Johansson got his start musically by making his own remixes of tracks by Skinny Puppy and posting them online under the name Triptamine, in 1998. In 2001, Johansson finished recording an album called Ileus that he self-released as a CDR under the name Tarmvred, with remixing by Hedberg, credited as Digidroid. Around the same time, Johansson came into contact with Nicolas Chevreux who invited him to sign with a new label Chevreux was starting called Ad Noiseam. Hedberg continued working with Johansson until Hedberg was listed as a member of Tarmvred in 2003 on Viva 6581. Tarmvred has recorded primarily on the German Ad Noiseam label, although its latest release, the vinyl-only e.p. Tintorama, is on Low Res Records, based in Detroit, Michigan. A new full-length album is due to be released in autumn, 2008, as stated on Tarmvred's MySpace page.
Tarmvred's music has an experimental, electronic style, with heavy beats, a barrage of irregular percussion, distortion, and sparse use of melody. Only one brief stanza of clearly sung lyrics appear in all of their work, by guest vocalist Gertrud Polonyi; it appears on track 5 of Subfusc, as well as on the track "Mourning" on Onomatopoeic (apparently the same recording of the lyrics). Heavily distorted lyrics appear on a few other tracks, never more than briefly. Their tracks sometimes wander between rhythmic and chaotic, and have a wide variety of motives that continue falling away or appearing throughout the track. Tarmvred recorded much of Viva 6581 using a MOS 6581 sound chip, featured in early-80's computers such as the Commodore 64.