This medicine should not be taken with the Alcohol or CNS depressant as it very dangerous from health point of view. Hydrocodone may be habit forming. Patients should stop using as soon as the prescribed period got over.
The generally reported adverse reactions are faintness, wooziness, sedation, queasiness and vomiting. These effects seem to be more prominent in those who are working while in people who stays idle may experience severe reactions.
Other adverse reaction might include different reactions on the central nervous system (mood swings, fear, lethargy etc), Gastrointestinal System (constipation), Respiratory System (respiratory depression), Special Senses (hearing can be damaged) and Dermatological (allergic reactions like rashes etc)
As for the contraindications, this medicine should never be used by those patients who have a record of exhibition to hypersensitivity to hydrocodone or acetaminophen. As patients who are known to be hypersensitive to any opioids, may exhibit cross-sensitivity to hydrocodone.
Reaction of Vicodin is related to how Hydrocodone and acetaminophen works in the body.