General, opioid-like side effects from fentanyl use – which may include those that occur due to prescription use – are:
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.
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.
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.
Withdrawal symptoms associated with opioids, including fentanyl, are:
There are other potential side effects, but these are less common. Rare side effects from fentanyl include:
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.