At the time, he said he wanted to continue to use his seat in the Riksdag to "push my pet issue and increase awareness. To develop more concrete measures to help young alcoholics and drug addicts."
But Petzäll was forcibly committed into care last Monday to prevent an overdose after he was taken to a Gothenburg-area hospital by ambulance, the Aftonbladet newspaper reported.
Petzäll nevertheless appealed the initial decision to have him committed, which was taken by the local social services board in accordance with Sweden's Care of Alcoholics, Drug Abusers and Abusers of Volatile Solvents Act (Lagen om vård åt missbrukare – LVM).
However, the Gothenburg Administrative Court (Förvaltningsrätten) ruled on Friday that Petzäll should be forced into institutional care, despite his protests that he was aware of his addiction problems and was working to deal with them.
According to Aftonbladet, the 23-year-old MP has struggled with addiction to Valium and methadone, a drug often used to treat heroine addicts.
Petzäll first took a time-out from his political activities in February after a drunken outburst in Trelleborg in southern Sweden resulted in him spending the night in jail to sober up.
According to Swedish law, a person can be committed involuntarily following a report to social services from a doctor, relative, or social worker.
The law is applied if the addicts' physical or mental health is deemed to be at risk, if they are in danger of destroying their lives, or if they are thought to have the capacity to seriously injure themselves or others.
The initial institutionalisation can last up to six months, at which point the case is reviewed.