Nicole Richie wasn't allowed to go 'cold turkey' in rehab.The reality TV star checked into rehab when she was just a teenager after her addictions to cocaine, pills and heroin spiralled out of control.However, staff at the center were so concerned that her drug-dependent body would go into shock if they took her off the substances, they had to slowly wean her off. Nicole revealed to Marie Claire magazine: "Anyone who goes to rehab will say that they don't remember their first week or two, because your body just goes through the shock of coming off whatever you were on. They didn't want me to quit cold turkey because I could have had a seizure, so they gave me medication to come off it."Nicole, who is rumored to be pregnant with boyfriend Joel Madden's baby,says she became addicted to heroin the very first time she tried it. She added: "I can remember the first time I tried it as a teenager - there was a lot of vomiting. But your body becomes physically dependent on it right away."