Why Physician Loyalty Lies With MSLs, Not Companies

Published 4 August 2026

Author(s): Richard Meyer

One of the least discussed questions in Medical Affairs is also one of the most important: When a Medical Science Liaison (MSL) changes companies, what happens to the physician relationship?

For organizations investing millions in MSL teams, the answer has major implications for hiring, retention, launch planning, and territory transitions. The common assumption is that KOL relationships belong to the company. The reality is far more nuanced.

The evidence—and decades of experience across Medical Affairs—suggests that physician thought leaders are often loyal to the individual MSL before they are loyal to the pharmaceutical company.