The main rationale for prescribing hydrocodone with acetaminophen is that a decreased dose of opioid is required. The two medications work in concert on different receptors, but do not have a synergistic effect. Hydrocodone and acetaminophen both have hepatotoxic effects; hydrocodone does not decrease the hepatotoxic effects of the acetaminophen. By requiring a lower dose of opioid, the patient may have less constipation and somnolence associated with the medication, but this is a byproduct, not the main rationale for prescribing hydrocodone with acetaminophen.