Customs checks
GOV.UK says anything posted or couriered from another country goes through customs. Customs checks that it is not banned or restricted, and that the right tax and duty have been paid. The parcel or courier company takes it through customs.
Some goods cannot be brought into the UK at all, and controlled drugs are on that list. Whether a particular product is allowed is a legal question that depends on what it is and how it is presented.
Tax and duty
Seizures
If the rules are not followed, goods can be seized by Border Force or HMRC, and the person may be fined or prosecuted. GOV.UK sets out how to ask for seized goods back or ask for a court hearing. Seized goods are destroyed or sold if nothing is done.
Who you are dealing with
An overseas business will not be on the UK Companies House register, so you cannot check it there. Citizens Advice says your rights may be different when you buy from a company based outside the UK, and points people to the UK International Consumer Centre for help.
Whether a product counts as a medicine in the UK is decided by how it is presented and what it does, not by where it is shipped from. The MHRA sets out how that is judged.
Getting proper advice
This page describes how the system works. It is not legal advice. For questions about importing a specific product, speak to a solicitor.
Educational information only. Nothing here is medical advice, dosing guidance or a recommendation to use any substance. Research peptides are not approved medicines and are not for human or animal consumption. Speak to a qualified professional and follow the law where you are.