Prescription-only compounds, explained
Quite a few compounds people ask about — melatonin at pharmacological doses, THC-based medicines, metformin, rapamycin, and others studied for longevity — are prescription-only medicines (POM)in the UK. That's not bureaucracy for its own sake: these substances carry real risk profiles, need dose management, and require a clinician to weigh benefit against harm for youspecifically. Here's how legal access actually works, and where the evidence stands.
Why a compound ends up prescription-only
The MHRA classifies medicines along a ladder: prescription-only (POM), pharmacy-only (P, sold after a pharmacist conversation), and general sale (GSL, open shelf). A compound lands higher on that ladder when misuse or unsupervised use carries meaningful risk — interactions, organ toxicity, dependence, or narrow dose windows. The higher the ladder, the more evidence the regulator demands before anyone can sell it to the public for a given purpose.
The legal route: consultation first, prescription second
For a prescription-only compound, the lawful path in the UK runs through a doctor or qualified prescriber — increasingly via regulated online clinics and telehealth services. Clinics that prescribe remotely must be CQC-registered (Care Quality Commission), and prescribers operate under GMC (or equivalent regulator) rules, including for off-label prescribing where the clinical justification is documented and the patient consents with eyes open. If a service will hand you a prescription-only medicine with no meaningful consultation, that's a red flag — lawful prescribers check history, interactions, and follow-up.
A word on naproxen and “longevity drugs”
You may have seen headlines that naproxen extends lifespan — that comes from the US Interventions Testing Program (2024), which reported roughly 14% median lifespan extension in male mice. It is not evidence for humans. Long-term naproxen use in people carries established risks — gastrointestinal bleeding, kidney strain, and cardiovascular events — which is why it isn't (and shouldn't be) sold as an over-the-counter “longevity microdose”. The same logic applies to other repurposed-drug longevity ideas doing the rounds: promising in animals, unproven and non-trivially risky in humans. Anyone selling prescription drugs to the public with anti-ageing claims is operating outside the law, and regulators on both sides of the Atlantic have been acting on it.
What Works for Us does — and doesn't do
We are the evidence layer. We track what the published science and our community's real-world outcomes say about compounds — supplements, health foods, and medicines alike. We don't sell medicines, don't prescribe, and don't take positions on whether any prescription is right for you. For compounds that are prescription-only, our pages say so, plainly, and point you here. For everything available over the counter, we show where it's typically sold — and our ratings are never influenced by it.
This page is general information, not medical or legal advice. Regulations change — check MHRA guidance or talk to a clinician for your own situation.