Lindsay Lohan
Actress Lindsay Lohan arrives at the 2010 MTV Movie Awards in Los Angeles June 6, 2010 REUTERS/DANNY MOLOSHOK

A lot of successful celebrities at certain points in their lives have been involved in drugs. A notable few even publicly announced that they were abusing substances to relieve stress or overcome their stage fears. An unfortunate few also became so addicted, eventually to their failure in the industry or ultimately their death.

Here are some Hollywood stars who admitted getting hooked.

1. Miley Cyrus

Billy Ray Cyrus' daughter revealed that she was a regular marijuana user in a unique way. During her acceptance speech at the 2013 MTV Video Music Awards, the pop singer lit a joint and said to the audience, "You know, I couldn't fit this award in my bag, but I did find this." She took a few puffs before getting off the stage. Fortunately, she was smoking weed in Amsterdam, which was legal in the area. She later tweeted, "Sometimes in life you gotta just decide not to give a [expletive]."

2. Lady Gaga

Lady Gaga also showed to the world that she smoked marijuana. In 2012, she lit a joint during a performance in Amsterdam. She further admitted smoking as many as 15 joints per day to help numb the pain and discomfort while she was recuperating from a hip surgery. Although she said that she is currently sober, she added that she still smokes weed a few nights a month.

3. Amanda Bynes

Bynes has been involved in a number of scandals due to her marijuana smoking and excessive alcohol drinking. She was arrested for possession of the drug and admitted in a rehabilitation center in Malibu. Later on, the Nickelodeon star was diagnosed with schizophrenia.

4. Justin Bieber

Justin was discovered to be using drugs after pictures of him surfaced. The photos featured him in a house party where he was smoking a weed joint. He was busted a few times in different countries for possession of drugs.

5. Lindsay Lohan

Another Disney child star, Lindsay frequently checked in and out of rehabilitation centeres for marijuana abuse. She has been arrested for driving under the influence of alcohol or drugs and was involved in various scandals due to her extreme habits.

Not all users saw their careers go downhill. Bieber, for one, is still up in the "successful" list, although fans really hope he would start cleaning up his act. Of the Hollywood stars that admitted doing drugs, we can't help but give props to Robert Downey Jr., who was once (or several times?) institutionalized for drug abuse. Downey has since gotten over his bad boy days and moved into being bad-ass as the irreplaceable Tony Stark.