StartU.S. status
An offer does not settle the U.S. rules.
A clinician’s licence gives permission to practise medicine. A prescription names the medicine ordered for a patient. The ingredient rules below decide what a pharmacy may use to make that medicine.
There is no approved U.S. product.
As of September 28, 2026, no thymosin alpha-1 product held U.S. approval in the FDA records.
There is no official U.S. prescribing label: the drug instructions for clinicians reviewed by the FDA. The FDA is the U.S. Food and Drug Administration.
- A prescription does not turn a product into an FDA-approved medicine.
- A drug code in a government directory is not proof of approval.
Pharmacy-made medicines have ingredient rules.
With compounding, medicine is prepared for an individual patient’s need instead of supplied as a finished factory product.
The FDA’s explanation says compounded medicines do not receive its review before they are marketed.
The ingredient rules below were checked as of September 26, 2026.
A pharmacy preparing a prescribed medicine for an identified patient is one kind of compounder. The law calls this a 503A pharmacy. The FDA’s ingredient guide sets three conditions for the ingredients it uses. The pharmacy must meet the condition that applies.
- If an official ingredient standard exists, the ingredient must meet it. This standard sets written quality requirements. The pharmacy must also follow the written rules for making the medicine.
- If no official standard exists, the ingredient must already be used in an FDA-approved medicine.
- If neither of those conditions applies, this type of pharmacy must find the ingredient on the FDA’s list of permitted extra ingredients.
FDA records checked September 28, 2026 show that thymosin alpha-1 meets none of those three conditions.
Taken together, these records and rules mean a 503A pharmacy cannot lawfully make it from raw ingredients.
A withdrawn request is not clearance.
On its page marked April 22, 2026, the FDA lists this ingredient among requests taken back by their submitters.
The same entry still raises concerns about ingredient quality and the body reacting to the medicine as an invader.
- Taking back the request did not approve the ingredient or place it on the allowed list.
- An FDA panel advised against adding two forms of the ingredient at its December 4, 2024 meeting. They were listed as thymosin alpha-1 (free base) and thymosin alpha-1 acetate. These names identify forms of the ingredient, not ways of taking it.
- The panel’s advice did not itself change the law.
- By September 28, 2026, the FDA had made no final rule specifically adding or excluding this ingredient.
The existing ingredient conditions still apply while the list stays unchanged.
Approval elsewhere does not open U.S. access.
As of September 28, 2026, Italy’s drug register confirmed a prescription medicine called thymalfasin (Zadaxin).
Its use there is narrow: an addition to flu vaccination for people with weakened defences against illness, as FDA and European records describe it.
The FDA says that personal imports of drugs without U.S. approval are generally against U.S. law, as of September 26, 2026.
- Ask the prescriber to show the U.S. approval record for the exact medicine, or the ingredient rule that permits the pharmacy to make it.
- Ask for that explanation in writing before agreeing to pay.