Image: 4 panels organized in a rectangle following a sequential order like a comic strip. The first panel is of a man with a very serious face stating, “Hey man, got any diphenhydramine?” The second panel is a grainy picture of the actor Tony Stark with a slightly inquisitive face and saying, “What’s that?” The third panel is an identical copy of the first image and saying, “Benadryl the allergy medicine.” The fourth and final panel is a grainy picture of Tony Stark rolling his eyes and taking a deep breath.
Tell that to the copyright lawyers
People have lost trademark rights because it’s too ubiquitous.
Aspirin was literally the brand name by Bayer but lost it.
Fun fact, Aspirin is still registered to Bayer in most of Europe