Joni Mitchell says she was "never much of a druggie."
The 71-year-old singer admits she dated a lot of guys who used drugs, but was rarely tempted to indulge.
She said: "I never was much of a druggie. Cigarettes and coffee - that's my poison."
But the 'Big Yellow Taxi' hitmaker believes the drug was one of the things that led to her split from British singer-songwriter Graham Nash in 1969 after they had a passionate affair.
She explained: "Cocaine just puts a barrier up. Where Graham and I had been a real couple, very close, suddenly there was this barrier. People were more secretive about drugs back then."
Joni also thinks their relationship was doomed to fail.
She said: "Graham and I fell in love, and he got sick and I Florence-Nightingaled him back to health. We were a good couple. I cooked for Graham, but the trouble was he's from Manchester, and he liked gray, wrinkled peas from cans. And I like fresh peas from the market. I like to cook - I got quite zaftig, actually. But when he started doing coke, he had no appetite."
Meanwhile, Joni insists she didn't leave David Crosby for Graham because they were never together.
She told Vanity Fair magazine: "David Crosby and I were never a couple. We spent time together in Florida and he was off drugs and very enjoyable company at the time. We rode bicycles through Coconut Grove and went boating. But David's appetites were for young harem girls who would wait on him. I would not be a servant girl."