On the Showtime series, Jackie (Falco) has become addicted to prescription medication. Falco told New York Magazine that the character is close to "either getting over this [addiction] or dying from it".
Falco said: "At the heart of the whole show is the nature of addiction, which is something that I really do understand. Not just in my own experience but I've known and loved many addicts.
"There is no judgment calls when it comes to getting what you need, there is no gradation of things you won't do. If what stands between you and your fix is something that six months ago was untouchable, it doesn't matter."
Falco hinted that Jackie could sink to a new low in the show's upcoming fourth season.
"Most addicts wind up going beyond each and every one of those things they said they won't do," she claimed. "So it mostly means to me that she's closer to either getting over this or dying from it."
Falco was recently nominated for a Critics' Choice Television Award for her performance as Jackie.
The third season finale of Nurse Jackie is scheduled to air on June 20 on Showtime.
> Nurse Jackie star: 'Coop isn't malicious'