Produced by Stargate, the song was released as the second single from the album on November 21, 2005, and received favorable reviews from music critics.

Ne-Yo met Norwegian production team Stargate, consisting of Mikkel S. Eriksen and Tor Erik Hermansen, in a hallway at Sony Music Studios on West 54th Street, New York City after the duo had settled there in the early 2005.

"So Sick" centers on a character, who is tired of hearing love songs playing on the radio, as they remind him of his last relationship and breakup.

[4] A review from Contactmusic.com echoed the latter's comment, saying that his vocal rendition is "stunning", while complimenting the Stargate production, defining it as a "melodic masterpiece".

[1] Two music videos were shot for the song, the discarded version featured an urban imagery different to the winter-snow scenario of the original one.

The official remix was produced by Trackmasters and features rap vocals by LL Cool J and sampled Michael Jackson's song "Human Nature".

In 2020, Australian rapper The Kid Laroi released a reworking of the song called "Need You Most (So Sick)", from his debut mixtape, F*ck Love.