Released on February 3, 2003, as the second single from their third album, More Than You Think You Are (2002), it was written by Matchbox Twenty lead singer Rob Thomas.

"Unwell" was nominated for a Grammy Award in 2004 for Best Pop Performance by a Duo or Group with Vocal.

Directed by Meiert Avis, the music video predominantly features Thomas seeing various odd occurrences throughout, all the while singing along to the song.

The other band members only appear in cameos, notably when Thomas boards a subway and they are seen in the background.

One of the reasons Thomas picked Avis to direct is because his concept for the video was the closest thing to an acid trip out of every other idea.