Is Thymosin Alpha-1 legal?
Not as a drug. Thymosin Alpha-1 has no FDA approval, so selling it for human use breaks federal drug law, and a 'research use only' label does not protect a seller whose site signals human use. It is not a controlled substance, and possessing it is not a federal crime. It is approved in several countries (Zadaxin), which has no effect in the US. Pharmacies cannot compound it.
DESCRIBES THE LAW · NOT LEGAL ADVICE · NO DOSING INFORMATION
Federal, compounding and sport status
CHECKED 12 OCT 2026Federal status
- Dec 4, 2024 · voted against · 17 no, 4 yes · SOURCE ↗
Sport-body status
What we couldn’t verify
State rules
NONE FOUNDWe found no state statute, board rule or enforcement action that names Thymosin Alpha-1. The federal position above applies in all 50 states and DC.
What changed at the last check
1 CHANGES| Date | Field | Was | Now | Why |
|---|---|---|---|---|
| 12 Oct 2026 | FDA Category 2 (safety risk) | on list | not on list | FDA's Category 2 page lists it under 'nominated but withdrawn', not in Category 2. source ↗ |
Questions
3 ANSWERSIs Thymosin Alpha-1 legal in the US?
Not as a drug. Thymosin Alpha-1 has no FDA approval, so selling it for human use breaks federal drug law, and a 'research use only' label does not protect a seller whose site signals human use. It is not a controlled substance, and possessing it is not a federal crime. It is approved in several countries (Zadaxin), which has no effect in the US. Pharmacies cannot compound it.
Can a pharmacy compound Thymosin Alpha-1?
Not eligible. The PCAC voted 17-4 against it on 4 Dec 2024. FDA now lists it under 'nominated but withdrawn' (no longer Category 2), which does not permit compounding.
Is Thymosin Alpha-1 banned in sport?
It is not on the WADA 2026 Prohibited List. Not named. Approved abroad as Zadaxin, so S0 does not apply; thymosin beta-4 (TB-500) is a different molecule.