From the Guidelines
If you are allergic to morphine, it is not recommended to take Norco (hydrocodone/acetaminophen) due to the risk of cross-reactivity between the two opioid medications. According to the study 1, people with morphine allergies do not necessarily have allergies to fentanyl, but there is no mention of hydrocodone or Norco specifically. However, considering the chemical relationship between hydrocodone and morphine, it is reasonable to assume a potential risk of cross-reactivity. The study 1 suggests that fentanyl is a better option for acute moderate to severe pain due to its quicker onset of action and higher potency compared to morphine.
When considering alternative pain management options, the study 1 recommends non-COX specific NSAIDs (e.g., ibuprofen) over codeine-acetaminophen combinations for mild-moderate acute pain. Additionally, COX-2 specific NSAIDs (e.g., celecoxib) are recommended over codeine-acetaminophen combinations due to their safer side effect profile and longer time to re-medication.
Some key points to consider:
- True opioid allergies are rare, and what many people experience as "allergies" are actually side effects like nausea, itching, or respiratory depression.
- If you've had a genuine allergic reaction to morphine (such as hives, swelling, difficulty breathing, or anaphylaxis), you should avoid Norco and consult with your healthcare provider about alternative pain management options.
- Always inform all healthcare providers about your morphine allergy to ensure your safety.
- Your doctor might recommend non-opioid pain relievers like NSAIDs (ibuprofen, naproxen), acetaminophen alone, or other classes of pain medications that don't have cross-reactivity with opioids.
From the FDA Drug Label
CONTRAINDICATIONS Hydrocodone bitartrate and acetaminophen tablets are contraindicated in patients with: • Hypersensitivity to hydrocodone or acetaminophen (e.g., anaphylaxis) [see WARNINGS, ADVERSE REACTIONS] The FDA drug label does not answer the question.
From the Research
Opioid Allergy and Cross-Reactivity
- The risk of IgE-mediated reactions (IMRs) caused by opioids is low in patients with historical IMRs to opioids 2.
- Opioid allergy documentations may propagate alert fatigue and unwarranted prescribing changes 2.
- A retrospective study found no cross-reactivity among any of the opioid drug classes, resulting in 100% re-exposure tolerance rates 3.
- The removal of erroneous opioid allergy labels has a unique importance in the population with acute or chronic pain 4.
Norco and Morphine Allergy
- There is no direct evidence on the safety of Norco in patients allergic to morphine.
- However, studies suggest that opioid allergy cross-reactivity is low, and many patients with historical opioid allergies can tolerate subsequent opioid exposure 2, 3.
- The current approach to patients with pseudo-allergy to opioids is switching to an alternative opioid with less histamine release 4.
- Norco, which contains hydrocodone, may be an alternative option for patients allergic to morphine, but this should be determined on a case-by-case basis.
Clinical Implications
- Clinicians should carefully evaluate patients with reported opioid allergies and consider the possibility of pseudo-allergy or intolerance 2, 4.
- Drug provocation testing (DPT) is the gold standard for diagnosis of opioid allergy, but it is underutilized 4.
- Basophil activation testing (BAT) may be a useful tool for evaluating opioid allergy, but further studies are needed 4.