How to calculate retail media ROAS for CHC products in the UK

Why standard formulas aren't enough -- and how to build a measurement framework your CFO will approve.

Introduction: pharmaceutical retail media in the UK, a rapidly accelerating market

Retail media has become the most dynamic growth lever in pharmaceutical e-commerce in the UK. On Amazon.co.uk, Boots, and LloydsPharmacy, advertising investments from consumer healthcare (CHC) brands are growing significantly year on year. Sponsored Products, Sponsored Brands and programmatic display formats are multiplying, and players like Criteo Commerce Media now fuel the media ecosystems of Pharmacy2U and other European e-pharmacies.

But this acceleration poses a concrete problem for performance marketing teams and e-commerce managers: how do you truly measure the return on investment of these expenditures?

The answer seems obvious: you calculate ROAS (Return on Ad Spend). You divide the revenue generated by the amount invested in advertising. And yet, in the pharmaceutical sector, this simplistic formula misleads more often than it guides. Purchase cycles are longer, brand halo effects are real, customer journeys traverse multiple retailers, and regulatory constraints from the MHRA and CMA add additional layers of complexity.

This article proposes a comprehensive methodological framework for calculating, interpreting and exploiting retail media ROAS in the specific context of CHC products in the UK. It's aimed at performance marketing teams, finance-oriented e-commerce managers, and anyone who must justify their media investments to a demanding finance department.