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Thymosin Alpha-1 (Injectable)
Immune

Thymosin Alpha-1 (Injectable)

Immune-modulating peptide for chronic infections and immune support.

The pepti Pen cartridge for this treatment is sold out right now. The vial is the same medication at our best price.

All-in monthly price

$249

No membership fee · this is the full price · free shipping · avg 4-week supply

Medication, provider care, labs & dose adjustments — all in one price.
~28-day supply. Your provider sets your exact dose, so yours may vary — your refill arrives as you finish the last one.
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This treatment requires licensed provider review and approval. Treatment is not guaranteed. If prescribed, medication is fulfilled by a licensed U.S. pharmacy where permitted by law. Compounded medications are not FDA-approved or FDA-cleared.

Dr. Gene
Physician Reviewed

Reviewed by Dr. Gene, MD · Board-certified Family Medicine

Every Pepti prescription is reviewed by a licensed U.S. physician before it's dispensed — and only provided if clinically appropriate.

About

Thymosin Alpha-1 (Injectable)

Thymosin Alpha-1 is a naturally occurring peptide that plays a critical role in immune system regulation. It enhances the function of T-cells, dendritic cells, and natural killer cells. FDA-approved in over 35 countries for hepatitis B and C, and widely used off-label for immune support in chronic infections, autoimmune conditions, and as an adjunct to cancer immunotherapy.

Benefits
Boosts immune function
Supports T-cell activity
Used for chronic infections
Anti-inflammatory
Enhances vaccine response
Supply per fill
28-day

About a 4-week supply supply at the standard prescribed dose — your physician confirms exact dosing.

Physician review
24 hrs

A licensed US physician reviews your intake and prescribes when appropriate.

FDA-registered pharmacy
503A

Compounded fresh at a US pharmacy and shipped cold-chain to your door.

Shipping, always
Free

Every order ships free — medication, physician care and refills, one all-in price.

Formulation
Injectable vial5 mL · 2 mg/mL
Thymosin α-110 mg
Pepti Pen cartridge3 mL cartridge (300 units) · 5 mg/mL
Thymosin α-115 mg

Amounts shown are per unit. Compounded fresh at a US FDA-registered pharmacy.

Quality

Every batch independently tested

Every medication batch dispensed through Pepti is independently tested by a qualified third-party laboratory for applicable quality and safety standards before the pharmacy releases it. Batches are tested to the same standard used by 503B outsourcing facilities.

USP <71>
Sterility

Confirms the finished preparation is free of viable microorganisms.

USP <85>
Bacterial endotoxins

Screens for endotoxins that can cause fever or inflammatory reactions.

Assay
Potency

Verifies the labeled concentration of the active peptide is what is in the vial.

HPLC
Purity

Checks the active peptide against impurities and degradation products.

Mass spectrometry
Identity

Confirms the peptide in the vial is the correct molecule.

USP <791>
pH

Confirms the solution sits within the range specified for injection.

USP <788>
Particulate matter

Checks the finished vial for visible and sub-visible particles.

USP <1207>
Container closure integrity

Confirms the vial seal holds so sterility is maintained through the beyond-use date.

Recent lots
  • Lot 100526-THY-10

    Tested 2026-10-07 · Biolink Life Sciences Carolinas

    Sterility

    Sterile

    Endotoxin

    <2 EU/mL

    Potency

    99.7%

  • Lot 100526-THY-2

    Tested 2026-10-07 · Biolink Life Sciences Carolinas

    Sterility

    Sterile

    Endotoxin

    <2 EU/mL

    Potency

    100.1%

  • Lot 092826-THY-10

    Tested 2026-09-30 · Biolink Life Sciences Carolinas

    Sterility

    Sterile

    Endotoxin

    <2 EU/mL

    Potency

    99.1%

Compounded by licensed U.S. pharmacies. Prescribed by licensed medical providers. Shipped directly to patients.Documentation available upon request →View lab results by lot →
Your protocol

How Thymosin Alpha-1 is prescribed.

