Vicodin (hydrocodone/paracetamol) consists of acetaminophen, which is often used in nonprescription medication aimed at reliving pain and fever, as well as cough. This ingredient comes with serious side effects such as liver disease and nausea. Vicodin is also based on hydrocodone, which acts on the parts of the brain responsible for how we experience pain. Vicodin is prescribed as a pain reliever and caution should be taken if you have liver problems.