Calf-thymus polypeptide extract and immunomodulator

Thymalin

aka Timalin · thymus polypeptide extract

Evidence grade
Grade C: Preliminary human data
for immune 'rejuvenation', thymus regeneration and longevity
User score too few reports (5) needs ≥ 10 reports
US FDA Not approved checked 2026-11-13
WADA 2026 Not named no clearance either · checked 2026-11-13
EU No EMA authorization found; national positions not verified. · checked 2026-11-13

Grade note: revised from B to C on independent review. The seat gave B for a Russian registration.

Goals: Longevity · Immune Compare with another peptide →

User reports

approximate — combined from two independent Reddit reads

Men 45–60

0 men aged 45–60

No reports in this group yet.

All men

0 men

No reports in this group yet.

Everyone

5 people

small sample · n = 5

Outcome negative 2 of 5 · positive 2 of 5 · unclear 1 of 5

Benefits immune 2 of 5

Side effects other 2 of 5 · fatigue 1 of 5 · heart rate up 1 of 5

Why stopped other 1 of 5 · side effects 1 of 5

Stopped 2 of 5 Used with other compounds 2 of 5

User reports are anecdata, not evidence: self-selected, unverified, often combined with other compounds.

In their words

  • “5 days later no fever, no runny nose.”

  • “Well, the 10mg version completed eliminated my seasonal allergies for 2 months.”

  • “I've got pretty strong and uncomfortable restlessness in my body (akathisia).”

  • “Both Thymalin and TA-1 gave me flu like symptoms day one. I was pretty dysfunctional. I can't afford to be out of commission”

Read summaries and method notes

Read 1. No explicitly male reporter. Four users: two immune-type improvements (a respiratory illness clearing unusually fast; seasonal allergies gone for two months on Thymalin/Epitalon), one pounding heart and severe restlessness after 10 mg, one long-term user who backed away from earlier certainty. Very sparse and stacked.

Read 2. One self-reporter from one readable thread: flu-like symptoms and being barely functional on day one from both Thymalin and Thymosin Alpha-1, so they stopped immediately (caring for a toddler). No doses or benefits reported. Too small to generalize.

Note 1. Very sparse; no male age data; two of four stacked. Thymulin-only effects were not reclassified as Thymalin.

Note 2. Only one accessible thread contained a firsthand report.

Each read counted people independently. Overlap between the two reads is estimated from shared threads and removed; counts are approximate. How we count.

Summary

Khavinson-class thymic peptide bioregulator. Dipeptide: Glu-Trp. MW: ~333 Da.

Proposed mechanism

Thymalin is an immunomodulatory calf-thymus extract. Thymic regeneration, sustained naive T-cell output, normalized immunity, direct epigenetic rejuvenation and cancer prevention are not established clinical aging benefits; laboratory and immune-marker findings do not prove these outcomes.

Distinction vs Thymosin Alpha-1: Thymosin Alpha-1 is a defined 28-amino-acid peptide; Thymalin is an extract. A proven regeneration-versus-modulation distinction has not been established in humans.

The Khavinson longevity studies: the 2003 report included 266 people across distinct programs and arms. The reported 4.1-fold mortality ratio belongs to a separate annual-treatment group of 20 versus 22 controls, with unclear randomized allocation; the two-year combination comparison was about 2.5-fold. The combination used epithalamin extract, not synthetic epitalon. These findings cannot establish longevity benefit or justify an epitalon combination. Full report.

Safety

  • Hypersensitivity, pregnancy and breastfeeding appear as contraindications in product information
  • Extract composition, immune effects and longer-term adverse events require better characterization

From labels, regulators and trials. No signal in small studies ≠ safe.

Evidence C immune 'rejuvenation', thymus regeneration and longevity

Changed B to C. The seat gave B for a Russian registration. A bare national registration cannot lift a grade unless the file can point to an adequately reported controlled trial behind it for the marketed use; otherwise Semax and Selank (also registered in Russia, graded C by another seat) would have to be B too. The cited trials are a 2003 gerontology report with unclear randomization and an 80-person single-blind single-centre COVID-19 trial - small, early, unreplicated, and not about longevity.

Human trials · 2

  1. PMID 145233632003Two reported stratified randomized placebo-controlled programs; separate annual-treatment subgroup not clearly randomized 266 people

    Older people in two gerontology programs; total includes several distinct arms and cohorts

    The authors reported lower mortality with thymalin, epithalamin or both; important design and subgroup limitations prevent reliable causal longevity conclusions. Source

  2. DOI:10.1134/S20790570210400682021Single-center randomized single-blind placebo-controlled trial 80 people

    Hospitalized adults with severe COVID-19; 36 received thymalin and 44 saline placebo alongside standard care

    The paper reported clinical improvement and lower in-hospital mortality, but the small single-center finding requires replication and does not show thymic regeneration or longevity benefits. Source

Bar length = trial size on a log scale.

Dose ranges

Reported ranges from labels and studies, with context. Not a recommendation.

  • approved label
    Russian label for adult immunodeficiency: 5–20 mg intramuscularly daily for 3–10 days, 30–100 mg per course Source on a non-primary host — not linked
  • clinical trial
    10 mg intramuscularly daily for 10 days in a severe-COVID-19 trial Source
  • clinical trial
    10 mg intramuscularly daily for 10 days per course in one historical aging program; another used five 10 mg injections at 2–3-day intervals Source on a non-primary host — not linked

Editorial ratings EDITORIAL

Editors’ judgement, 0–5. Opinion, not data; separate from grade and user score.

Not rated yet.

Sources

  1. pubmed.ncbi.nlm.nih.gov/14523363/
  2. pmc.ncbi.nlm.nih.gov/articles/PMC8654498/
  3. fda.gov/news-events/press-announcements/fda-roundup-february-13-2024
  4. wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf?embed=
  5. ema.europa.eu/en/medicines

Reddit threads read · 5

7 further sources on commercial or non-primary hosts not listed.

Research checked 2026-11-13.