CURRENT RULES, NOT MEDICAL OR LEGAL ADVICE
A clinic offer isn't proof: check TB-500 Legal Status
See what FDA allows now, what was on its July 2026 meeting agenda, and what a pharmacy needs before making a drug for one named person.
What FDA's July 2026 meeting covered
TB-500 legal status went before an FDA review panel in July 2026, and FDA has posted no result. The agenda named "TB-500 (free base)," one lab form, and "TB-500 acetate," another form of the same ingredient, for July 23–24, 2026 [19].
Those two names tell a pharmacist which form is present. They don't show how the substance may affect you.
An FDA panel advises the agency about drugs made for named patients. Its July agenda covered the 503A list, which tells those pharmacies which raw substances are allowed.
BPC-157 and two other substances were also listed. FDA staff had proposed against adding TB-500, and a meeting isn't approval.
The panel can only advise FDA about the 503A list [20]. FDA must make any final TB-500 rule, and no result has been issued or dated.
Why FDA placed the ingredient in safety Category 2
FDA calls TB-500 a small section of thymosin beta-4. On September 29, 2023, it put that ingredient in Category 2, the risk group for drug ingredients that may pose major safety risks [21].
FDA pointed to gaps in safety facts and a possible immune response tied to how the drug enters the body. An immune response means your body may react to the substance as though it were harmful.
Category 1 is a different group that may get a temporary pass during review. FDA marks its page current through April 22, 2026 and places TB-500 in the "Bulk drug substances nominated but withdrawn" table, not Category 2 [20].
FDA hasn't approved TB-500 as a finished drug. A pharmacy's raw-ingredient rules still apply to TB-500; prescribing it does not turn a compounded product into an approved drug [20].
The FDA entry also says which form the warning covers. It names the seven-part piece from thymosin beta-4 as TB-500 [21].
What the meeting can't change without an FDA decision
The TB-500 nomination was withdrawn, and the ingredient is no longer in FDA's present Category 2 table. In FDA's older plan, Category 1 got a temporary pass during review, while Category 2 did not [20].
On January 7, 2025, FDA stopped giving new ingredients the Category 1 or Category 2 labels. It left the old entries in place [20].
The withdrawn nomination does not put TB-500 in Category 1 or grant permission to compound it [20]. A current prescription offer does not resolve that raw-ingredient question.
Talk of a broad early-2026 change or dated "removals" isn't backed by a finished FDA decision [20]. The July 2026 agenda said the ingredient was being considered for the allowed list [19].
That wording marked a discussion, not a new rule, and FDA has published no record of the panel's votes as of September 2026.
What must happen before a pharmacy can make your drug
In the United States, a doctor, or another person who may legally prescribe must examine you before choosing a made-to-order drug [22]. That person must write a valid prescription just for you.
A 503A pharmacy makes one drug for the person named on a prescription; a 503B facility may make larger batches after it registers with FDA [22]. The larger-batch route can't override an ingredient ban.
Your doctor's check may happen by video. A video visit can't turn a barred ingredient into an allowed one or replace a valid prescription [22].
Federal law offers three routes for a raw ingredient: an official drug standards book, use in an approved drug, or FDA's allowed list [22]. The official book is simply a list of accepted drug standards.
FDA's 2023 major-risk listing kept TB-500 off the usual 503A path. The withdrawn TB-500 nomination is outside the present Category 2 table; withdrawal does not put the ingredient in Category 1 or authorize compounding [20].
These are broad legal and medical facts, not advice or an offer. At mypromise.com, Promise Peptides prescribes TB-500 following a licensed U.S. clinician's review, which can end in a refusal. U.S. patients are the only group served, and state rules can limit which treatment is offered. That compounded TB-500 medication has no FDA drug approval. This digest does not take requests or supply medication.
Can normal pharmacy rules supply TB-500 now?
FDA hasn't approved TB-500 as a drug. It put the seven-part piece in Category 2, its warning group for possible major safety risks [21][20], and its page now lists that request as withdrawn. A clinician may consider a TB-500 prescription, but the ingredient rules remain a separate check for the pharmacy [22]; sport rules also ban it.
Which TB-500 rule does a pharmacy check before filling one prescription?
A pharmacy making a drug for one named patient must first confirm that the raw ingredient is allowed [22]. The FDA safety label is part of that check. FDA keeps its safety concerns beside the withdrawn TB-500 nomination [21]; a prescription by itself cannot settle whether an ingredient meets compounding rules.
What does FDA say about TB-500 today?
On September 29, 2023, FDA placed TB-500, the small thymosin beta-4 piece, in Category 2 under its 503A law for medicines made for one named patient because of possible immune reactions and missing safety facts [21]. FDA's page now shows that nomination as withdrawn, and the ingredient was on the agenda of a July 23–24, 2026 FDA meeting; that meeting couldn't change the rule by itself, and FDA has posted no record of its votes [19].
Has FDA approved TB-500 for any illness?
TB-500 has no FDA-approved use in people [21]; a clinician's decision to prescribe it does not change that. The withdrawn raw-ingredient nomination neither authorizes compounding nor establishes drug approval [20].
What may happen when a tested athlete uses TB-500?
The World Anti-Doping Agency sets the drug-test ban for TB-500 and thymosin beta-4 in the matching sport groups, both during and outside a contest [13]. Tests can find the small piece from both people and horses, and racehorse use led to tests for the substance.