Read This First
This page is not built on clinical evidence. Cost and access are commercial and legal facts, not scientific findings. They come from the regulatory record in the countries where the drug is approved and the one where it is not, and they change on timescales of months.
Thymosin alpha-1 has a list price in Italy, India and other countries where Zadaxin or a thymalfasin generic is a prescription medicine. It has no price, no prescription route and no insurance pathway in the United States, where it is unapproved, has been rejected for compounding, and is sold only through channels that do not supply the approved product.12
This page publishes no prices. What follows is what determines the money, and for this compound that begins with which country the buyer is standing in.
Why There Is No Single Price
Two Markets That Do Not Touch
In a country where thymosin alpha-1 is approved, it is priced like any prescription biologic: a manufacturer's list price, a national reimbursement decision, and a patient contribution set by the health system. In Italy, for example, Zadaxin holds a marketing authorisation for a narrow indication, vaccine adjuvancy in immunocompromised people, and its coverage follows that indication.1 The price in that market is a price for a verified finished product for a defined use.
In the United States, none of that exists. What is sold is either a compounded preparation from a pharmacy operating without a lawful basis, or research-labelled powder from a vendor. Neither is Zadaxin, and the FDA's review states that the finished foreign product "cannot be interchangeably used" with the substance.1 A US price is therefore a price for something whose identity the buyer cannot verify against any approved reference.
What a Price Normally Represents
For an approved medicine, a price sits on top of a known quantity of a known substance, made to a validated standard, for a stated indication, with a documented effect. In the approved markets, thymosin alpha-1 has all of those for hepatitis B and vaccine adjuvancy. In the US market it has none, and the effect it is sold for, immune support against everything from Lyme disease to long COVID, has no documented effect size anywhere.1
Access
Is There a Legal Route in the United States?
No. Thymosin alpha-1 is not approved, is not a component of an approved drug, and is not on the 503A bulks list. On 4 December 2024 the FDA's advisory committee voted 4 to 17 against adding it, after an FDA review of twelve proposed uses found a lack of evidence of effectiveness for every one.21 It was not among the seven peptides considered in July 2026.
There is a clinical trial route, but not in the United States. The trials recruiting are in China, mostly in oncology, and the largest, 2,500 patients in resected colorectal cancer, is at Fudan University.3
Can It Be Imported for Personal Use?
Not as a rule. Importing an unapproved drug is prohibited, and the FDA's enforcement discretion for personal use is limited to serious conditions with no US treatment, a small supply, and a US physician's involvement. Immune support is not such a condition. ONPEPS does not advise on customs law; what it can say is that a product arriving labelled Zadaxin is either a genuine foreign product outside its lawful market or a counterfeit, and the buyer cannot distinguish them.
Does Insurance Cover It?
Not in the United States, and there is nothing to appeal. Payers reimburse approved products for approved indications. In countries where it is approved, reimbursement follows the national indication, which is narrow: hepatitis B, or vaccine adjuvancy in the immunocompromised, depending on the country.1 Off-label use abroad is cash-pay there too.
Can HSA or FSA Funds Be Used?
Tax-advantaged health accounts cover qualified medical expenses, which generally requires a legitimate medical purpose and often a provider's documentation. A product that cannot lawfully be dispensed in the United States sits poorly against that. The account holder carries the consequences of a disallowed expense; the question belongs with the plan administrator.
What the Money Buys
Where Does the Spread Between Sellers Come From?
| Channel | What is supplied | What the price includes | What it does not |
|---|---|---|---|
| Pharmacy, in an approving country, on-label | Zadaxin or a national generic | A product a regulator has reviewed; a label; coverage where the indication applies | Any use beyond the national indication |
| US clinic or telehealth | Compounded thymosin alpha-1, injection or nasal spray | A consultation and a pharmacy label | Legal standing; the approved product's specification; in most cases any evidence for the use1 |
| Research vendor | Powder labelled thymosin alpha-1 | A vial | Identity, a prescription, a label, oversight |
ONPEPS publishes no prices; read this as reasoning about cost structure rather than a measured breakdown. What the spread never buys in the United States is the thing the compound's reputation rests on: the 350,000-patient safety record, which belongs to finished products made to a standard that no US seller is applying.1
What Does the Marketing Add?
The FDA catalogued the US marketing: hepatitis B, hepatitis C, HIV, chronic fatigue, inflammation, sepsis, COVID-19, Lyme disease, allergies, cancer, asthma, COPD and psoriatic arthritis.1 That list is the product. A compound sold for thirteen conditions is being sold for the buyer's condition, whatever it is, and a price attached to it is a price for hope with a molecule inside.
The Spending Decision
What Result Is Being Paid For?
