But she denied persistent rumours that she is suffering from eating disorders in the interview with ABC's Diane Sawyer, for the network's Primetime programme.
"
My business is sex, drugs, rock and roll - but as you get older and wiser you stop a lot of the kid stuff
"
Whitney Houston
"I am not sick. Let's get that straight. I am not sick, OK?," she said.
Houston, 39, addressed a wide range of questions about her private life, including her stormy marriage to singer Bobby Brown.
He was arrested last month in Atlanta and charged with drug and traffic offences.
Referring to Houston's own drug abuse, Sawyer asked her: "Is it alcohol? Is it marijuana? Is it cocaine? Is it pills?"
Houston replied: "It has been at times."
"All?" asked Sawyer, to which Houston replied: "At times. Uh-hm."
She added: "I don't like to think of myself addicted... I had a bad habit which can be broken. I'm not gonna tell you I'm somebody's junkie.
"My business is sex, drugs, rock and roll. You know? My friends, we have a good time. But as you get older and you get wiser - you stop a lot of the kid stuff.
"Trust me. I partied my tail off. You get to a point where... the party's over."
Houston, who was promoting her forthcoming album Just Whitney, said her religious faith would see her through tough times.
"I'm on the right path... I'm a very prayerful person, even in the midst of the trouble, of the battle," she said.
Questions about Houston's health and behaviour have featured in US gossip columns for years.
In 2000 she was abruptly dropped from the performance line-up of the Academy Awards broadcast.
In the same year she was arrested at an airport for marijuana possession, but the charges were later dropped.
At Michael Jackson's tribute concert last year she appeared gaunt, fuelling rumours about her health.
But she vehemently denied that her thinness was the result of an eating disorder, such as anorexia or bulimia.
"No way," she said. "I've always been a thin girl. I'm not going to be fat, ever. Let's get that straight."
She said at times of emotional stress her eating habits were "awful".
The full interview will be broadcast by ABC in the US on Wednesday evening.