Regeneron Chief Executive Leonard Schleifer said he welcomed the FDA ensuring that drugmakers don’t exaggerate their products’ benefits or play down side effects. Regeneron, whose drugs include the eczema treatment Dupixent, sometimes gets frustrated with the claims made in competitors’ advertising.

A senior official in the Trump administration told CNN enforcement by the FDA in the past few years has not been stringent enough, with only one enforcement letter sent in 2023 and none issued in the...