Ah, that would then be:-
Δεν μπορείτε να έχετε καθόλου. Πιστεύω ότι ξέρετε για τις παρενέργειες.
Καθόλου and κανένα both mean 'any' but I think my Greek word is correct in the context of the sentence. Otherwise you left out "you cannot" and used an incorrect conjugation elsewhere. It's a bleeding difficult language as so many single English words are said with different words in Greek and the endings of Greek verbs and nouns will change to give specific meaning to a statement. I struggle to get off first base with it all and that is why I like to use it here and when 'talking' with Cypriot friends on Facebook as I need the practice!! Mrs B gets a bit bored with me walking into a room and making a statement like "Remember when we were told that the word for ... was ...., well I've just discovered it should be ........" "Knock yourself out there" is her favourite reply!