Thymosin Alpha-1 + Thymalin

What are Thymosin Alpha-1 and Thymalin?

Thymosin Alpha-1 (Tα1, TA1, thymalfasin) is an N-terminally acetylated 28-amino-acid peptide (approx. 3,108.3 g/mol). Report content on a defined active-peptide basis — acetate/water/counterions can change labeled mass.

Thymalin is not one peptide. The registered Russian product is a lyophilized extract from calf/young-cattle thymus (a current 10 mg presentation also contains 20 mg glycine). Proposed short sequences (KE, EW, EDP) do not convert a 10 mg vial into 10 mg of any single defined peptide.

Thymosin Alpha-1, Thymalin, and thymulin are not interchangeable

Any source that describes Thymalin as a single 28-amino-acid peptide is confusing it with Thymosin Alpha-1.

Has Thymosin Alpha-1 + Thymalin been studied directly?

No controlled trial of the exact combination was located. Parallel discussion in clinic or marketing copy is not combination evidence.

Both products are described as affecting T-cell, dendritic-cell, cytokine, and innate-immune pathways. Overlap could produce complementarity, redundancy, antagonism, excessive activation, or no meaningful interaction. The current Russian Thymalin monograph specifically advises avoiding simultaneous products with a similar mechanism of action — that does not prove harm, but it argues against treating the stack as automatically synergistic.

A valid synergy study needs a four-arm design (control, Tα1 alone, Thymalin alone, combination) with a prespecified interaction term.

U.S. and international medicinal status

Thymalfasin has national medicinal approvals outside the United States (e.g., Zadaxin). There is no U.S. prescribing label for Thymosin Alpha-1 or for the combination.

FDA reviewed Thymosin Alpha-1 free base and acetate-related bulk substances in 2024, raising characterization, impurity, aggregation, injectable-formulation, and immunogenicity concerns, and proposed against 503A Bulks List inclusion. As of FDA’s May 2026 update, Tα1 remained in 503A Category 2 — a compounding-policy classification, not a finding that all international thymalfasin products are equivalent or ineffective.

Thymalin is a registered prescription medicine in Russia (10 mg lyophilizate for IM solution). That registration does not create a U.S. dosage standard or establish safety of independently sourced research extracts. The exact two-component protocol has not been reviewed as a medicinal product.

Human Thymosin Alpha-1 research dosages

Tα1 schedules are indication-specific and should not be blended into one universal “immune dose.”

TESTS (2025): 1,106 adults with sepsis randomized; 1,089 in mITT. 28-day mortality 23.4% Tα1 vs 24.1% placebo (HR 0.99). Secondary/safety outcomes did not differ significantly. Immune-biomarker plausibility does not guarantee clinical benefit.

Human Thymalin research and medicinal dosages

Reported Thymosin Alpha-1 + Thymalin protocols

Three patterns circulate: (1) evidence-anchored separate-vial template, (2) more aggressive online clinic stacks, and (3) unlabeled-ratio commercial “complex” vials.

Complete fixed-exposure research protocol

Prospective, hypothesis-generating template only. It does not establish that the combination is appropriate for a participant or that biomarker changes equal clinical benefit.

Design preference: randomized 2×2 factorial; otherwise prospective observational with explicit inability to test synergy. No dose escalation, catch-up doubling, or automatic repeat cycle.

Missed doses: record as missed — do not double, do not add Thymalin days, do not compress two Tα1 doses into adjacent days. Accountability must capture identity, free-base/acetate/extract basis, lot, diluent, volume, route, site, storage, deviations, and AEs for every administration.

Reconstitution and concentration math (separate vials)

Tα1: cleanest protocol uses a 1.6 mg single-dose vial to 1.0 mL (1.6 mg/mL = 100 U-100 volume units for the full dose). For a 10 mg research vial, FDA-reviewed characterization described solubility up to ~2 mg/mL; concentrations above that (e.g., 2 mL → 5 mg/mL, 3 mL → 3.33 mg/mL) exceed the reviewed clinical concentration anchor.

Thymalin: preserve product-specific diluent and IM route. The severe-COVID report used 10 mg in 2 mL 0.9% NaCl (5 mg/mL). U-100 “units” are volume markings only — they do not authorize insulin-syringe IM technique or SC substitution.

A 2 mL Thymalin administration exceeds a 1 mL U-100 syringe capacity — do not split or reroute merely to fit a device without protocol support. Extract mg cannot be converted to mg of KE, EW, EDP, or Tα1 without validated composition data.

Why the components should remain in separate vials

Mixing creates unanswered questions: extract effects on Tα1 stability/aggregation; shared pH/tonicity/excipients; proteases or contaminants; sterility and particulates; post-mix assay of both components; which component caused an AE; and how to retain route-specific evidence if one is studied SC and the other IM.

No compatibility study was located. Separate preparation is the scientifically cleaner default.

How might the combination work?