Who it's for
  • Adults whose physician is supporting immune function
  • Patients with recurring infections or chronic immune stress
  • People who want an immune peptide with a long clinical history

Your physician decides whether Thymosin Alpha-1 is appropriate for you after reviewing your intake and labs.

Directions & duration

Inject 0.25 mL (25 units) subcutaneously once daily Monday through Friday.

Cycle. Ongoing monthly treatment. Most patients notice the most change in the first two months and continue for lasting support.
Ready for more? When you're ready for more, ask your physician to double your dose. If approved, the extra vial is billed at cost and applied to your next fill.
Directions shown are the pharmacy's standard for this preparation. Your prescription label is the final word.
What's included
  • Licensed physician review of your intake, history, and labs
  • Medication compounded to your prescription by a PCAB-accredited, FDA-registered pharmacy
  • Every batch independently tested before release
  • Sterile syringes and alcohol prep pads for injectables
  • Tracked delivery to your door, refills on schedule
  • Message your physician anytime; dose changes without an appointment
Storage & handling
  • Store refrigerated (36–46°F / 2–8°C) at all times, including before first use.
  • One vial is your monthly supply. A fresh vial ships every 28 days on your refill schedule, so you're always well inside the beyond-use date on your label.
  • Protect from light. Wipe the stopper with an alcohol pad before every draw.
  • Dispose of syringes in the sharps container per the included instructions.
What to expect

A typical course of Thymosin Alpha-1.

TimeframeWhat patients commonly report
Weeks 1–2Most patients notice little day to day early on.
Weeks 3–8Fewer or shorter illnesses is the most commonly reported change, though this varies widely.
OngoingLong-term treatment. Your physician adjusts the dose over time as your goals evolve.
Individual results vary. Compounded medications are not FDA-approved; a licensed physician determines whether treatment is appropriate and monitors your progress.
The full reference

Everything published
about Thymosin Alpha-1.

How it is described to work, pathway by pathway. What the research shows and what it does not. Where it stands with the FDA, dated and sourced.

Read the reference
14
References

peer-reviewed, each verified on PubMed

14
Sections

mechanism, evidence, dosing, safety, FAQ

Sep 24
FDA status verified

2026 · checked against fda.gov, not memory

The science

How Thymosin Alpha-1 works, and what the research shows.

How it works

Thymosin Alpha-1 is a 28-amino-acid peptide produced by the thymus gland.

It enhances T-cell maturation, dendritic cell function, and NK cell activity.

Used in 35+ countries for immune modulation.

Clinical evidence
  • Thymosin Alpha-1 has substantial human use: as thymalfasin (Zadaxin) it is approved in over 30 countries for chronic hepatitis B and C and as an immune adjuvant, and randomized trials have studied it in severe infections and sepsis with signals of benefit in immune-compromised patients.

  • It is not FDA-approved in the US, where it is available through compounding pathways under physician direction.

Full references with PubMed links are listed further down the page.

