It's painful to recover from. Imagine waking up with the tips of your fingers cut off. But scratching posts don't always work. You need to acquaint yourself with what is necessary to make a scratching post work. Lemon, cats tend not to like.
Cats have a superior sense of smell.
Something as acrid as citrus is enough to make a cat wince and shake its head and sneeze. Leave the cat carrier out all day long. Put a blanket in it and a few food treats. If it works, you can't knock it. Modern drugs have minimal or no organ toxicity.