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Regulatory hub · UK status

TB-500: UK regulatory status

Also known as: Thymosin Beta-4 fragment, TB4-Frag

Last reviewed . Editorial commentary, not legal advice.

MHRA: No UK marketing authorisation Prohibited (WADA S2, peptide hormones and growth factors)
AI-friendly summary · TB-500

TB-500 is not a controlled drug under the Misuse of Drugs Act 1971 and is not scheduled under the Psychoactive Substances Act 2016. It holds no UK marketing authorisation as a medicine. WADA lists Thymosin Beta-4 and fragments under S2 of the Prohibited List.

Misuse of Drugs Act 1971

TB-500 does not appear on any schedule of the Misuse of Drugs Act 1971. Possession in the UK is not criminalised under controlled-drugs law.

Psychoactive Substances Act 2016

TB-500 is not covered by the Psychoactive Substances Act 2016.

MHRA and medicines classification

TB-500 holds no UK marketing authorisation. UK research peptide retailers list it under "research use only" framing. Therapeutic claims trigger unlicensed medicinal product enforcement risk.

See: MHRA medicines classification (POM, P, GSL).

WADA Prohibited List position

TB-500 (Thymosin Beta-4 and its synthetic fragments) sits under WADA S2 (peptide hormones, growth factors and related substances). Prohibited at all times for tested athletes.

See: WADA Prohibited List and peptides.

ASA advertising framing

UK sellers cannot describe TB-500 as a healing, recovery or anti-inflammatory product in paid advertising. Editorial commentary on the preclinical literature is permitted.

See: ASA rules on weight-loss advertising.

Primary sources

When in doubt about your specific position, consult MHRA directly via the MHRA contact page or seek qualified UK medicines law advice.

Frequently asked questions

Is TB-500 legal in the UK?
TB-500 is not a controlled drug under the Misuse of Drugs Act 1971 and is not scheduled under the Psychoactive Substances Act 2016. It holds no UK marketing authorisation as a medicine. WADA lists Thymosin Beta-4 and fragments under S2 of the Prohibited List.
What is the MHRA position on TB-500?
TB-500 holds no UK marketing authorisation. UK research peptide retailers list it under "research use only" framing. Therapeutic claims trigger unlicensed medicinal product enforcement risk.
Is TB-500 on the WADA Prohibited List?
TB-500 (Thymosin Beta-4 and its synthetic fragments) sits under WADA S2 (peptide hormones, growth factors and related substances). Prohibited at all times for tested athletes.
What can UK sellers say about TB-500 in adverts?
UK sellers cannot describe TB-500 as a healing, recovery or anti-inflammatory product in paid advertising. Editorial commentary on the preclinical literature is permitted.

Related: TB-500 editorial entry · UK regulatory hub.

Reviewed by Oliver Mackman, editorial director · last reviewed 2026-05-22T12:00:00.000Z