In addition to Kiedis and Flea, the group originally featured guitarist Hillel Slovak and drummer Jack Irons. However, Slovak died of a heroin overdose in 1988, resulting in Irons resigning. Irons was replaced briefly by former Dead Kennedys drummer D. H. Peligro before the band found a permanent replacement in Smith, while Slovak was replaced by up-and-coming guitarist Frusciante. This lineup recorded the band's fourth and fifth albums, Mother's Milk (1989) and Blood Sugar Sex Magik (1991).
Blood Sugar Sex Magik was a critical success and sold over twelve million copies. However, Frusciante grew uncomfortable with the band's success, leaving abruptly in 1992. Kiedis, Flea, and Smith employed Dave Navarro of Jane's Addiction for their subsequent album, One Hot Minute (1995). However, it failed to match the critical acclaim of Blood Sugar Sex Magik and sold fewer than half the copies of its predecessor. Shortly afterwards, Navarro was fired from the band due to creative differences.
Frusciante, during his time away from the band in 1998, completed rehabilitation, rejoining the band at Flea's request. The reunited foursome returned to the studio to record Californication (1999), which went on to sell fifteen million units worldwide, becoming their most successful album to date. It was followed three years later with By the Way (2002), which continued their success. In 2006, the group released the double album Stadium Arcadium. The band has won six Grammy Awards. They have sold over fifty million albums worldwide, have had seven singles in the Top 40 of the Billboard Hot 100 (including three singles in the Top 10), have had five #1 singles on the Mainstream Rock charts, and a record eleven #1 singles on the Modern Rock charts.