Summary
The United Kingdom regulates medicines for human use under the Human Medicines Regulations 2012 (SI 2012/1916). Three features of that instrument decide where any of the compounds in this knowledge base sits: the definition of a medicinal product, the requirement for a marketing authorisation, and the classification of an authorised product as prescription-only, pharmacy or general sale 123. Cosmetic products follow a separate regime, assimilated Regulation (EC) No 1223/2009 4. This page describes those instruments and the two registers used to establish UK status. It states what the sources say and does not address the lawfulness of any particular supply.
What counts as a medicinal product
Regulation 2 defines a medicinal product as "any substance or combination of substances presented as having properties of preventing or treating disease in human beings", or any substance that may be used by or administered to human beings with a view to "restoring, correcting or modifying a physiological function by exerting a pharmacological, immunological or metabolic action", or to making a medical diagnosis 1. The definition is therefore reached both by presentation and by function, and it does not depend on the form a substance is supplied in.
The requirement for authorisation
Regulation 46 opens Part 4 of the instrument. It provides that "a person may not sell or supply, or offer to sell or supply, an unauthorised medicinal product", and that a person may not sell or supply a medicinal product otherwise than in accordance with the terms of a UK marketing authorisation, a certificate of registration, a traditional herbal registration or an Article 126a authorisation 2. A further paragraph addresses possession where the person knows or has reasonable cause to believe the product is intended to be sold or supplied to another person within the United Kingdom or the European Economic Area 2.
Part 10 of the Regulations sets out exceptions. Regulation 167 disapplies the regulation 46 prohibitions for a "special medicinal product" supplied in response to an unsolicited order, manufactured to the specification of a named prescriber, for a patient for whose treatment that prescriber is directly responsible, subject to conditions including that no advertisement relating to the product is published and that records of manufacture are kept 5.
Prescription-only status
Regulation 62 requires a UK marketing authorisation or parallel import licence to include a term that the product is available "only on prescription", "only from a pharmacy", or "on general sale" 3. In making that determination the licensing authority must have regard to the maximum single dose, the maximum daily dose, the strength of the product, its pharmaceutical form, its packaging and other relevant circumstances of use 3. Prescription-only status is mandatory where the licensing authority considers the product likely to present a direct or indirect danger to human health if used without medical supervision, frequently and widely used incorrectly with the same consequence, or to contain substances whose activity or side effects require further investigation 3. Regulation 214 then provides that a person may not sell or supply a prescription only medicine except in accordance with a prescription given by an appropriate practitioner 6.
One compound in this knowledge base has a UK schedule entry of its own. The Medicines (Products Other Than Veterinary Drugs) (Prescription Only) Amendment Order 1993 (SI 1993/1890), made on 23 July 1993 and in force from 23 August 1993, inserted "Sermorelin" into Part I of Schedule 1 to the 1983 Prescription Only Order 7. That entry shows sermorelin was regulated as a prescription-only medicine ingredient in 1993; the existence, holder and dates of any UK product licence were not verified from any register 78.
Unlicensed medicines
MHRA guidance states that "unlicensed medicines do not have a marketing authorisation in the UK and may not have been assessed by the MHRA", and that regulation 167 allows unlicensed medicines to be supplied when there are no licensed available medicines that can meet the needs of individual patients, those needs being clinical and determined by the responsible prescriber 9. The guidance describes "specials" as products specially manufactured or imported for the treatment of an individual patient after being ordered by a doctor, dentist, nurse independent prescriber, pharmacist independent prescriber or supplementary prescriber 9.
MHRA has published a position on one compound covered here. On 24 October 2025 it stated that retatrutide "is GLP-1 medicine in clinical development, which has not been approved for UK use" and that, outside authorised clinical trials, products claiming to contain it "are likely to be illegal" 10. A further MHRA release of 29 May 2026 records the seizure of unlicensed weight-loss medicines "including retatrutide and tirzepatide" at a production facility near Northampton 11. By contrast, the semaglutide and tirzepatide products themselves are authorised: MHRA announced the tirzepatide weight-management indication on 8 November 2023 and the four-dose pen presentation on 25 January 2024 1213.
Cosmetics on the GB market
Cosmetic products made available on the GB market are governed by assimilated Regulation (EC) No 1223/2009 together with the Cosmetic Products Enforcement Regulations 2013 14. Guidance from the Office for Product Safety and Standards, last updated 29 June 2026, records that a UK-established Responsible Person and a Cosmetic Product Safety Report signed by a qualified assessor are required, that products are notified through the Submit Cosmetic Product Notification service, and that Annex 2 lists prohibited ingredients while Annexes 3 to 6 list restricted or permitted-only substances 14. The full-text XML of the Regulation on legislation.gov.uk, with a metadata modified date of 19 August 2026, was searched on 21 September 2026: "tripeptide" occurs zero times, so copper tripeptide-1 is not named in Annexes II to VI as published there 4. Absence from an annex is not an authorisation 14.
The two UK registers, and how "no record found" was established
MHRA Products is the agency's public register of medicine documents. Its own description states that it holds the leaflets provided with medicines, the description of a medicinal product's properties and the conditions attached to its use, and "scientific assessment reports called a Public Assessment Report (PAR) available for new marketing authorisations granted after 30 October 2005" 15. It also records that, following implementation of the Windsor Framework on 1 January 2025, existing Great Britain marketing authorisations were converted to UK-wide authorisations with their PLGB prefixes unchanged 15.
The electronic medicines compendium is a separate service. It describes itself as containing information about medicines licensed for use in the UK, with more than 14,000 documents "all of which have been checked and approved by either the UK or European government agencies which license medicines", namely MHRA and EMA, and it is managed and owned by Datapharm Ltd 16. It holds Summaries of Product Characteristics, Patient Information Leaflets, Risk Minimisation Materials and letters to healthcare professionals 16.
Negative UK findings in this knowledge base were established by searching both services and recording the exact response. MHRA Products returned "There are no search results for tesamorelin", and likewise for egrifta, while a control search for somatropin in the same session returned 609 documents 17; the eMC returned no results for tesamorelin 18. The same pattern was followed for ipamorelin 1920, sermorelin 821, retatrutide 22 and thymosin 23. For CJC-1295 and BPC-157 the active-substance index was read instead: the letter C index, with 375 entries, contains no CJC-1295 entry, and the letter B index contains no entry for BPC-157 or bepecin 2425. Each of these is a dated absence from a named register on the date checked, and nothing more.