Quick answers from the study record
TB-500 questions with straight answers
Each answer starts with what happened. When people weren't tested, you'll see that at once.
What does TB-500 copy?
Scientists made TB-500 to study one small protein part. It copies parts 17–23 of thymosin beta-4. The full protein is a 43-amino-acid chain [1]. Amino acids are small building blocks that make proteins. The copy holds actin inside cells. Labs and animal teams use it. No human use has approval. Your body makes the full protein, but it doesn't make the copy. Keep that split beside each claim you read.
What does the name TB-500 mean?
The letters "TB" come from thymosin beta-4. That is the full thymosin beta-4 protein's name. "TB-500" is a trade and animal-research name for the small lab copy [1]. The number is only a sales label. It tells you nothing about how the substance works. Other product names may point to the same copy.
What did researchers hope TB-500 might repair?
Researchers studied skin wounds, hurt muscle, and ligaments. They also tested hearts and brains. Some work used animals. Other work used dish-grown cells [5][7]. The strongest results belong to full thymosin beta-4. People haven't had a fair trial proving that the small copy works [4]. Check the form before trusting any claim.
How might TB-500 move cells?
TB-500 copies an actin-gripping section [1]. Actin gives cells support and lets them move. Full thymosin beta-4 grips one free bit of actin. That may affect cell movement, swelling, and new vessels [5]. Researchers haven't shown that the small copy does this in people. A thymosin beta-4 result isn't proof of a benefit for you.
Why isn't TB-500 a steroid?
TB-500 is a peptide, not a steroid [1]. Peptides are short chains built from amino acids. Amino acids are protein building blocks. This chain has seven and comes from thymosin beta-4. Steroids have a different make-up and can carry hormone messages. TB-500 holds actin instead. The two aren't related types of substance.
What TB-500 side effects remain untested?
Good human safety facts for TB-500 are scarce. Tumor growth is the main study worry. Full thymosin beta-4 helps cells move and vessels grow [12]. A Phase 1 safety test found that people tolerated full thymosin beta-4 by vein. Amounts reached 1260 milligrams [4]. The small copy wasn't tested in daily use. A lab product's label may misstate what is inside or how much. Ask your doctor what the missing test means for you.
Why does TB-500 raise a cancer concern?
Researchers found much thymosin beta-4 in several cancers. Cancer cells may travel with help from the protein. New vessels may also feed a tumor. Those same acts can help wounds heal [12]. In cancer, they might help spread. Human research hasn't tied the small copy to cancer. This is a possible risk, not a verdict. It remains the main study concern.
What did TB-500 hair claims come from?
Small amounts of thymosin beta-4 made hair grow in rats and mice [5]. The full protein woke cells near the base of hair roots. Those cells can make new working cells. The animals didn't get the small copy. TB-500 hasn't been shown to grow hair in people [4]. You can't carry the animal result to your own scalp.
Why can't anyone call TB-500 safe yet?
No fair human safety trial has tested TB-500 [4]. The nearby facts are mixed. In Phase 1, people received up to 1260 milligrams through a vein and tolerated the full protein [4]. Mice with weak muscles grew more fibers. Their strength didn't rise [8]. Cancer work raises concern about new vessels [12]. Those facts still don't answer whether the small copy is safe.
Which human tests used TB-500 itself?
No finished, fair trial in people exists for TB-500 [4]. Human teams studied full thymosin beta-4. A Phase 1 vein test found people tolerated up to 1260 milligrams [4]. Other teams put thymosin beta-4 in eye drops. A planned shot study for sudden stroke was later withdrawn [10]. None of these used the small copy.
Why hasn't FDA approved TB-500?
FDA hasn't approved TB-500 to treat any illness [16]. Labs and animal researchers use it. Human study facts apply to full thymosin beta-4, not the small copy [4]. FDA once put the small copy in Category 2, its high-concern group [16]. The TB-500 legal status and pharmacy access page explains what changed later.
What does the dated TB-500 legal record say?
TB-500 isn't an FDA-approved human drug. Lab suppliers sell it for research. World sports rules bar it in tested events. Some nations treat it as a prescription drug [16][4]. FDA marked its page current on April 22, 2026. The page says the TB-500 request was withdrawn. It no longer lists the drug in Category 2. FDA hadn't said if a patient-specific pharmacy could use it [16][17]. This is general information, not legal advice.