Nauseous or nauseated

"Nausea" began to be used to mean "afftected by nausea, feeling sick to one's stomach" shortly after WW2. Some people object to this, but it is established in general prose. There is no ambiguity because "nausea" patterns differently depending on its meaning. When "nauseous" means "sick" it follows a linking verb and a personal subject: "I feel nauseous."

When "nauseous" means "causing nausea" it is often an attributive adjective and the subject is not personal: "This is nauseous medicine."

There's more to it; Merriam-Webster's Dictionary of English Usage has 3 pages on the subject.

Sorry, when I wrote "nausea began..." and "nausea patterns differently..." I should have written "nauseous."

My dictionary says both are acceptable.

This exact issue was mentioned in "Never Been Kissed" with Drew Barrymore. Her character (correctly) pointed out that "nauseated" is indeed correct. But if everyone says it wrong, is it still wrong?

"Nauseated" indicates that one has completed arrived at the state. "Nauseous" indicates that one is on one's way.