Executives have apparently met with the likes of Holly Willoughby and Gino D'Acampo and advised them not to advertise brands in which they have a vested interest on screen.
TV bosses have also given Lorraine fashion expert Mark Heyes a warning after he promoted clothes from Debenhams while being paid as the store's brand ambassador.
"There was a change in the Ofcom ruling with regards to undue prominence and product placement in TV. When there are changes we chat to talent and agents about them," an ITV source told The Mirror.
"In the past Holly has worn a number of her own dresses from the brand Very and Gino often wears bright watches which are on camera a lot, so we have to look at things like this now to make sure we don't do anything wrong."
The source added: "It is important to ITV that there is no favouritism for any brand on Lorraine and the clothes being shown should be the best ones, regardless of what store they come from."
An ITV spokesman insisted that Heyes's outside role didn't affect editorial decisions on the show.
"ITV ensures that all of its talent are aware of and comply with the Ofcom code on product placement and undue prominence. This is an ongoing dialogue," he said.