixture: calf thymus polypeptide extract; EW (Glu-Trp) often cited as active component

#8 of 61 research peptides · updated
Onset
Nothing felt acutely; users judge it by fewer infections or changed immune labs over weeks to months
Lasts
cumulative; one 10-20 day course is meant to last 6-12 months
Access
Grey market
Cost / month
≈ €13–54
researchers' estimate; no listing to price
12 user reports
Glowing 2Positive 5Mixed 1Nothing 2Negative 1Bad reaction 1

  • r/MycoplasmaGenitalium· · 4 upvotesOriginal ↗

    i was taking thymalin for immune modulation post covid and i saw it was used for antibiotic resistant clamydia. i was hopeful it might be useful for mycoplasma and it was. it cleared my infection.

    Glowing10 mg/day · 10 days

    Mycoplasma genitalium after failed antibiotics; post-COVID

  • r/gravesdisease· · 2 upvotesOriginal ↗

    KLOW, THYMOSIN ALPHA 1, and Thymalin has done wonders for my Hashimotos and Diverticulitis......game changer and life saver.

    Glowing

    Hashimoto's and diverticulitis; stacked with KLOW and TA-1

  • r/Biohacking· · 2 upvotesOriginal ↗

    I’m doing 10 mg per day of thymalin morning along with 10 mg per day of Epitalon before sleep. Got some flu like symptoms on day 4.

    NegativeLongevity · 10 mg/day (with 10 mg/day Epitalon) · 4 days so far (planned 19)

    longevity course stacked with Epitalon

Users report
Thin data: about a dozen first-hand reports, most of them on a multi-peptide stack. The positive half describe fewer colds or herpes outbreaks, gone allergies, better immune labs, or a cleared lingering infection. Two felt nothing. The negatives are a flu-like day on a 10 mg/day course, raised body temperature, and one user who blamed weeks of reflux and gastroparesis on a 4-day course. A long-time HSV user later grew wary of possible autoimmune or gut effects. Felt nothing: 2 of 13 reports (~15%); most users expect nothing acute, since a course is meant to show up as fewer infections over months.
Best effects
Fewer infections (anecdotal) · improved lymphocyte markers (anecdotal) · fewer herpes outbreaks (anecdotal)
Downsides
Injection-site soreness · cost of repeated courses
Watch
Theoretical: immune stimulation in autoimmune disease (same logic as Ta1) · Original drug is a calf-thymus extract; grey-market 'Thymalin' identity and purity are unverifiable
Evidence
Approved drug — approved in Russia; small, mostly unblinded human studies from one research group (Khavinson)
Typical use
5-10 mg/day for 10 days, 1-2 courses per year.
Getting it
Russian-registered calf-thymus drug; outside Russia it is grey-market vials, often synthetic or mislabelled Thymogen/Thymulin
Stacked with
Epitalon: The classic Khavinson pairing, run as simultaneous 10-20 day courses once or twice a year; the 2003 mortality study combined them. · Thymosin alpha-1: Run together or alternated by users chasing fewer infections, HSV control or autoimmune relief. · KLOW blend: Added alongside TA-1 by HSV and Hashimoto's users who credit the whole stack.

User reports 13

  • r/MycoplasmaGenitalium· · 4 upvotesOriginal ↗

    i was taking thymalin for immune modulation post covid and i saw it was used for antibiotic resistant clamydia. i was hopeful it might be useful for mycoplasma and it was. it cleared my infection.

    Glowing10 mg/day · 10 days

    Mycoplasma genitalium after failed antibiotics; post-COVID

  • r/gravesdisease· · 2 upvotesOriginal ↗

    KLOW, THYMOSIN ALPHA 1, and Thymalin has done wonders for my Hashimotos and Diverticulitis......game changer and life saver.

