Prepare your questions
What is known about the risks?
The main finding is uncertainty. A missing study is not a reassuring side-effect list.
In the US, medicines are reviewed by the Food and Drug Administration, known as the FDA.
What is missing, and what is a possible concern
There is no measured human safety record
The FDA review looked for evidence on TB-500 itself.
- As of September 2026, the FDA has found no study in which people received TB-500, so its side effects in people remain unknown.
- FDA reviewers also found no TB-500 animal studies on harm from brief or repeated use, pregnancy, or cancer. They found none on damage to genes, the instructions inside cells that guide how the body grows and works.
- The short human safety record for full-length thymosin beta-4 cannot establish safety for TB-500.
The immune concern is a risk assessment
The immune system is the body's defence system. It can react to a substance it treats as foreign.
- The FDA warns that injected TB-500 may cause the body's defence system to react. Clumping or unwanted material in the product may increase that risk.
- The FDA found no study that measures how often such reactions occur with TB-500.
- That concern is a possible risk, not a measured rate of harm.
Read the batch records with their limits
A purity sheet is a limited answer
A certificate of analysis is a test sheet describing a sample. Ask which checks were actually done.
- The TB-500 test sheet described by FDA reviewers did not check poisons made by bacteria, clumped peptide, or unwanted material.
- For an injection, the FDA treats checks for germs, poisons made by bacteria, and stray particles as key safety factors.
- Ask for the ingredient name and the records for the batch, meaning the group of bottles made together. Ask which safety checks were done on that batch and what the records cannot tell you.