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Thymalin vs Thymosin Alpha-1

Updated 11 sources

Key differences

  1. 1Thymalin is a calf thymus extract, a mix of peptides; thymosin alpha-1 is one defined synthetic 28 amino acid peptide.
  2. 2Thymosin alpha-1 has much stronger evidence by international standards and approval in several countries; thymalin is registered in Russia and former Soviet states only.
  3. 3Thymalin goes into muscle in 3 to 10 day courses; thymosin alpha-1 goes under the skin twice a week for months.
  4. 4Ta1 is one defined synthetic peptide; thymalin is a calf thymus extract, a mixture of peptides.
  5. 5Ta1 has international randomized trials; thymalin's data come mostly from one Russian group.
  6. 6Thymalin is injected into muscle in short 3 to 10 day courses; Ta1 goes under the skin twice a week for months.

Side by side

Facts from each record, in the same words as their own pages.
Thymalin and Thymosin Alpha-1 side by side
ThymalinThymosin Alpha-1
Category
  • Immune, Longevity
  • Immune, Longevity
Evidence
  • Limited human data
  • Some human trials
FDA status
  • Not FDA approvedRegulatory
  • Not FDA approvedRegulatory
WADA
  • Not confirmed
  • Not confirmed
Half-lifeNot reported
  • About 2 hours after an injection under the skin, with peak levels at about 2 hours and no build-up between doses (label).Regulatory
  • About 2 to 3 hours per guides; peak 1 to 2 hours after injection.Competitor guide
Routes
  • Intramuscular injection, Subcutaneous injection
  • Subcutaneous injection
Forms
  • Vial (powder)
  • Vial (powder)
Reported doses
  • 5 to 20 mg (intramuscular injection)
  • 5 to 10 mg (subcutaneous injection)
  • 0.8 to 3.2 mg (subcutaneous injection)
  • 40 mcg/kg (subcutaneous injection)
  • 250 to 500 mcg (subcutaneous injection)
Most cited frequency
  • Once daily
  • Twice a week
Vial sizes
  • 10 mg, 15 mg, 20 mgRegulatory
  • 1.6 mg, 5 mg, 10 mg, 20 mgRegulatory
Mixed vial keeps
  • Label and one guide: dissolve right before the injection and do not keep the mixed solution.Competitor guide
  • Zadaxin mixed with its sterile water is single use: inject immediately.Regulatory
Protocols on file
  • 10
  • 19

Doses shown are what sources report, labelled by origin. Not medical advice.

Read each in full

Sources

11 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Regulatory5

  1. Thymalin lyophilizate for IM injection 10 mgVidal (Russia), via a reference work · checked Oct 24, 2026
  2. Zadaxin injection (SIN07483P) product informationSingapore National Drug Formulary · checked Oct 24, 2026
  3. Zadaxin (thymalfasin) prescribing informationRxList, via a reference work · checked Oct 24, 2026
  4. Certain bulk drug substances that may present significant safety risksFDA · checked Oct 24, 2026

Competitor guide6

  1. Thymalin profilepeptideprotocolwiki.com · checked Oct 24, 2026
  2. Thymosin Alpha-1 (TA1) guidepeptidedosingprotocols.com · checked Oct 24, 2026
  3. Thymosin Alpha-1 (10 mg vial) dosage protocolpeptidedosages.com · checked Oct 24, 2026
  4. Thymosin Alpha-1 profilepeptidesexplorer.com · checked Oct 24, 2026