TB-500 FAQ

What is TB-500?

TB-500 is a lab-made chain of seven amino acids. It copies seven links from thymosin beta-4, a protein with forty-three amino acids ^[8]. Those links touch actin, a support that helps cells move. The small peptide is sold for research and animal use, but no use in people has been approved ^[16]. I'd keep that point close as you read.

There still isn't treatment proof.

What do TB and 500 mean in TB-500?

“TB” points to thymosin beta-4, the full protein. “500” is a product and research label for the small lab-made piece. A horse product uses a similar name. Neither is the proper chemical name. When you read a paper, check whether researchers used the small peptide or the full protein ^[8].

A sales label isn't proof for your body.

How might TB-500 work?

The part copied into TB-500 is where thymosin beta-4 touches actin. In thymosin beta-4, that part wraps around one loose actin bit in a 1:1 match. It covers both ends, so the actin can't join a strand too soon. That helps a cell time changes in its shape and movement ^[1]. There is still no human proof that the seven-link peptide does the same ^[12].

The cell idea isn't a proved effect in your body.

How is TB-500 tied to Thymosin Beta-4?

The actin-touching part in TB-500 comes from thymosin beta-4 ^[8]. Thymosin beta-4 has many more links. Most repair studies used the full protein, which weighs about 4963 daltons. They didn't use the small peptide, which weighs about 889 daltons ^[5]. Before trusting a claim, ask which compound the study used.

They aren't the same.

Which amino acids make up TB-500?

Seven amino acids make up TB-500. Proteins are built from such small links. Five names are used because some links repeat. Makers add a minor change to one end ^[8]. The finished peptide weighs near 889 daltons.

Its known parts still don't tell you your result.

How is TB-500 different from full-length Thymosin Beta-4?

Thymosin beta-4 has forty-three amino acids and weighs about 4963 daltons. TB-500 has seven amino acids and weighs about 889 daltons ^[9]. In mice, a lab-made piece from the actin area copied some wound repair seen with thymosin beta-4 ^[7]. The test didn't show that people get the same result or that the small peptide keeps every effect.

A mouse can't answer for you.

What do researchers study TB-500 for?

Researchers have tested thymosin beta-4 in animal tests and lab dishes. They looked at wounds, eyes, hearts, brains, hair, scars, and new blood vessels ^[5][9]. Far less work tested the small peptide. None of these is an approved use in people. To weigh a claim, ask whether it studied someone like you.

Does TB-500 help muscle tears or recovery from exercise?

Proof from people is missing. Thymosin beta-4 helped immature muscle cells move toward hurt muscle in lab work. But a six-month test in weak-muscled mice found more new fibers without more strength or better heart work. In 2026, a review in Sports Medicine called the animal repair signs hopeful but found thin safety facts in people for unapproved peptides such as TB-500 ^[12]. Strength didn't improve in the mice. You don't have a result from people.

Could TB-500 help a tumor grow?

Several cancers contain high levels of thymosin beta-4. Studies tie it to tumors spreading and making new blood vessels ^[9]. Moving cells may help repair tissue. In theory, the same action might help a tumor. This doesn't show that the small peptide causes cancer. But long safety studies in people don't exist ^[12], so nobody has a firm answer for you.

That calls for care but doesn't prove harm.

Is TB-500 banned by WADA in competitive sports?

Yes. WADA bars TB-500 and thymosin beta-4 under its rules for peptides, growth factors, and tissue repair. For those groups, the ban may apply during contests and between contests. Special tests found these compounds in material taken from horses and people. A sports ban isn't the same as an FDA pharmacy rule. One doesn't prove the other.

Your sport's current rules apply to you.

Is TB-500 FDA approved?

No. FDA hasn't approved TB-500, a thymosin beta-4 peptide, for use in people or for any treatment ^[16]. FDA's page marked current on April 22, 2026 no longer shows TB-500 in Category 2. That was a group of raw ingredients denied the usual leeway for pharmacy mixing because of safety concerns. The small peptide now appears in a table for requests that sponsors withdrew ^[16][17]. FDA hasn't explained the withdrawal's meaning for a pharmacy working under Section 503A, the law for patient-specific custom drugs.

A withdrawn request isn't approval for your use.

The drug remains unapproved.

Have any human trials tested TB-500?

No fair trial has tested TB-500 in people. In a Phase 1 safety test, adults were split by chance; some got a placebo, a look-alike with no drug. They tolerated 1260 milligrams of thymosin beta-4 through a vein ^[6]. Eye-drop trials used thymosin beta-4 under the lab name RGN-259 ^[11]. One heart study finished, but that doesn't tell you whether it worked. Another shot study was withdrawn, leaving your question open.

How long might TB-500 take to heal an injury?

No healing time comes from people. Researchers made deep wounds in rat skin. With thymosin beta-4, new skin cover rose 42% by day four and 61% by day seven against salt water. Wounds closed more and had more collagen ^[3]. Rat timing isn't a promise or amount guide for you.

Your wound may heal differently.

Can TB-500 help a tendon or ligament injury?

Animal proof is thin. Thymosin beta-4 helped a rat knee ligament heal. Hurt muscle also releases thymosin beta-4, which draws immature muscle cells toward it ^[9]. No fair study in people has tested the small peptide for a tendon or ligament injury ^[12]. Your tendon isn't a rat's. Advice for your injury needs to come from someone who can examine it.

