
Fentanyl is a dangerous and deadly opioid drug. Once a substance only used in hospitals and hospices, it has made its way out onto the street, becoming an increasing problem for people with opioid use disorder (OUD).
Knowing what fentanyl use looks like is critical, as the drug can be deadly. Fentanyl is so incredibly potent — up to 50 times more powerful than heroin and 100 times stronger than morphine — that even very small amounts can result in an overdose.[1]
The sooner a person recognizes that treatment is needed and connects with treatment, the sooner they are free of potential overdose, accidents while under the influence, and acute and chronic health conditions that can result from fentanyl use.
Fentanyl, a synthetic opioid, was first synthesized in 1959 and used primarily as an anesthetic and pain reliever during surgical procedures in a hospital setting.[2]
However, in recent years, fentanyl has made its way out of hospitals and hospices and onto the black market, becoming a significant public health concern in the United States.
Because fentanyl is cheap to create and highly addictive, it creates a greater profit margin for dealers.[3] They add the drug to other opioids (like heroin) and completely different substances (like marijuana, cocaine and ecstasy).
Researchers say that 6 in 10 prescription pills sold by dealers now contain a potentially lethal dose of fentanyl.[4] Death rates are rising accordingly.
According to the Centers for Disease Control and Prevention (CDC), there were more than 80,000 overdose deaths due to opioids in 2021 and nearly 88% of these deaths involved synthetic opioids like fentanyl.[5]
Like all opioids, fentanyl attaches to receptors within the brain, triggering the release of chemicals like dopamine, which can cause feelings of euphoria and relaxation. Almost all of the symptoms people experience are caused by this chemical release.
Experts say fentanyl’s effects include extreme happiness.[6] The brain is flooded with chemicals that make the person feel an extreme ‘high’. The effect is short-lived and followed by sedation.
After using fentanyl multiple times, brain cells adapt by producing less dopamine without drugs. People who regularly use end up struggling to experience pleasure from anything that isn’t fentanyl. An opioid use disorder (OUD) related to fentanyl use develops quickly.[6]
Several behavioral and physical changes occur when someone is under the influence of fentanyl. These changes, or signs, can indicate a fentanyl use disorder if the person does not have a prescription.
Some of these symptoms are serious. Understanding what they look like is critical, as an overdose can be fatal. Spotting them could mean the difference between life and death.
Symptom severity is based on how much fentanyl people take. The more you use, the more significant the difficulties.
Common physical symptoms associated with opioid intoxication include the following:[7]
Behavioral and mental changes can be as much of an indicator of fentanyl use as physiological changes.
Mental health symptoms of fentanyl use can include the following:[7]
Researchers know how drug use changes adolescent behaviors. Many of these adjustments are seen in adults too. The following problems are common in those who regularly use fentanyl:[8]
Fentanyl withdrawal can be challenging and uncomfortable, both physically and mentally.
Here are some signs and symptoms that may indicate that your friend or family member may be going through fentanyl withdrawal:[9]
Symptoms typically begin about 12 hours after the last dose, and they can last for about a week.[9] Moving through this process alone is very difficult, and it can be dangerous. Treatment is important, particularly use of Medication for Addiction Treatment (MAT).
Fentanyl overdose can be deadly, so early identification is key. The sooner someone gets medical treatment, the more likely it is that they will survive without long-term consequences.
Experts say an opioid overdose is identified by the following three signs and symptoms:[10]
A fentanyl overdose can be fatal if it’s not handled quickly and properly. Fentanyl overdose can be stopped with medical treatment and the administration of naloxone.
Naloxone binds to opioid receptors, kicking off fentanyl and immediately blocking its effects. If someone you love uses opioids, keep this medication with you at all times.
If you think someone is overdosing, take the following steps:[11-13]
MAT can help people who are addicted to fentanyl stop using, avoid overdose risks and develop a healthier life. In the past, enrolling in MAT meant visiting a clinic every day. Bicycle Health is different.
Bicycle Health offers MAT via telehealth appointments. Meet with a professional online and pick up a prescription at a pharmacy near you. Contact us to see if this model is right for you.

Peter Manza, PhD received his BA in Psychology and Biology from the University of Rochester and his PhD in Integrative Neuroscience at Stony Brook University. He is currently working as a research scientist in Washington, DC. His research focuses on the role of the brain dopamine system in substance use disorders and in aging. He also studies brain function in obesity and eating disorders.
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