By her own admission, Drew Barrymore had begun drinking and smoking cigarettes by the age of 9, smoked marijuana at 10 and started using cocaine at 12. It took two stints in rehab in her early teens before she found sobriety.
There was a time when many people figured actor Robert Downey Jr. for dead, such were his struggles with addiction. Drug arrests for cocaine, heroin and marijuana and various stints in rehab had him dealing with his addiction in a very public way. Today, the "Iron Man" actor has been sober since his last stint in rehab in 2001.
Aerosmith was one of the hardest-partying rock and roll bands ever, and lead singer Steven Tyler was no exception. Addicted to heroin and cocaine, he's said he used drugs with every member of the group before going to rehab in 1986. He later relapsed, but has been clean since completing rehab for painkiller abuse in 2009.
World-renowned guitarist Eric Clapton's problems with heroin have been widely reported. During 1971's Concert for Bangladesh, he passed out, was revived and continued his performance. With the help of former addict Pete Townsend, he kicked heroin a few years later and later gave up drinking in the 1980s. In 1998, he founded the Crossroads Centre on Antigua, a medical facility for recovering substance abusers.
Rocker Ozzy Osbourne's struggles with alcohol and drug addiction were so bad that he was fired from Black Sabbath in 1979. His drinking and drug use continued throughout the 1980s, with him crediting his then-manager and later wife, Sharon, for eventually helping him get clean.
Rapper Eminem has often spoken about his addiction to prescription drugs, including Vicodin, Ambien, Valium and Methadone. He eventually had to cancel the European leg of his Anger Management Tour in August 2005 and go into rehab for his addiction to Ambien.
Growing up as a wild child, Angelina Jolie began experimenting with drugs at an early age. By the age of 20, she confessed to doing "just about every drug possible, cocaine, ecstasy, LSD and, my favorite, heroin." She credited her first husband, British actor Jonny Lee Miller, her co-star in 1996's "Hackers," for helping her give up drugs.
Throughout his career, singer-songwriter Elton John has struggled with addictions to alcohol and cocaine. In 1975, he survived an overdose during "Elton Week" in Los Angeles. It wasn't until 1990 that he got sober.
Red Hot Chili Peppers lead singer Anthony Kiedis began using marijuana and cocaine at the age of 12 with his father, later trying heroin accidentally for the first time at age 14. After a heroin overdose killed close friend and bandmate Hillel Slovak in 1988, he vowed never to use again. He's been in and out of rehab since, relapsing twice, but has claimed to have been clean since December 2000.
David Bowie suffered from a cocaine addiction in the 1970s. By his own admission, cocaine use twisted his sanity and he overdosed several times during 1976. It wasn't until the late 1970s that he was able to kick his addiction.
Early in his career, Samuel L. Jackson developed addictions to alcohol and cocaine. After seeing the effects of his addiction, his family entered him in a New York rehab clinic, with his first post-rehab role being that of a crack cocaine addict in Spike Lee's 1991 movie "Jungle Fever." Jackson has called the role cathartic for him.
"Home Improvement" star Tim Allen's struggles growing up have been well documented. Allen spent more than two years in prison after pleading guilty to a cocaine-trafficking charge in 1978, but it took a 1997 DUI arrest that sent him to rehab to get clean and sober.
Black Eyed Peas singer Fergie developed an addiction to crystal methamphetamine while part of the girl band Wild Orchid in the 1990s. "It was the hardest boyfriend I ever had to break up with," she told Time magazine in September 2006. The singer had stated in several interviews that she used hypnotherapy to help overcome her addiction.
Alice Cooper once called himself "probably the most functional alcoholic ever," but that was before he embraced Christianity in the mid-1980s and stopped drinking for good. He's since taken to counseling other rock musicians with addiction problems.
In the late 1990s, Nine Inch Nails front man Trent Reznor turned to alcohol and drugs to deal with depression, social anxiety disorder and the death of his grandmother, who raised him. In 2001, he successfully completed rehab for addiction to alcohol and cocaine.
British comedian Russell Brand is a former heroin addict and a recovering alcoholic. He has abstained from drug use since 2002 and has cited his practice of transcendental meditation as a significant factor in his recovery.
In his memoir, horror master Stephen King tells of a 1987 intervention by family and friends in which they dumped evidence of his addictions from the trash, including beer cans, cocaine, Xanax, Valium, NyQuil and marijuana, on the rug in front of him. King wrote that he sought help and quit all forms of drugs and alcohol and has remained sober since.
Supermodel Naomi Campbell entered rehab in 1999 after a five-year addiction to cocaine. In a 2005 interview with ABC's Diane Sawyer, she referred to cocaine as a "very nasty drug."
After several stints in rehab for an addiction to prescription painkillers, Kelly Osbourne says she has been clean since 2009. "I knew I'd been given another chance at my life, at my career, at happiness. I wanted to grab it," she wrote in her 2009 autobiography "Fierce."
Mary Tyler Moore first went public with her battle with alcoholism in her 1995 book "After All." She sought treatment in the 1980s at the Betty Ford Center after keeping her problem hidden from family and friends.
"One Day at a Time" actress Mackenzie Phillips first tried cocaine at age 11 with her father and was fired from the show over her drug abuse. Phillips, who later aired out her issues with a stint on "Celebrity Rehab" and a tell-all memoir, says she has been sober since a 2008 arrest for drug possession.
Actor Dennis Quaid has spoken several times about his past abuse of cocaine when he first came to Hollywood in the 1970s, telling Larry King in 2002 that "I saw myself being dead in about five years if I didn't stop."
Actress Jamie Lee Curtis is a recovering alcoholic who was once addicted to painkillers she began using after a routine cosmetic surgical procedure. She became sober in 1999 and has said that recovery is the greatest achievement of her life.
Country singer Keith Urban checked himself into the Betty Ford Center a few months after marrying fellow Aussie Nicole Kidman in 2006 for treatment of an alcohol addiction. He has remained sober since.
Ben Affleck entered alcohol rehab in 2001, with a spokesman for the actor saying that "Ben is a self-aware and smart man who had decided that a fuller life awaits him without alcohol."
"Sex and the City" star Kristin Davis told Health magazine in 2008 that she was a recovering alcoholic who found sobriety at age 22. "I've never hid it, but I've been sober the whole time I've been famous, so it wasn't like I had to go to rehab publicly," Davis said at the time.
Throughout the 1980s, Boy George struggled with a heroin addiction, but addictions to other drugs would also follow. After getting clean and enjoying 16 years of sobriety, he relapsed in 2003 and eventually found himself in trouble with the law, including serving four months in prison. He now claims more than four years of sobriety.
The Velvet Underground's Lou Reed became famous for his debauched lifestyle, at one point quipping that he tried to quit drugs by drinking. One of his most famous songs is simply titled "Heroin." But by the 1980s he'd cleaned up his act. He even appeared in a 1989 "Rock Against Drugs" PSA stating, "Drugs. I stopped. You shouldn't start."
In the fall of 2013, Lady Gaga admitted to being addicted to many substances at various points in her life, including marijuana, but said she got to the point where she knew she "had to stop" because she was jeopardizing her health.