Thymosin Beta-4

Also known as

Other names:

• TB-500
• TB4

Therapeutic Goods Administration (TGA) approval

Thymosin Beta-4 is not approved by the TGA.

World Anti-Doping Code Prohibited List 2026

Thymosin Beta-4 is listed under S2.3 Growth Factors and Growth Factor Modulators.

What is it?

Thymosin Beta-4 is a peptide hormone that is naturally produced within the human body.

This peptide consists of 43 amino acids linked together to form a chain.

It plays an important role in the immune system and has numerous biological activities.

These include:

• anti-inflammatory actions
• stimulating the growth of new blood vessels
• regulating cellular lifespan and;
• promoting tissue growth

Uses

Thymosin Beta-4 is not approved for human use anywhere in the world.

Animal experiments and clinical trials have investigated its therapeutic use for various conditions, including in:

• cardiovascular conditions
• eye injuries
• promoting wound healing and;
• treatment of colon cancer

It is considered a growth factor which effects the growth of muscles, tendons, ligaments and blood vessels.

Therefore, the administration of Thymosin Beta-4 is banned in sport at all times, by the World Anti-Doping Agency.

How does it work?

Primarily, Thymosin Beta-4 helps cells grow and repair themselves by supplying critical building materials to the cell.

This allows cells to grow, adapt to change and stabilise cell shape.

It also works through numerous other mechanisms and is therefore considered a ‘moonlighting’ peptide.

This is a phenomenon where a substance has more than one function within the body. 

These pathways are not fully understood.

Adverse Health Effects and Risk

Thymosin Beta-4 can extend the lifespan and promote the growth of cells. 

Unfortunately, this mechanism is indiscriminate, and there is serious concern that it increases the spread and growth of cancer cells.

Before a drug can be approved by the TGA, a strict process is followed which investigates the drug's safety and effectiveness over an extended period.

Sufficient short and long-term studies evaluating Thymosin Beta-4 have not been conducted and therefore its safety profile remains largely unknown.

Thymosin Beta-4 is therefore not approved by the TGA or any other regulatory agency and is not considered suitable for human use.

What if an athlete has been prescribed Thymosin Beta-4 for a medical condition?

A Therapeutic Use Exemption (TUE) would not be granted for the use of thymosin beta 4 in any medical condition.

Click the below link for more information regarding TUEs:
Therapeutic Use Exemption (TUE)