The Boomtown Rats frontman insists he was always keen to avoid heroin and stick to cocaine during his years as a rock wildman, but there was one occasion when he unintentionally consumed the deadly drug.
Geldof reveals a fellow star - who he has declined to name - was desperately trying to woo his then-wife Yates, and the mystery man spiked the I Don't Like Mondays hitmaker to increase his chances with the blonde, but she gave him the brush-off anyway.
Geldof tells Britain's Guardian newspaper, "I never did anything stronger (than cocaine), though I took heroin once by mistake."
Yates and Geldof split in 1995 over her affair with Inxs frontman Michael Hutchence. She died from a heroin overdose in 2000.