Yes, Peaches Geldof has been known to take drugs.
She was recorded in a Daily Mail newspaper sting, telling her drug dealer that she needed Valium for the come down of another drug she was taking (most likely cocaine).
Some people suspect it was heroin that killed her. There's a full story here: //entertainment.blurtit.com/3982004/how-did-peaches-geldof-die
At the moment it's still too early to know how Peaches Geldof died though!