References

  1. Dominari A, Hathaway Iii D, Pandav K et al.. Thymosin alpha 1: A comprehensive review of the literature · World J Virol (2020) · PMID 33362999
  2. Pierluigi B, D'Angelo C, Fallarino F et al.. Thymosin alpha1: the regulator of regulators? · Ann N Y Acad Sci (2010) · PMID 20536444
  3. Wu J et al.. The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial · BMJ (2025) · PMID 39814420
  4. Wu J et al.. The efficacy of thymosin alpha 1 for severe sepsis (ETASS): a multicenter, single-blind, randomized and controlled trial · Crit Care (2013) · PMID 23327199
  5. Naing C et al.. Thymosin-ɑ1 for people with chronic hepatitis B · Cochrane Database Syst Rev (2026) · PMID 42713852
  6. Chien RN et al.. Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial · Hepatology (1998) · PMID 9581695
  7. Yang YF et al.. Comparison of the efficacy of thymosin alpha-1 and interferon alpha in the treatment of chronic hepatitis B: a meta-analysis · Antiviral Res (2008) · PMID 18078676
  8. Ciancio A et al.. Thymosin alpha-1 with peginterferon alfa-2a/ribavirin for chronic hepatitis C not responsive to IFN/ribavirin: an adjuvant role? · J Viral Hepat (2012) · PMID 22233415
  9. Maio M et al.. Large randomized study of thymosin alpha 1, interferon alfa, or both in combination with dacarbazine in patients with metastatic melanoma · J Clin Oncol (2010) · PMID 20194853
  10. Liu Y et al.. Thymosin Alpha 1 Reduces the Mortality of Severe Coronavirus Disease 2019 by Restoration of Lymphocytopenia and Reversion of Exhausted T Cells · Clin Infect Dis (2020) · PMID 32442287
  11. Camerini R, Garaci E. Historical review of thymosin α 1 in infectious diseases · Expert Opin Biol Ther (2015) · PMID 26098768
  12. Gravenstein S, Duthie EH, Miller BA, Roecker E, Drinka P, Prathipati K, Ershler WB. Augmentation of influenza antibody response in elderly men by thymosin alpha one. A double-blind placebo-controlled clinical study · J Am Geriatr Soc (1989) · PMID 2642497
  13. Carraro G, Naso A, Montomoli E, Gasparini R, Camerini R, Panatto D, et al.. Thymosin-alpha 1 (Zadaxin) enhances the immunogenicity of an adjuvated pandemic H1N1v influenza vaccine (Focetria) in hemodialyzed patients: a pilot study · Vaccine (2012) · PMID 22178096
  14. Niu W, Li Z, Li Z et al.. A Prospective and Randomized Control Study on Effects of Thymalfasin for Injection on Perioperative Immune Function and Long-term Prognosis of Patients with Colorectal Cancer · Biotechnol Genet Eng Rev (2024) · PMID 37248723

Citations are provided for educational purposes. They do not constitute medical advice. Always discuss any peptide protocol with your prescribing physician.

Important safety information

+

Possible side effects

• Mild injection site reactions

Do not use if you have

• Active cancer or history of cancer (unless approved by oncologist)
• Pregnancy or breastfeeding
• Severe kidney or liver disease
• Known allergy to the peptide or excipients
• Active autoimmune disease (use with physician guidance)

If you experience severe side effects, call 911 or go to your nearest emergency room.

How supplied

5 mL multi-dose vial, Thymosin A-1 2 mg/mL (10 mg Thymosin A-1 per vial); as the Pen: 3 mL pre-filled Pen cartridge containing 15 mg Thymosin alpha-1

Common questions

Frequently asked
about Thymosin Alpha-1 (Injectable).

Thymosin Alpha-1 is a naturally occurring peptide that plays a critical role in immune system regulation. It enhances the function of T-cells, dendritic cells, and natural killer cells. FDA-approved in over 35 countries for hepatitis B and C, and widely used off-label for immune support in chronic infections, autoimmune conditions, and as an adjunct to cancer immunotherapy. Thymosin Alpha-1 is prescription-only at Pepti: a licensed physician reviews your assessment and, if appropriate, prescribes it to be compounded by a state-licensed, FDA-registered pharmacy.

33 more questions about Pepti, answered.

One vial is your monthly supply at the dose your physician prescribes. A fresh vial ships about every 28 days, and the date moves if your physician changes your dose. Store it as the pharmacy label directs, refrigerated.

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Pharmacy network accreditation

PCAB-accredited pharmacies on every order.

Every fulfillment runs through a PCAB-accredited pharmacy.

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PCAB — Pharmacy Compounding Accreditation Board · Accredited
  • Rigorous third-party quality & safety inspections
  • Cleanliness and sterile processes
  • Proper ingredient sourcing
  • Accurate dosing and formulation
  • Staff training and procedures
  • Accredited by NABP & ACHC