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Effects and Risks of Fentanyl

Effects and Risks of Fentanyl

Fentanyl is a potent opiate that is highly addictive.

Illicit fentanyl has tainted the drugs sold on the street. Anyone who uses street drugs, even once, is at risk of an accidental overdose. If your child is using street drugs, help them reduce the harm, and seek professional help.

Compared to other opioids, fentanyl is cheap for drug dealers to make into a street drug, but it is much more powerful. It is odourless and tasteless, and therefore hard for anyone using street drugs to detect. 2 milligrams of pure fentanyl (the size of about 4 grains of salt) is enough to kill the average adult. Because only a few grains is enough to kill, fentanyl is responsible for high rates of accidental overdose and overdose deaths.

Fentanyl affects the brain. Like heroin, morphine, and other opioid drugs, it works by binding to the body’s opioid receptors, which are found in areas of the brain that control pain and emotions.

Short-term effects of fentanyl use

Fentanyl can lead to short-term mental and physical effects.1

Mental effects

  • extreme happiness
  • dizziness
  • confusion
  • going “on the nod” (being in and out of consciousness)

Physical effects

Besides strong pain relief, fentanyl produces physical effects such as:

  • drowsiness
  • slow breathing
  • nausea and vomiting
  • smaller (constricted) pupils
  • itching or warm/hot sensation on the skin
  • constipation
  • sedation
  • problems breathing
  • unconsciousness
  • overdose

Life-threatening effects can occur within 2 minutes of use.

Long-term effects of fentanyl use

After taking opioids many times, the brain adapts to the drug, diminishing its sensitivity, making it hard to feel pleasure from anything besides the drug. When people become addicted, drug seeking and drug use take over their lives.

Real-world observations suggest that long-term use of fentanyl may have both mental and physical effects.

Mental effects

Repeated use of fentanyl can cause:

  • substance use disorder
  • depression and suicidal thoughts
  • difficulty in controlling impulsive behaviour

Physical effects

Long-term use of fentanyl can also lead to:

  • constipation
  • substance use disorder
  • sexual problems in men
  • poor nutrition, weight loss
  • irregular menstrual cycles in women

In some patients, particularly at high doses, chronic use of fentanyl can worsen pain.

If you think or know that your child is using fentanyl or street drugs, it is important to get help immediately.  It is also important to consider keeping an opiate antagonist like Naloxone on hand in case of an accidental drug overdose.

Signs of fentanyl overdose

Anyone can overdose on fentanyl. An overdose occurs when a drug produces serious adverse effects and life-threatening symptoms. When people overdose on fentanyl, their breathing can slow or stop. This can decrease the amount of oxygen that reaches the brain, a condition called hypoxia. Hypoxia can lead to a coma and permanent brain damage, and even death. 2

Physical signs of fentanyl overdose include:

  • Severe sleepiness/sedation
  • Slow, shallow breathing
  • Nausea
  • Respiratory arrest
  • Lips and nails turn blue
  • Confusion
  • Person is unresponsive or unconscious
  • Gurgling sounds or snoring
  • Cold and clammy skin
  • Tiny pupils
  • Drowsiness/respiratory depression
  • Coma

What to do if you suspect an overdose

If you think someone is overdosing on fentanyl or any other opioid: 3

  • Call 911 immediately for emergency medical assistance
  • Use naloxone, a drug that can temporarily reverse the effects of an opioid overdose
    • naloxone wears off in 20 to 90 minutes, so it is important to seek further medical attention
    • give the person another dose of naloxone if signs and symptoms do not disappear or if they reappear
  • Stay until emergency services arrive

Fentanyl Addiction and Withdrawal

Tolerance to fentanyl occurs when you need increased doses to produce the same effect. Physical dependence and substance use disorder can develop quickly, within weeks of regular use. Most long-term opioid users experience withdrawal. 4

Addiction is the most severe form of a substance use disorder (SUD). SUDs are characterized by compulsive drug seeking and drug use that can be difficult to control, despite harmful consequences. When someone is addicted to drugs, they continue to use them even though they cause health problems or issues at work, school, or home. An SUD can range from mild to severe.

People addicted to fentanyl who stop using it can have severe withdrawal symptoms that begin as early as a few hours after the drug was last taken. These symptoms include:

  • muscle and bone pain
  • sleep problems
  • diarrhea and vomiting
  • cold flashes with goose bumps
  • uncontrollable leg movements
  • severe cravings

These symptoms can be extremely uncomfortable and are the reason many people find it so difficult to stop taking fentanyl. Like other opioid addictions, medication with behavioural therapies has been shown to be effective in treating people with a fentanyl addiction. 5

  1. Health Canada –
  2. National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.
  3. Health Canada –
  4. Health Canada –
  5. .National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.

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