Before seeking care with a thymosin fragment
Looking for a TB-500 provider?
Start with what is known. Then put your questions on paper before choosing care.
The fragment’s evidence gap
The FDA, the U.S. Food and Drug Administration, has not approved TB-500 for any use, as of September 2026.
In its review checked in September 2026, FDA found no published study in which people received TB-500.
Begin with the name
What TB-500 actually is
TB-500 is a peptide made in a lab—a short chain formed from the building blocks of proteins.
It copies a small part of thymosin beta-4, a longer protein found in the body.
The full protein and TB-500 are different substances.
The studies in people reviewed in September 2026 used the whole thymosin beta-4 protein, not TB-500.
Those results do not establish that TB-500 helps people heal.
Keep your concern in view
Your notes are not sent anywhere. Print the page to keep a copy.
Approval and access
Can a pharmacy make it?
Compounding means making a medicine to order, often in a pharmacy.
For a medicine made for one named patient with a prescription, the U.S. law is called section 503A.
HHS plans to hold off on enforcement over TB-500 prepared for one patient’s prescription by state-licensed pharmacies or licensed physicians meeting the terms of its October 30, 2026 draft.
These are legal conditions for using an ingredient, not the results of a lab safety test.
Under section 503A, an ingredient must meet one of these conditions, as of September 2026:
If an official ingredient standard exists, the ingredient must meet that standard and the rules for making the medicine.
If no such standard exists, the ingredient must be part of an FDA-approved medicine.
If neither applies, the ingredient must be on FDA’s list of ingredients allowed under section 503A.
As of September 2026, TB-500 has no official ingredient standard, is not part of an FDA-approved medicine, and is not on that list.
Even an ingredient that meets a condition must come from a maker that has sent its details to FDA.
It must also come with a valid document reporting checks of its contents.
HHS proposes in its October 30, 2026 draft to forgo enforcement for TB-500 prescription compounding that meets its requirements.
Ask the doctor to name the law that allows any proposed treatment and show you the source. Ask about other care for your concern.
If someone proposes a different way to get TB-500, ask them to name the law that allows that way.
What happened to the request to use TB-500?
The group that asked FDA to let pharmacies use TB-500 took its request back.
FDA calls this “nominated but withdrawn.”
The entry for TB-500 appears beneath that heading on FDA’s page, current as of April 22, 2026.
FDA still lists its safety concerns about TB-500 there.
As of September 2026, TB-500 remains without FDA approval even though the request was taken back.
HHS proposes an enforcement pause for TB-500 prescription compounding that meets the requirements in its October 30, 2026 draft.
Keep the rule with the answer
Leave space for uncertainty
Unknown does not mean safe
As of September 2026, TB-500’s side effects in people remain unknown.
FDA’s review checked in September 2026 found no published studies or reports of individual patients receiving TB-500.
The review also found no animal studies checking TB-500’s safety.
FDA’s review warns of a possible immune reaction, where the body treats an injected substance as an invader.
As of September 2026, TB-500 has no medicine information checked by FDA on taking it with other medicines.
It also has no FDA-checked information for pregnancy, breastfeeding or use in children.
Make room for an honest answer
Ask the doctor what is still unknown and what other care options you can discuss.
Does your sport test for banned substances?
Under the 2026 World Anti-Doping Agency rules, TB-500 is barred during competition and between events.
Bring the sport’s rules into the conversation with the doctor.
Read the world sport listTake questions into the visit
Compare the answers. Write down whether the visit is in person, by phone or by video. Include the studies you were shown and the full cost.