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Thymosin Alpha-1
Nomination withdrawn
as of October 2026
By Stephen Kimball, 26+ years researching the health, wellness, supplement, and peptide industries
As of October 2026, thymosin alpha-1 isn’t FDA-approved for any use and isn’t on any list that lets U.S. pharmacies compound it. Its nomination was withdrawn, so it’s off FDA’s safety-risk list, but it hasn’t been moved to the “under evaluation” list and no advisory panel review has been announced. FDA says the safety information it has is inadequate to understand the risks of compounded versions. It’s sold mainly by “research use only” sites and some clinics.
Sources
Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (withdrawn table — "Thymosin-alpha 1 (Ta1)")
U.S. Food & Drug Administration
dated Apr 2026
Bulk Drug Substances Nominated for Use in Compounding Under Section 503A (categories list — absent from Category 1)
U.S. Food & Drug Administration
dated May 2026
Change log
2023
FDA places thymosin alpha-1 in Category 2.
2026
Nomination withdrawn; moves to the “nominated but withdrawn” table. Not part of the April 2026 group of 12.