Is my website hacked?

I have noticed through Google webmaster tools that the main keywords of my website belongs to what I would call “an online pill store”. I have nothing to do with it, and certainly it is affecting negatively my SEO.

How can I remove such informations? do I have to search into the database for such keywords? I wouldn’t like to delete something important.
I am also noticing that nothing is wrong with the looks or the code generated with the website, but the infamous keywords results are there.

try for yourself: google the word casagli
and some spam keywords that you may think of and see what you get.