    Glowing

    Hashimoto's and diverticulitis; stacked with KLOW and TA-1

  • r/Holistichealing4HSV· · 5 upvotesOriginal ↗

    For HSV2 I take 7 types of peptides: Ta1, KLOW blend (BPC-157, TB-500, GHK-CU and KPV), Thymalin, and LL-37. But I also take Lomatium twice a day which on its own reduces symptoms quite a bit, plus a number of supplements. My outbreaks and daily symptoms are much milder, but still present.

    Positive

    HSV-2; seven-peptide stack (TA-1, KLOW, LL-37) plus lomatium

  • r/Biohackers· · 3 upvotesOriginal ↗

    It's not like it was while taking it but it sure is better than before starting it. Looking forward to another course and I think although the effects aren't as strong afterwards that it does make something of a lasting change.

    PositiveSleep · one course

    sleep movement disorder

  • r/Biohackers· · 2 upvotesOriginal ↗

    -Thymalin - since I use it I don't have allergy and don't get sick as often as I used to.

    Positivecycles over about 4 years

    51-year-old running many peptides in cycles

  • r/Biohacking· · 1 upvotesOriginal ↗

    Afterward, the illnesses became significantly less frequent; whether the drug actually worked—since it’s designed to boost immunity—or I simply outgrew the problem, I can't say for sure. But it seemed to do the trick.

    Positivecourse of 10 injections · one 10-injection course

    child with recurrent colds/bronchitis, prescribed in the 1990s (Russia)

  • r/greyhairreversal· · 1 upvotesOriginal ↗

    I think the base of Epitalon and Thymalin and NAD+ made a big difference. I've felt a lot better within myself recently and I think it's because I'm just starting to feel the effects of the peptides I started taking a year ago.

    PositiveLongevity · 5 mg/day · Injection · two 20-day courses a year apart

    anti-aging course with Epitalon, NAD+ and later Melanotan II

  • r/Herpes· · 6 upvotesOriginal ↗

    Since using thymic/immune peptides (from a reputable supplier) - specifically Thymalin, Thymulin, and TA-1 -- I have absolutely nothing, not even the tiniest symptom, for more than a year.

    Mixedcourses over about a year

    HSV-2 and EBV; stacked with Thymulin and TA-1

  • r/Biohacking· · 1 upvotesOriginal ↗

    Ran a 10 day course of Thymalin, but didn't expect to feel anything.

    NothingLongevity · 10 days

    65-year-old on TRT and retatrutide

  • r/covidlonghaulers· · 1 upvotesOriginal ↗

    I also tried ARA-190 (bad reaction), TA1 (no effect), GHC-CU (no effect) and Thymalin (no effect).

    Nothing

    long COVID

  • r/Biohacking· · 2 upvotesOriginal ↗

    I’m doing 10 mg per day of thymalin morning along with 10 mg per day of Epitalon before sleep. Got some flu like symptoms on day 4.

    NegativeLongevity · 10 mg/day (with 10 mg/day Epitalon) · 4 days so far (planned 19)

    longevity course stacked with Epitalon

  • r/AskDocs· · 1 upvotesOriginal ↗

    I went from having nightmares almost every night to never having nightmares again. Concurrent with my sleep improvement, I began to suffer from acid reflux and gastroparesis that prevents me from eating, and as a result I've become quite unhealthy and malnourished.

    Bad reactionSleep · 4 days

    nightly nightmares

  • r/Biohackers· · 19 upvotesOriginal ↗

    I managed to improve my immune system across the board on biomarkers by using Thymalin, documented in this 7 minute video. I haven't been sick or had a herpes outbreak since using it either.

