A dance-pop and techno-pop song with elements of South Asian music, "Toxic" features varied instrumentation, such as drums, synthesizers and surf guitar.

"Toxic" has been covered by artists such as Local H, Mark Ronson, A Static Lullaby, Reece Mastin and Ingrid Michaelson, and in the TV series Glee.

[14] The hook of "Toxic" samples a portion of "Tere Mere Beech Mein", from the soundtrack of the 1981 Bollywood film Ek Duuje Ke Liye.

[citation needed] NME described the song as presenting "piercing strings, hip-hop beats, eastern flavour and a dangerous escapade with temptation.

"[18] According to the official sheet music on Music-Notes, "Toxic" is set in the key of C minor, and follows a fast tempo of 143 beats per minute, but the pre-chorus is based on the C Dorian mode.

[14] Christy Lemire of Associated Press stated it was one of Spears' greatest hits and deemed it "insanely catchy", remarking that the chorus alone "makes you want to forgive the Alias wannabe video that accompanies the song.

"[27] Stephen Thomas Erlewine of Allmusic called it along with "Showdown", "irresistible ear candy in what is surely Britney's most ambitious, adventurous album to date".

"[32] Joan Anderman of The Boston Globe named it "a well-titled cascade of frantic, mechanized glissandos and dreadful canned strings that buries the album's coolest (only?)

[36] Pitchfork named "Toxic" the third-best single of 2004, writing that "finally, [Spears] just acted like an adult, rather than constantly reminding us she wasn't a girl anymore".

Kahn stated he was "not sure what I was thinking about when she told me about that scene, maybe those intros to James Bond movies, but every video needs an iconic image to remember, and that's it."

Spears also shot scenes in which she had to dance through a hallway of imaginary lasers in front of a green screen, something that Kahn deemed as "incredible to watch".

[63] The music video begins with an open shot of an airplane flying and preceded by three menacing dark birds, referencing the works of Hong Kong director John Woo.

[58][65] Spears then appears, completely re-dressed and with red hair, standing in a futuristic Paris, similar to the film Blade Runner (1982),[58] and takes a ride on the back of a Ducati 999, driven by a shirtless male (Tyson Beckford).

She wears a tight black catsuit and sports red hair, inspired by the character of Sydney Bristow from the television series Alias.

[61] As they speed past a woman, the draft from the motorcycle lifts up her dress, a homage to the iconic Marilyn Monroe scene in the film The Seven Year Itch (1955).

[58] Jennifer Vineyard of MTV compared the video to Justin Timberlake's "Cry Me a River", saying that "Where her real-life ex just stalked his cheating lover in his clip, [...] Spears takes a more lethal approach.

[73] Amy Schriefer of NPR noted that in the video, Spears was no longer trying to break away from her 1990s teen pop image and style; she was comfortable and having fun, not trying to generate any type of calculated controversy.

Jillian Mapes of Billboard wrote that Spears "proved that she comes in every flavor [...] But the one role that stays constant through the dance-heavy clip: Sultry maneater.

While the choreography was deemed as "erotic", Corey Moss of MTV commented that some of the effect was lost due to Spears's lip-synching and a stagehand fixing a prop during the song.

[85] After an introduction in which she briefly appeared on a large video screen, Spears took the stage standing on top of a hotel bus, wearing a tight black catsuit.

[84] MTV UK commented, "OK, so she doesn't so much sing than mime along with Toxic, [...] But what do you expect when she's simultaneously performing a vigorous dance routine, ascending moving staircases and descending fireman poles?".

After "Do Somethin'", in which Spears wore a hot pink bra, a white fur coat, and a jean skirt, she ended the set with "Toxic", with four female dancers in a Shakira-like style.

The song was also streamed live along with "Work Bitch" from Spears' final Britney: Piece of Me show date on December 31, 2017, on ABC's Dick Clark's New Year's Rockin' Eve to a record audience of 25.6 million.

"Toxic" is a swirl of spaced-out glam-disco kicks, spy-movie strings, surf-guitar twang, a beat that should wear a warning, and Britney's distinctive slithery drawl.

Jess Harvell commented that Spears had great pop instincts and that "Toxic" showed how "Britney always had more individualist pep than her peers, important when you're dealing with steamroller productions from the mind of Max Martin.

[106] Evan Sawdey of PopMatters commented that "Toxic" is a rare kind of song that transcends genre boundaries, and added that Spears delivered the track that defined her legacy.

[145] In 2005, American folk group Chapin Sisters recorded an acoustic cover of "Toxic", which was featured on PerezHilton.com and became one of the most requested songs of the year in KCRW.

In January 2022, the mashup was completed and officially released through Sony Music Entertainment under the title "Toxic Pony", being credited to Altégo, Spears and Ginuwine.

[172] In the 2005 episode "The End of the World" of the TV show Doctor Who, the character of Cassandra unveils an ancient jukebox that reproduced "Toxic" as an example of "a traditional ballad" from about 5 billion years prior.

"[176] "Toxic" is featured on British soap opera Emmerdale in July 2021 when Meena Jutla (Paige Sandhu) dances to the song after she murders Leanna Cavanagh (Mimi Slinger).