From the Guidelines

It is not recommended to combine hydromorphone 3.5mg IV and norco 15mg due to the increased risk of respiratory depression and overdose.

The combination of these two potent opioids can lead to excessive sedation, respiratory depression, and potentially life-threatening complications 1.
Instead, consider alternative pain management strategies that prioritize patient safety, such as using a single opioid medication at a lower dose or exploring non-opioid pain management options 1.
If pain management requires opioid use, close monitoring of the patient's respiratory status and vital signs is essential 1.

Use a single opioid medication at a lower dose to minimize the risk of respiratory depression and overdose 1.
Explore non-opioid pain management options, such as non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen, which may be effective for managing pain without the risks associated with opioids 1.
Consider using alternative routes of administration, such as oral or transdermal, which may be safer and more effective than intravenous administration 1.

Close monitoring of the patient's respiratory status and vital signs is essential when using opioids for pain management 1.
Regular assessment of the patient's pain and functional status can help guide adjustments to the treatment plan and minimize the risk of adverse effects 1.
Patient education and discussion before starting opioid therapy are critical to ensure that patients understand the risks and benefits of opioid use and can make informed decisions about their care 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

The effect of hydromorphone 3.5mg IV plus Norco (hydrocodone and acetaminophen) 15mg is not directly addressed in the provided studies 2, 3, 4, 5, 6.
However, the studies provide information on the pharmacology and clinical applications of hydromorphone, which can be used to infer potential effects.
Hydromorphone is a potent opioid analgesic, approximately 5 times as potent as morphine when given orally and 8.5 times as potent as morphine when given intravenously 5.
The combination of hydromorphone with other opioids, such as hydrocodone, may increase the risk of adverse effects, such as constipation, nausea, and sedation 2, 4, 6.
The efficacy of hydromorphone for acute and chronic pain has been demonstrated in several studies, but the evidence is limited by the small number of studies and the heterogeneity of the study designs 3, 4, 6.

The use of hydromorphone and Norco together may increase the risk of opioid-related adverse effects, such as respiratory depression, constipation, and nausea 2, 4, 6.
The combination of hydromorphone with acetaminophen, a component of Norco, may also increase the risk of liver toxicity, particularly at high doses or with prolonged use 6.
The studies do not provide direct evidence on the safety and efficacy of the specific combination of hydromorphone 3.5mg IV and Norco 15mg, and therefore, caution should be exercised when using this combination 2, 3, 4, 5, 6.