Ozzy Osbourne says nicotine is the hardest drug he ever had to give up.The rocker, who has battled alcoholism and illegal substance addictions throughout his life, admits he continued to smoke while wearing nicotine patches, even though it made him ill. He said in an interview with Guitar World magazine: "They're all a **** to kick, but I'd have to say cigarettes were the toughest."I used to cover my whole body with nicotine patches. I looked like a f***ing mummy. And I'd still smoke! Then my heart would start beating like crazy and I'd break out in sweats. But one day I just said, 'Enough of this s**t.' And I quit, just like that."Ozzy, 58, recently confessed he was out of control for years on tour and would get as high as he could on anything he could get his hands on. He said: "With me, it was the longer the bus journey, the more I could get f***ed up. I would drink until I dropped, do cocaine, LSD, anything."You wouldn't want to imagine me on LSD. There were horses in a field. They were talking to me!"I knew I was in trouble when I couldn't get offstage quick enough to get whatever variety of s**t I was tipping down me."