[1][2] According to Stereogum, the EP covers the beginning, middle, and end of a relationship in reverse chronological order.

"[4] The second track, "Gomenasai" came from a conversation Kelela had with Nguzunguzu's Asma Maroof about a documentary which discusses black women in popular music for the past 50 years and how they've been discriminated against.

The song is "a narrative of a woman being the dominant person is the bedroom, but also dealing with someone who doesn't necessarily represent what you think of as a bottom.

Dahi played Kelela a version of the instrumental that was originally intended to be on Tinashe's album, but didn't make it.

"[4] According to Kelela, "The High" is the first song she's ever done, "It was when I first got a VoiceLive Touch, which is a piece of gear that allows you to manipulate your vocals by affecting them and looping and being able to do that simultaneously.

"[4] She stated that the EP is a cycle, "starting on a somber note and going through all the phases of excitement and power and loss to come back around again.

The mechanics of dance music might inspire feelings in listeners, but within the genre, overrun with the egos and opinions of "bro-teurs," her emotions are revolutionary.

She is a transparent creator, unafraid of tainting the canvases of her mostly male collaborators with the imperfect, vulnerable contents of her brain and heart.

"[11] Consequence of Sound commented that "Hallucinogen shows Kelela’s remarkable confidence and strength through a fragility and willingness to admit faults and weaknesses.

"[6] Fact said "the theme of pining which was thread throughout her debut mixtape Cut 4 Me is still present here, but more pointed and poetic this time around.

"[13] Now Magazine noted that "Kelela re-teams with many of Cut 4 Me's producers to refine her sound, while simultaneously feeling more fluid, organic and psychedelic – hence the titular nod to the intoxicating effects of love – than its predecessor.

"[8] Spin thought that "Kelela obviously doesn't shy away from wearing her label's signifiers, but on Hallucinogen she transcends them, the same way she outlasted lazy classification into PBR&B in 2013, swimming to the hazy surface of a new kind of future sex/love sounds.