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What are the Different Fentanyl Side Effects?

M.C. Huguelet
M.C. Huguelet

Fentanyl is an extremely strong painkiller, or analgesic, which is normally used in patients for whom weaker painkillers have become ineffective. There are a number of potential fentanyl side effects. Some of these side effects, such as digestive system upset and reduced alertness, are mild to moderate in severity. Others, such as slowed breathing, can be life threatening if left unattended. Understanding the possible fentanyl side effects is key to using this drug safely.

A number of common fentanyl side effects involve interruption to normal digestive system function. For instance, some fentanyl users experience nausea and vomiting, while others report constipation. Such side effects can be unpleasant, but they are usually not serious. Drinking plenty of fluids can help ease constipation as well as prevent dehydration in those experiencing vomiting.

Hives may indicate a medication allergy.
Hives may indicate a medication allergy.

Some fentanyl side effects disrupt one’s sense of awareness. Certain users may experience dizziness, blurred vision, confusion, or drowsiness. While these side effects themselves generally pose no significant risk to one’s health, they can make many normal daily activities, such as driving a car or walking up stairs, dangerous. Fentanyl users should be on guard for feelings of reduced awareness. Should such feelings occur, users should avoid performing activities which require full coordination and concentration.

Some Fentanyl users experience nausea and vomiting.
Some Fentanyl users experience nausea and vomiting.

Certain fentanyl side effects can be life threatening if left unattended. Some individuals, for instance, experience slowed breathing while taking fentanyl. Users experiencing respiratory difficulties should immediately seek medical attention if their breathing slows to uncomfortable levels. Further, individuals with pre-existing respiratory conditions will need to consult their physicians to discuss their suitability for treatment with fentanyl.

Some fentanyl side effects may signal a serious allergic reaction to the medication. These side effects may include skin rash or hives, itching, swelling of the face or mouth, fever, or extreme disorientation. Those who observe one or more of these side effects in themselves or a loved one who is taking fentanyl should immediately seek emergency medical care. If left untreated, an allergic reaction to fentanyl can lead to death.

It should be noted that fentanyl can cause a range of additional side effects when taken in combination with certain other medications. To learn what these side effects may be and how to respond to them, users should inform their physicians of all other prescription, non-prescription, and herbal drugs they are taking at the time that fentanyl is prescribed. Being aware of the possible fentanyl side effects is critical to safe use of the drug.

Discussion Comments

googie98

I wanted to add to the article that you should not drink grapefruit juice while on the Fentanyl patch. It can cause the medication to be delivered at a higher dose and can lead to serious problems, including death.

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    • Hives may indicate a medication allergy.
      By: Jürgen Fälchle
      Hives may indicate a medication allergy.
    • Some Fentanyl users experience nausea and vomiting.
      By: Johan Lenell
      Some Fentanyl users experience nausea and vomiting.