What peptides are studied for immune support?

Research in this area centers on thymic hormones (thymosin alpha-1, thymulin) and the Khavinson bioregulators — the thymus extracts thymalin and Vladonix, and the short synthetic peptides vilon, splenin and chonluten. The list on this page is drawn from peptides in our database whose mechanism family is immune/thymic and that carry an evidence signal.

Are immune-support peptides FDA approved?

None of the peptides on this page is FDA-approved for immune support. Thymosin alpha-1 is used clinically in some other countries as an adjuvant in chronic hepatitis; the rest are research compounds or Russian-registered preparations. Each peptide’s profile page shows its current regulatory status. This page is educational and does not recommend use.

What is the difference between thymulin and thymalin?

Thymulin is a single, defined nine-amino-acid hormone produced by thymic epithelial cells; it needs a bound zinc ion to be biologically active. Thymalin is a thymus-extract preparation containing a mixture of short peptide fragments, developed by the Khavinson school in Russia. The similar names are the only thing they share.

Educational use only — not medical advice

Peptides Researched for Immune Support

This guide lists peptides studied in the context of immune function — chiefly thymic hormones and Khavinson bioregulator peptides — ranked by our evidence signal (study grade and citation count). It is educational information only — not medical advice, dosing guidance, or a recommendation to use any compound.

Most of this page traces back to the thymus, the organ in which T-cells mature and whose output declines with age. The compounds fall into two kinds. Defined peptides with a known sequence: thymosin alpha-1, a 28-amino-acid peptide; thymulin, a nine-amino-acid thymic hormone that is biologically inactive unless bound to zinc; and the short synthetic Khavinson peptides vilon (a thymus-derived dipeptide), splenin (spleen-targeted) and chonluten (bronchial and lung-targeted), which our database classes in the same immune/thymic mechanism family. And the Khavinson school’s thymus-extract bioregulators, thymalin and Vladonix — mixtures of short peptide fragments rather than a single characterized molecule. Thymulin and thymalin are routinely conflated because of their names; they are not the same thing.

The evidence is not uniform across the set, and the ranking below reflects that. Thymosin alpha-1 carries the meaningful clinical literature — it has been studied in randomized trials as an immune adjuvant in chronic viral hepatitis and is used clinically in some countries for that purpose, though it is not FDA-approved. The bioregulator preparations rest mainly on Russian-origin observational and preclinical work that has not been independently replicated to Western standards, and thymulin’s human data are limited. Regulatory status varies and none of these compounds is approved for immune support. The list is ordered by our evidence signal (study grade and citation count), and each profile page carries the mechanism, regulatory status and citations behind it, so the comparison is grounded in what the research actually supports rather than in marketing claims.

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RecoveryResearch Only

Thymosin Alpha-1

Thymosin Alpha · Tα1 · Zadaxin

Thymosin alpha-1 (thymalfasin; Zadaxin) is a 28-amino-acid synthetic peptide corresponding to the N-terminal sequence of prothymosin alpha, developed as a biological response modifier with established clinical use outside the United States for chronic viral hepatitis and as an immune adjuvant in cancer and immunocompromised patients. Thymalfasin modulates innate and adaptive immune responses by upregulating Toll-like receptor expression and dendritic cell maturation, enhancing T-helper 1 cytokine signaling, and potentiating antigen-specific T-cell responses in settings of impaired immune function. A prospective multicenter randomized controlled trial demonstrated that combination therapy with thymosin alpha-1 and entecavir improved serological outcomes in HBV-related compensated cirrhosis compared to entecavir alone, and cumulative RCT evidence supports its role as an immune adjuvant in hepatitis B and C treatment. Thymosin alpha-1 is approved in approximately 35 countries — including China, Italy, and other Asian and Eastern European markets — for hepatitis B and hepatitis C adjuvant therapy, but has not received FDA approval in the United States and is available in US-adjacent research contexts only as an investigational compound. Thymosin alpha-1 dosage: in approved clinical protocols (hepatitis B adjuvant therapy), thymalfasin is administered as 1.6 mg subcutaneously twice weekly for 26–52 weeks. This dosing schedule is derived from the pivotal trials conducted by SciClone Pharmaceuticals, which developed Zadaxin. In COVID-19 research during 2020–2021, Chinese clinical centers studied thymosin alpha-1 as an immune adjuvant in severe and critical COVID-19 patients, with published observational and small RCT data; this research context brought renewed attention to the peptide's immune-modulating properties outside the hepatitis indication. Within the recovery and immune-support peptide landscape, thymosin alpha-1 is most closely compared to thymosin beta-4 (TB-500) — the two peptides share the thymosin nomenclature but have distinct mechanisms and research profiles. Thymosin alpha-1 is an immune activator (TH1 upregulation); thymosin beta-4 is primarily studied for tissue repair and actin dynamics. Providers offering immune-modulating peptide compounds are listed in the PeptideBase directory.

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Peptides Researched for Immune Support

Peptides in This Category

Thymosin Alpha-1

Vladonix

Thymalin

Thymulin

Splenin

Chonluten

Vilon

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