What is a potential side effect of Fentanyl?

Fentanyl is a potent synthetic opioid analgesic commonly used for pain management, particularly in acute and chronic pain scenarios. One of the significant side effects associated with fentanyl and other opioids is respiratory depression. This occurs because fentanyl acts on the central nervous system, particularly on the brain's opioid receptors, which regulate the body’s breathing response. At higher doses or in sensitive individuals, fentanyl can suppress the respiratory drive, leading to inadequate ventilation and oxygenation of the body. This side effect warrants careful monitoring of patients receiving fentanyl, especially during administration or when adjusting dosages, to ensure they maintain adequate respiratory function.

The other options, while they can be associated with general opioid use, are not primary side effects of fentanyl. Hypertension, hypokalemia, and diarrhea are not typical effects that one would expect specifically from fentanyl use, making respiratory depression the most relevant and critical side effect to be aware of when administering this medication.