    Positivevendor-adjacent

    longevity self-experimenter, history of herpes

Safety

Tier by safety barStrict CautionBalanced CautionEvidence only Caution

Seen harmMechanismData gapSilent harmProduct

Seen harm 1/3
The Russian label lists only possible allergic reactions and no study reports serious events, but there is no systematic safety reporting; one first-hand report describes a month of reflux and gastroparesis, confounded. Thymalin, Russian label (Vidal) ↗r/AskDocs: reflux and gastroparesis for a month after Thymalin ↗
Mechanism 2/3
A calf-thymus peptide extract given to stimulate immunity, so autoimmune or inflammatory flares are credible, as with thymosin alpha-1; chronic high doses caused thymic involution in animals. Thymalin, Belarus label: not studied in controlled trials; thymic involution in animals at chronic high doses ↗
Data gap 1/3
Registered in Russia, but its own Belarus label says it was not studied in controlled trials; the human data are open studies from one group (266 elderly over 6-8 years, 80 COVID patients). Thymalin, Belarus label: not studied in controlled trials; thymic involution in animals at chronic high doses ↗Kuznik et al. 2021: Thymalin in older patients with severe COVID-19, n=80 ↗
Silent harm 1/3
Allergic, flu-like and immune effects would be noticed within days.
Product 3/3
Outside Russia it is grey-market injectable vials, often synthetic or mislabelled thymulin; as an undefined extract its purity cannot even be specified. Mendias & Awan 2026 preprint: 6,441 grey-market peptide samples, 42-71% failed quality criteria, 15% had endotoxin ↗
Never if
Active autoimmune disease or immunosuppression · Pregnancy or breastfeeding (label)

Where to buy 4 in Europe · 6 total

ShopFormPricePer mgTesting
CosmicNootropicRUpowder · 100 mg€8291 USD€0.82/mgNo public testsout of stock
Nootropic SourceUSpowder · 100 mg€125138.95 USD€1.25/mgOwn COA
Europa-PeptideEU · PLpowder · 10 mg€25€2.49/mgOwn COA
Particle PeptidesEU · SKpowder · 20 mg€59€2.93/mgOwn COA
Baltic PeptidesEU · LTpowder · 10 mg€40€4.00/mgThird-party tested
CertaPeptidesEU · ROpowder · 10 mg€42€4.20/mgThird-party tested

Studies 4

Sources 1

More in Immune all 6 →

  1. 1Thymosin alpha-1 SDAAVDTSSEITTKDLKEKKEVVEEAEN (28 residues) Caution Injection≈ €38–40 / month60%positive47 reportsThymic immunomodulator approved abroad for hepatitis B/C; used to cut down on colds.
  2. 2Thymulin Caution Injection / Topical49%positive4 reportsZinc-bound thymic nonapeptide; injected for immunity, sprayed on scalps for hair. 1980s data only.
  3. 3Chonluten Caution Oral / Injection≈ €72–100 / month43%positive1 reportsKhavinson's 'bronchial' tripeptide EDG; no airway study exists, and only one first-hand report was found.
  4. 4VIP HSDAVFTDNYTRLRKQMAVKKYLNSILN (28 residues) Caution Nasal / IV≈ €36–540 / month50%positive30 reportsPotent vasodilating neuropeptide used in mould-illness (CIRS) protocols under a doctor.Significant cardiovascular action (vasodilation/hypotension) and broad immunomodulation; a supervised CIRS therapy, not a general-health peptide.
  5. 5LL-37 LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (37 residues) Excluded Topical / Injection≈ €45–110 / month53%positive26 reportsEndogenous antimicrobial peptide for chronic infections/dysbiosis; pro-inflammatory, pro-tumour in places.Pro-inflammatory/autoimmune and context-dependent pro-tumour activity, plus FDA-noted reproductive effects.

Sequence beads

Each bead is one amino acid in the peptide's chain, coloured by its side chain: grey for non-polar, cyan for polar, blue for positively charged and fuchsia for negatively charged. Length and mix tell related peptides apart at a glance, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4. The colours describe chemistry only and predict neither effect nor safety.

non-polarpolarpositivenegative

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. Kept peptides rank by the same reports' mean grade, shrunk the same way, and excluded ones follow in that order.

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 alongside the computed scores until reports arrive.

Safety tier

Each peptide is tiered clean, caution or excluded from its five risk axes under the chosen safety bar. An excluded peptide has a plausible route to serious harm, 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 exclude a peptide. 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.

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.

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.