Which opioid does not release histamine?

Which opioid does not release histamine?

• A. Morphine
• B. Meperidine
• C. Fentanyl
• D. Hydromorphone

Answer: (C)

Histamine release with opioids comes from direct mast cell degranulation, which causes itching, flushing, and sometimes hypotension. Some opioids trigger this more than others. Morphine is a well-known trigger of histamine release; meperidine can do this as well. Hydromorphone may cause some histamine release, but to a lesser extent. Fentanyl, by contrast, has minimal effect on mast cells and therefore rarely causes histamine-mediated side effects. That’s why fentanyl is the best answer for an opioid that does not release histamine.

Histamine release with opioids comes from direct mast cell degranulation, which causes itching, flushing, and sometimes hypotension. Some opioids trigger this more than others. Morphine is a well-known trigger of histamine release; meperidine can do this as well. Hydromorphone may cause some histamine release, but to a lesser extent. Fentanyl, by contrast, has minimal effect on mast cells and therefore rarely causes histamine-mediated side effects. That’s why fentanyl is the best answer for an opioid that does not release histamine.