Receiving mixed reviews from critics, the album debuted at No. 128 on the Billboard 200 and No. 2 on the Heatseekers Chart, and as of 30 January 2009, the album has sold 1,000,000 copies worldwide and 500,000 copies in the US. It's the first album released through Trustkill Records to be officially certified gold by the RIAA.
The album received mixed reviews from the critics, however many fans consider The Poison to be the band's strongest album. Corey Apar of Allmusic awarded the album 3 stars out of 5, stating "Overall, The Poison is a well-produced, solid effort – but seeing as they're now trying to take over American hearts, it would be nice to see future attempts to distinguish themselves more from the new-school pack."Sputnikmusic also gave the album a 3 out of 5 with the explanation that it is "fun to listen to, and the guitar work sure is nice. The vocals are good as well, as main singer has a good voice, melodic and screamed, well supported by the screaming of the bassist." Music Emissions said the album contained very catchy songs, with clean and fast guitar sounds, and "an undertone of pop" which fits with the drumming. Despite its positive points, the reviewer said that the album would not attract people from outside the metalcore subgenre.
Stylus Magazine gave the album a C− (below average) and said that The Poison album appeared to be made for provincial 15-year-olds to get violent with each other. The reviewer noted two songs that were indicative of the band's "A-game": "The Poison" and "Suffocating Under Words of Sorrow (What Can I Do)". Punk News said that the album was "drab", leaving the reviewer bored with the slow pace, and frustrated that the screaming loud passages were delivered without a sense of anger or attitude.