Singer Fergie
Singer Fergie poses at the eighth annual amfAR Gala Los Angeles in Beverly Hills, California, U.S., October 13, 2017. Reuters

Singer Fergie says she suffered from symptoms of psychosis and dementia due to her drug addiction to methamphetamine, commonly known as crystal meth.

"At my lowest point, I was (suffering from) chemically-induced psychosis and dementia," Fergie told i newspaper, reports dailymail.co.uk.

"I was basically hallucinating on a daily basis. It took a year after getting off that particular drug for the chemicals in my brain to settle so that I actually stopped seeing things," she added.

Reflecting on the intense consequences of the drug, she said: "I'd just be sitting there, seeing a random bee or a bunny."

In September, Fergie had announced a split from husband Josh Duhamel after eight years of marriage.

On the difficulty of juggling work and separation struggles, Fergie said:: "I've just released my first solo album in 11 years, and I'm out promoting it. So there's really a lot going on. That's why we wanted to find our footing with our separation before we announced it publicly -- to make sure we really got it together for our kid."

They have a son named Axl, who was born in 2013.