I found this: "The most common reported side effect of Subutex and Suboxone include: cold or flu-like symptoms, headaches, sweating, sleeping difficulties, naus

I found this: "The most common reported side effect of Subutex and Suboxone include: cold or flu-like symptoms, headaches, sweating, sleeping difficulties, nausea, mood swings. Like other opioids Subutex and Suboxone have been associated with respiratory depression (difficulty breathing) especially when combined with other depressants." Sounds like a hangover.