For sepsis, the answer arrived in 2025: a 1,106-patient double-blind trial found 28-day mortality of 23.4 percent on drug against 24.1 percent on placebo.4 For severe pancreatitis, a 508-patient double-blind trial found no reduction in infected necrosis.5 For hepatitis B, a benefit at 24 weeks that was gone by 48.6 For COVID-19, small unblinded studies pointing one way and the FDA's reading of the meta-analyses pointing the other.1
For immune support in a person who is not septic, not in intensive care and not being treated for hepatitis B, which is the person buying it in the United States, there is no measurement at all. The compound changes immune biomarkers; the FDA found no proposed use in which that translated into a clinical benefit over standard care.1
The safety record is genuine and it is the best in this corner of the library. It is also the reason the compound is easy to sell: a product that does little harm can be sold for anything. The money is being spent on the second half of that sentence.
What Is the Risk Side of the Ledger?
Low, for the approved product. Foreign labels contraindicate it in autoimmune disease, immunosuppressed patients, children and pregnancy, and note liver enzyme flares in hepatitis B; beyond injection-site discomfort the trials found little.1 The sepsis trial's subgroup analysis raised the possibility of harm in adults under 60, which is one prespecified finding in one trial and should be weighed as such.4
Unknown, for the US product. The FDA's concern was aggregation and impurities in an injectable of unverified manufacture, and a solubility problem that makes concentrated formulations suspect.1 That risk is a property of the vial, not the molecule, and the buyer is the only person who can decide whether to accept it.
What Should Be Asked Before Paying?
Is this Zadaxin, a national generic from an approving country, a compounded preparation, or research powder? The answer determines everything else.
Are you aware the FDA's advisory committee voted 4 to 17 against compounding this in December 2024, and on what legal basis are you supplying it?2
Which trial measured the outcome you are promising for my condition?
Can I see a certificate of analysis matched to the batch I will receive, naming free base or acetate, with identity testing and not only purity?
What is the concentration, and if it is above 1.6 mg/mL, how was that achieved?
Does anyone here earn commission on product sales?
The third question is the informative one. For sepsis and pancreatitis the honest answer is a negative trial. For most other conditions it is no trial at all.
What Would Change This Page
A US Approval, a Positive Trial, or a Reversal
No company is pursuing US approval, and the FDA's advisory process has declined the compounding route. The colorectal cancer trial is the one adequately powered study in progress, and a positive result would change the oncology picture, though not the access position in the United States, where a Chinese Phase 3 result does not create a pathway.3
A Note on "Approved in 30 Countries"
The figure is the manufacturer's, from a 2014 annual report, and the FDA could not independently verify it.1 It is also a count of approvals, not of evidence, and the largest trials have been run since those approvals were granted. A seller quoting the number as a reason to pay is quoting a regulatory history, not a result.
Related ONPEPS Coverage
Thymosin alpha-1 library entry: the approvals, the trials and the December 2024 vote
Thymosin alpha-1 sourcing and quality: an approved drug from somewhere else
Tesamorelin cost and access: a specialty drug with one indication
Sources
US Food and Drug Administration. Thymosin alpha-1-related bulk drug substances: FDA review for the December 4, 2024 meeting of the Pharmacy Compounding Advisory Committee. Docket FDA-2024-N-4777. fda.gov
US Food and Drug Administration. Final Summary Minutes of the Pharmacy Compounding Advisory Committee Meeting, December 4, 2024. Approved 21 February 2025. fda.gov
ClinicalTrials.gov. NCT05086614. Thymosin-alpha 1 for Adjuvant Treatment After Radical Resection of High-risk Stage II and III Colorectal Cancer. Sponsor Fudan University. Phase 3, recruiting. Record retrieved 16 September 2026. clinicaltrials.gov/study/NCT05086614
Wu J, Pei F, Zhou L, Li W, Sun R, Li Y, et al. The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. BMJ. 2025;388:e082583. Open access. pubmed.ncbi.nlm.nih.gov/39814420
Ke L, Zhou J, Mao W, Chen T, Zhu Y, Pan X, et al. Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial. Intensive Care Med. 2022;48(7):899-909. Paywalled. pubmed.ncbi.nlm.nih.gov/35713670
Peng D, Xing HY, Li C, Wang XF, Hou M, Li B, et al. The clinical efficacy and adverse effects of entecavir plus thymosin alpha-1 combination therapy versus entecavir monotherapy in HBV-related cirrhosis: a systematic review and meta-analysis. BMC Gastroenterol. 2020;20(1):348. Open access. pubmed.ncbi.nlm.nih.gov/33076834
Not Medical or Financial Advice
Thymosin alpha-1 is a prescription medicine in some countries and an unapproved substance in the United States and Europe. Treatment decisions belong with a qualified healthcare provider. Nothing on this page is a recommendation to buy or not to buy anything; it is an account of what determines what the money would be spent on.
Sources verified 16 September 2026. Regulatory status and trial results change; re-verify before relying on anything here.