It is very common to see people use these two words incorrectly. They’ll say nauseous when they really mean to say nauseated. This is understandable, given how similar they are in scope and meaning. This is the same reason why differentiating between poisonous and venomous can be so challenging.
So, what is the difference between nauseous and nauseated?
Nauseous = Cause Nausea
If you were to describe something as nauseous, that would mean that it causes nausea. (In case you didn’t already know, nausea is “a feeling of sickness with an inclination to vomit.”) Here’s an example:
Nauseous gases may be used in biological and chemical warfare.
Here’s another example:
Meant to induce vomiting, emetics are a nauseous substance.
Nauseated = Experience Nausea
What if you’re the one who is feeling sick to the stomach? If that’s the case, then nauseated is the word that you want. To be nauseated is to feel, become, or experience nausea.
I must have food poisoning from that restaurant. I feel nauseated.
In the strictest sense, certain grammar gurus will tell you that it is incorrect to say, “I feel nauseous,” though this usage is increasingly common. Language is inherently fluid and dynamic, changing all the time, so saying that you feel nauseous is becoming increasingly accepted.
Similar Word Pairs Are Confusing
When words have the same basic root and they have similar meanings, it can be very easy to confuse the two. Even if they are spelled completely differently but used within the same sphere, as would be the case with disinfectant and antiseptic, it is easy to mistakenly use one when you really mean to use the other.
Do you have a suggestion for a future Grammar 101 topic? Feel free to let me know through the comment form at the bottom of this post.