What did TB-500 heart studies find?

In mice, thymosin beta-4 switched on messages that help cells survive. Researchers closed an artery that fed the heart. More heart cells survived, and the mouse hearts worked better ^[2]. Thymosin beta-4 didn't reduce the same kind of heart damage in pigs. The animal results are mixed, and neither test proves what the small peptide does in people.

Animals can't give you your heart result.

Does TB-500 grow new blood vessels?

Thymosin beta-4 helped blood-vessel cells move and make new vessels ^[14]. New vessels may feed a wound while it heals. They may help a tumor get blood ^[9]. No study shows how the small peptide acts in people. Both the hoped-for wound help and the possible tumor risk matter to you and your doctor.

Did TB-500 protect the brain after a stroke?

The stroke test used thymosin beta-4, not the small peptide. Rats improved after belly shots of 2 and 12 milligrams per kilogram of body weight. The authors' math pointed near 3.75 milligrams per kilogram, an amount they hadn't tested. The 18 milligrams per kilogram amount gave no clear help ^[4]. Rat results don't prove what happens in people.

Those amounts can't guide your stroke care.

Does TB-500 grow hair?

At low lab levels, thymosin beta-4 helped rat and mouse hair grow. It woke young cells beside the hair roots and raised a protein-cutting substance that the lab labeled MMP-2 ^[9]. The test didn't show whether that rise caused the growth. Research in people hasn't proved that the small peptide grows hair. Your question still lacks proof from people.

Does TB-500 reduce swelling?

In animal and cell work, thymosin beta-4 quieted a swelling message labeled IL-8 by the lab. It also helped switch off the swelling response after its work was done ^[13]. The test didn't use TB-500 in people. No study has found that the small peptide reduces swelling in people.

There still isn't proof from people.

What TB-500 side effects are known?

There isn't a fair human safety record for TB-500. In an early safety test called Phase 1, healthy adults tolerated up to 1260 milligrams of thymosin beta-4 through a vein ^[6]. This result doesn't show the small peptide is safe. Concerns include possible tumor and blood-vessel risks ^[9], plus doubt about research-vial contents. A 2026 Sports Medicine review says safety facts in people are scarce and serious harm is possible ^[12].

Without human facts, you can't call the small peptide safe for your body.

How is TB-500 different from BPC-157?

Both are sold as research peptides for tissue repair, but they aren't the same. TB-500 copies the actin-touching part of thymosin beta-4 ^[1]. BPC-157 is a different peptide first linked to stomach fluid and may act another way. FDA hasn't approved either one for people ^[16]. Seeing them offered as a pair doesn't mean a study proved the pair works.

You need proof for your choice.

Did TB-500 help wounds heal?

Wound research mostly used thymosin beta-4. In rats, new skin covered up to 61% more of a wound after seven days. Wounds drew together and held more collagen. Skin cells also moved after 10 trillionths of a gram in a dish ^[3]. Eye drops containing thymosin beta-4, called RGN-259, helped the clear outer eye heal in people ^[11]. Another thymosin beta-4 result still isn't a test of the small peptide.

Those figures can't predict your skin's healing.

Is TB-500 a steroid?

No. TB-500 is a seven-amino-acid lab-made peptide. It isn't a steroid hormone. Steroids are fatty substances built from joined rings and often work by receiving hormone messages inside cells. TB-500 is built differently. It copies a part that touches actin, a support inside cells ^[1]. Sports talk may place it near muscle-building drugs, but the chemistry isn't the same.

You can't call it safe for your body.

Is TB-500 legal?

This answer covers U.S. drug rules and WADA sport rules. FDA hasn't approved TB-500 as a drug ^[16]. FDA now lists the request among those withdrawn by their sponsors and hasn't given pharmacies a clear next step ^[16][17]. WADA bars the small peptide from tested sport. It is sold for research and animal use, not as an approved drug for people. This isn't legal advice for your case.

You need advice from someone who knows your local law.

Can a compounding pharmacy provide TB-500?

In September 2023, FDA put the thymosin beta-4 peptide TB-500 in Category 2 under Section 503A, the law that lets a pharmacy prepare a drug for one named patient. That label meant serious safety concerns and no usual leeway while FDA reviewed it. The current table instead shows a withdrawn request. FDA hasn't told those pharmacies what comes next ^[16][17]. TB-500 appeared on a July 2026 FDA meeting list for review. FDA staff opposed adding it, and the agency hasn't posted a vote record ^[18]. Clinicians can now prescribe TB-500 after reviewing a person's case, but a request may be refused.

A meeting list isn't permission for your pharmacy.

What does FDA now say about pharmacy-made TB-500?

With its September 29, 2023 update, FDA put the thymosin beta-4 peptide TB-500 in Category 2 under Section 503A, the law for drugs prepared only for the patient listed on the prescription. That group got no usual leeway because FDA believed the safety risks were serious. FDA's current page instead shows a withdrawn request and doesn't tell pharmacies what follows ^[16]. TB-500 has no approved treatment use ^[16]. An FDA advice group discussed it on July 23-24, 2026. By September 2026, FDA had posted no decision or vote record ^[17][18].

The withdrawn entry can't fill in FDA's missing decision. You can't fill that gap with your own guess.