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Fentanyl Side Effects

Fentanyl can cause side effects similar to those of other opioid drugs, including heroin, OxyContin, or morphine. However, since fentanyl is between 50 and 100 times more potent than morphine, the side effects may be more intense, set in faster, or last longer.

Side Effects of Fentanyl

General, opioid-like side effects from fentanyl use – which may include those that occur due to prescription use – are:

  • Drowsiness or fatigue
  • Confusion
  • Trouble concentrating
  • Tightness in the throat
  • Stiff or rigid muscles
  • Constricted pupils
  • Physical weakness
  • Itching
  • Depressed breathing, shallow breaths, or irregular breaths
  • Slowed heartbeat
  • Sweating
  • Flushing
  • Constipation
  • Dry mouth
  • Nausea

Taking this drug repeatedly, whether as prescribed or for nonmedical reasons, increases the risk of addiction, dependence, and tolerance. However, a person who takes this medicine as instructed by their doctor, and with that doctor’s supervision, is less likely to develop an addiction to this potent narcotic.

Fentanyl Patch Side Effects

Those who take fentanyl via transdermal patches as prescribed may develop redness, irritation, or a rash around the site where the patch attaches to the skin. This is moderately common, although it should be reported to a doctor. People who struggle with addiction to fentanyl are less likely to use transdermal patches as they should be used because this is a time-release method for taking the drug that does not result in euphoria. Instead, they may take the gel or liquid from inside the patch and tamper with it, so it can be injected all at once.

Fentanyl Tolerance and Dependence

Tolerance and dependence may still occur, even with a legitimate prescription. Tolerance means the body needs more of the drug to create the same effect – a common occurrence with opioid painkillers that fentanyl is designed to combat, so people with severe chronic pain can still get relief when other opioids stop working. Dependence means the brain needs a certain amount of the drug to reach chemical equilibrium. Even if the person is not addicted to fentanyl, a side effect of both tolerance and dependence is withdrawal. A doctor will likely taper the person off fentanyl or replace it with another drug. Fentanyl is not prescribed to people whose pain will go away, so it is rare for a patient to taper off the drug.
Side Effects of Fentanyl

Fentanyl Withdrawal

Withdrawal symptoms associated with opioids, including fentanyl, are:

  • Restlessness
  • Excessive yawning
  • Runny nose
  • Tearing or watery eyes
  • Trouble falling or staying asleep
  • Pain in the muscles, joints, or back
  • Enlarged pupils
  • Anxiety, irritability, or mood swings
  • Physical weakness
  • Loss of appetite and stomach cramps
  • Nausea, vomiting, or diarrhea
  • Rapid breathing and heart rate

There are other potential side effects, but these are less common. Rare side effects from fentanyl include:

  • Reduced urine output
  • Anxiety
  • Feeling cold
  • Headache or pain in the head
  • Abnormal heart rhythm
  • Low blood pressure
  • Chest pain
  • Coughing up blood
  • Dyskinesia, or trouble with voluntary movement
  • Nightmares
  • Feeling like the room is spinning
  • Stinging skin
  • Throat irritation
  • Kidney damage
  • Eczema or other skin disorder
  • Bloating or swelling of the face or extremities

Fentanyl Hallucinations

A very rare side effect from fentanyl is hallucinations. This is less likely to happen while a doctor supervises fentanyl use, but people who struggle with fentanyl abuse are at risk of experiencing auditory or visual hallucinations. The most common form of fentanyl hallucination is auditory, usually hearing voices that do not exist. However, other auditory hallucinations include music, clapping, or random sounds. Sometimes, a person may experience visual hallucinations, including seeing objects or people that are not actually present.

Last Updated on November 25, 2019
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