Is Splenin FDA approved?

Splenin is not evaluated or approved by the FDA. It is discussed for research and educational purposes only, not as medical guidance.

Is Thymulin FDA approved?

Thymulin is not evaluated or approved by the FDA. It is discussed for research and educational purposes only, not as medical guidance.

How is Splenin administered in research settings?

In research settings, Splenin is typically administered via the subcutaneous or intramuscular routes. PeptideBase does not provide dosing or administration instructions.

How is Thymulin administered in research settings?

In research settings, Thymulin is typically administered via the subcutaneous route. PeptideBase does not provide dosing or administration instructions.

Home›Research›Compare›Splenin vs Thymulin

Peptide Comparison

Splenin vs Thymulin

Q: What is the difference between Splenin and Thymulin?

Splenin: Spleen-derived tetrapeptide bioregulator; normalizes leukocyte and platelet production; modulates splenic immune cell activity Thymulin: Zinc-dependent peptide that promotes T-lymphocyte differentiation, enhances natural killer cell activity, and regulates cytokine balance. Requires zinc cofactor for biological activity.

Both are Immune & Thymic peptides.

Splenin

Spleen peptide bioregulator

RecoveryNot EvaluatedResearch Only

Half-life: Unknown

1 providers listed

Full Splenin profile →

Thymulin

FTS

RecoveryNot EvaluatedResearch Only

26 providers listed

Full Thymulin profile →

Bottom line

Thymulin is carried by more providers on PeptideBase (26 vs 1); otherwise the two are closely matched on the measures we track.

Quick Verdict

Splenin

Evidence

Review-level

Thymulin

Evidence

Preclinical

Which One Should You Choose?

Your goal	Better option
More provider options (1 vs 26)	Thymulin

Research summary only — not medical advice. Consult a qualified provider before making any decisions.

Side-by-Side Comparison

Splenin

Thymulin

Mechanism Family

Immune & Thymic

Half-life

Unknown

—

FDA Status

not evaluated

Admin Routes

subcutaneous, intramuscular

subcutaneous

Availability

Research Only

Providers

1 listed

26 listed

Avail. Notes

Russian peptide bioregulator from spleen (Khavinson Institute). Immunomodulatory. No FDA approval, no NDA or IND. Not on any FDA list. Research chemical in US only.

—

Research Evidence

Splenin

Review-levelReview · 2 key studies · most recent 2022

Thymulin

PreclinicalReview · 2 key studies · dated evidence base — most recent 2009

Research Citations

Splenin

Review2022 · International Journal of Molecular Sciences

Neuroepigenetic Mechanisms of Action of Ultrashort Peptides in Alzheimer's Disease

Review2020 · Stem Cell Reviews and Reports

Peptide Regulation of Cell Differentiation

Thymulin

Review2009 · Annals of the New York Academy of Sciences

The thymus-neuroendocrine axis: physiology, molecular biology, and therapeutic potential of the thymic peptid…

Animal2007 · International Immunopharmacology

In vivo treatment with a nonapeptide thymic hormone, facteur thymique serique (FTS), ameliorates chronic coli…

About Splenin

Spleen-derived tetrapeptide bioregulator; normalizes leukocyte and platelet production; modulates splenic immune cell activity

Research Areas

immune restorationblood cell productionsplenic function support

About Thymulin

Zinc-dependent peptide that promotes T-lymphocyte differentiation, enhances natural killer cell activity, and regulates cytokine balance. Requires zinc cofactor for biological activity.

Research Areas

immune modulationT-cell maturationNK cell supportanti-inflammatory

Safety Profile

Information below reflects published research data only — not medical advice. Consult a qualified provider before use.

Splenin

No established clinical contraindications. This is an investigational compound with limited human data and has not been evaluated by the FDA for safety in this context. Consult a qualified clinician.

Thymulin

Absolute Contraindications

Under clinical review

Being verified by our medical team before we display contraindications for this peptide.

Find Providers

Where to source these peptides

Providers offering

Splenin

1 listed

Browse directory →

Providers offering

Thymulin

26 listed

Browse directory →

PeptideBase lists providers for educational research purposes only. Always consult a qualified healthcare professional before obtaining or using any peptide.

More Immune & Thymic Comparisons

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Educational research tools — not medical advice.