Vicodin may make you drowsy, less alert, or unable to function well physically. Do not drive a car, operate machinery, or perform any other potentially dangerous activities until you know how Vicodin affects you.
Use caution in taking Vicodin if you have a head injury. Narcotics tend to increase the pressure of the fluid within the skull, and this effect may be exaggerated by head injuries. Side effects of narcotics can interfere in the treatment of people with head injuries.
Use Vicodin with caution if you have a severe liver or kidney disorder, an underactive thyroid gland, Addison's disease (a disease of the adrenal glands), an enlarged prostate, or urethral stricture (narrowing of the tube carrying urine from the bladder).
Older adults and those in a weakened condition should be careful using Vicodin, since it contains a narcotic.
Narcotics such as Vicodin may interfere with the diagnosis and treatment of people with abdominal conditions.
Hydrocodone suppresses the cough reflex; therefore, be careful using Vicodin after an operation or if you have a lung disease.
High doses of hydrocodone may produce slowed breathing; if you are sensitive to Vicodin, you are more likely to experience this effect.