Medical Definition of Fentanyl

Reviewed on 8/26/2022

Fentanyl is a synthetic narcotic (opioid) drug that was developed to control pain but has become a widespread drug of abuse. Pharmaceutical fentanyl is available as lozenges, tablets, or patches by prescription to control severe pain, typically in cancer patients. Fentanyl is 80 to 100 times stronger than morphine and about 50 times more potent than heroin. As a drug of abuse, fentanyl is illegally produced and often added to heroin, cocaine, or other drugs; this is sometimes done without the purchaser's knowledge. This can lead to death by overdose.

Signs and symptoms of opioid overdose include

  • limpness of the body,
  • pale or clammy face,
  • a bluish color to the nails or lips,
  • vomiting,
  • inability to awaken or be roused, and
  • slowed breathing and heartbeat.

Anyone with suspected opioid overdose should receive emergency medical attention.



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United States. Centers for Disease Control and Prevention. "Fentanyl." June 1, 2022. <>.