Tα1 themes under investigation: dendritic-cell maturation, TLR-related signaling, T-cell differentiation/function, NK activity, Th1/interferon-related responses — often framed as modulation rather than one-direction stimulation.

Thymalin themes: T/B balance, phagocytic activity, hematopoietic differentiation pathways, monocyte/macrophage inflammatory signaling, and short-peptide gene-expression hypotheses.

Unknown for simultaneous exposure: Tα1 PK, Thymalin peptide distribution, cytokine magnitude, autoimmune/hypersensitivity risk, infection outcomes, long-term immune function, optimal timing/route/ratio. Similar pathways do not prove the products “cover more of the immune system.”

Expected results and timeline

Feeling more energetic, sleeping differently, or “getting sick less” during a brief cycle is not a validated measure of thymic rejuvenation.

Safety and adverse effects

No reliable exact-combination incidence data exist. Component-level local reactions and allergy are the clearest near-term concerns; broader uncertainties include immune dysregulation, aggregation/immunogenicity for Tα1, and animal-extract contamination for Thymalin.

Neither component should substitute for diagnosis, antimicrobial treatment, respiratory support, sepsis care, or vaccination. The neutral Phase 3 Tα1 sepsis result warns against extrapolating biomarker hypotheses into emergency treatment claims.

Route of administration

Storage and stability

Tα1: FDA review emphasized formulation sensitivity and aggregation. Reviewed material described reconstituted free-base stability of approximately 2–7 days at 4°C; longer storage needs colder conditions and formulation-specific support. Do not infer a 28-day in-use period from bacteriostatic water alone.

Thymalin: unopened Russian product listed at 2–25°C. Reconstituted stability must come from product instructions or a validated study — a peptide fingerprint can change even when the solution remains clear.

Discard when the supported in-use period ends, storage cannot be verified, label/lot/volume/date is missing, integrity is compromised, appearance is abnormal, contamination is suspected, or a lot-quality failure is identified.

Common claims vs evidence

Evidence ladder

The proposed schedule is reproducible because its math and timing are explicit. Reproducibility does not make it a validated therapy.

Thymosin Alpha-1 + Thymalin vs other thymic combinations

WADA and tested sport

Neither Thymosin Alpha-1 nor Thymalin was found by name on the 2026 WADA Prohibited List reviewed for this page. Unlike BPC-157 or prohibited thymosin-beta-4-related categories, this pair is not specifically identified in that list text.

That is not athlete-specific clearance. Anti-doping interpretation can depend on pharmacological category, national approval, product contents, route, TUE rules, and contamination. Thymalin’s heterogeneous composition means an athlete cannot infer every constituent from the product name — obtain a current written determination from the responsible authority before exposure.

Bottom line

Thymosin Alpha-1 + Thymalin is not a single peptide blend with an established ratio. It pairs a defined synthetic 28-aa peptide with a heterogeneous bovine-thymus extract. No controlled study has established that the pair is safer or more effective than either component alone.

The most defensible research template preserves the best-known component schedules and routes: Tα1 1.6 mg SC twice weekly for 8 weeks, plus a separate Thymalin course of 10 mg IM daily on days 1–10. That produces 25.6 mg cumulative Tα1 and 100 mg cumulative Thymalin extract, followed by 28 days without exposure. It is a proposed, auditable study schedule — not a validated treatment protocol.

Central quality rule: separate identities, separate vials, separate routes, separate assays, and separate accountability. A total-mass “complex” vial without a component ratio cannot provide a reproducible dose.

Frequently asked questions

References

• PubChem

  Thymalfasin, CID 16130571

  Compound record.

• FDA

  Thymosin Alpha-1 Related Bulk Drug Substances: PCAC review

  2024 compounding advisory review.

• FDA

  Bulk Drug Substances Nominated for Use in Compounding Under Section 503A

  Updated May 14, 2026 — Category 2 listing context.

• Wu J et al.

  The efficacy and safety of thymosin α1 for sepsis (TESTS)

  BMJ 2025;388:e082583 — Phase 3 neutral primary mortality.

• ClinicalTrials.gov

  The Efficacy and Safety of Tα1 for Sepsis, NCT02867267

  TESTS study record.

• Tuthill CW et al.

  Pilot trial of Thymalfasin to prevent COVID-19 in hemodialysis patients

  1.6 mg SC twice weekly × 8 weeks — component pilot.

• Samson-Med / Vidal

  Thymalin 10 mg Russian medicinal information

  Registered IM lyophilizate schedule context.

• Kuznik B et al.

  Peptide Drug Thymalin Regulates Immune Status in Severe COVID-19 Older Patients

  Adv Gerontol 2021 — 10 mg IM daily × 10 days observational.

• Khavinson VKh, Morozov VG

  Peptides of pineal gland and thymus prolong human life

  Neuro Endocrinol Lett 2003 — Thymalin ± Epithalamin, not Tα1.

• WADA

  2026 Prohibited List

  Neither name specifically listed in reviewed text — not athlete clearance.