Fentanyl: What You Need to Know

Medically Reviewed by Carol DerSarkissian, MD on September 15, 2023
3 min read

Fentanyl is a human-made opioid used to treat severe pain. It's 50 to 100 times stronger than morphine. The drug interacts with receptors in your brain to create feelings of pain relief, relaxation, contentment, and pleasure.

While it’s safe for your doctor to give you fentanyl in a medical setting, some people abuse it, which can lead to an overdose.

A doctor might prescribe fentanyl if you have severe pain due to cancer, nerve damage, serious injury, or major surgery.

Medical fentanyl comes in many forms, including:

  • Lozenges, sometimes on a stick
  • Skin patches
  • As an injection or through an IV

Before giving you fentanyl, your doctor should ensure that you’re not allergic to it or to any other narcotic pain medications. Tell your doctor if you’ve ever had:

  • Sleep apnea
  • Breathing problems
  • A brain tumor
  • A head injury
  • A stroke
  • Seizures
  • Liver or kidney disease
  • Slow heartbeats or other heart problems
  • Low blood pressure
  • Mental illness, such as depression or schizophrenia
  • Hallucinations

Also, tell your doctor if:

  • You’ve used an antidepressant called a MAO inhibitor (isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine) in the last 14 days
  • You’re pregnant, plan to become pregnant, or are breastfeeding

This drug stays in your system for 24-72 hours.

After a fentanyl treatment, you may have side effects that hinder your thinking and reactions or cause dizziness or drowsiness. Because of this, don't drive or do activities that require you to be fully alert and awake after your treatment. Avoid drinking alcohol for several hours after you take fentanyl.

Fentanyl may cause other side effects. Let your doctor know if any of these symptoms don’t go away or become serious:

  • Drowsiness
  • Stomach pain or heartburn
  • Weight loss
  • Trouble peeing
  • Vision changes
  • Anxiety or depression
  • Unusual thinking or dreams
  • Trouble falling or staying asleep
  • Dry mouth
  • Sudden reddening of your face, neck, or upper chest
  • Shaking in any part of your body
  • Back or chest pain
  • Mouth pain, sores, or irritation in the location where you were given fentanyl
  • Swelling in your hands, feet, arms, ankles, or lower legs

Call your doctor right away if you notice:

  • Changes in your heartbeat
  • Hallucinations, agitation, fever, sweating, confusion, shivering, muscle stiffness or twitches, loss of coordination, nausea, vomiting, or diarrhea
  • Loss of appetite, weakness, or dizziness
  • Sexual or menstrual problems
  • Seizures
  • Hives or rashes
  • Itching

Seek emergency medical help and stop using fentanyl if you have:

  • Shallow, slow breathing
  • Trouble swallowing and breathing
  • Intense drowsiness
  • Dizziness or confusion
  • Fainting

Fentanyl is very addictive. It's one of the most common drugs involved in overdose deaths.

The drug can be manufactured illegally. Dealers may sell it as a standalone drug or as a counterfeit for another drug (like oxycodone). It's also used as a low-cost additive to other drugs like heroin, methamphetamine, molly, and ecstasy.

If you unknowingly take fentanyl in another drug, you may overdose, since fentanyl is so potent.

Fentanyl can also be “diverted.” That's when the drug is prescribed by a doctor but isn't used as directed or is sold or given to someone else.

Some people take fentanyl illegally by separating it from skin patches and injecting it. This can be dangerous since it’s hard to judge dose size. You could inject a lot more fentanyl than you thought.

Call an ambulance right away if you suspect you or someone you're with may have taken an overdose.

Signs of an overdose can show up within seconds of taking fentanyl, They include:

  • Blue lips and complexion
  • Gurgling or slow breathing
  • Chest pain
  • Seizure or stiffening of the body
  • Confusion or strange behavior
  • Passing out

First responders will likely administer naloxone (Narcan), a medication that reverses the effects of opiates.

You don't have to be a health care professional to give this medication. You can get it from a pharmacist without a prescription. It comes in a fast-acting nasal spray or a preloaded multiple-dose syringe. Some experts recommend having naloxone on hand whenever someone in the household is taking narcotics.

To prevent accidental fentanyl overdoses, you can use fentanyl test strips to ensure other drugs don’t contain the opioid. You can get them through some outreach programs, such as needle exchanges.