Iosu lived his entire life in the city of Santurce (Basque Country).

During his childhood enjoyed listening to The Kinks, The Rolling Stones, The Who and then The Clash and Sex Pistols, also he was a great fan of football soccer.

Iosu would be the band's principal songwriter with occasional contributions from Juanma Suárez.

In early 1991, he left the band due to health problems, and was absent from the Eskorbuto Mexico Tour, replaced by Iñaki "Gato".

In 1991, Iosu began a treatment to quit heroin, as he had become very weak after years of addiction.