Can Fentanyl Cause Seizures? Drug Abuse as a Seizure Trigger

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Table of Contents

Can Fentanyl Cause Seizures?
Can Fentanyl Withdrawal Cause Seizures?
Why Drug Abuse Can Trigger Seizures
Signs of a Fentanyl-Related Seizure
Fentanyl Overdose vs. Seizure: How to Tell the Difference
What to do if someone has a seizure due to fentanyl use
Can Seizures Cause Permanent Brain Damage?
Fentanyl Addiction Treatment in Los Angeles

Medically Reviewed

Written by: Jessica Downs

Reviewed by: Sareen Khodabakhsh, LMFT

September 09, 2026

Fentanyl is a synthetic opioid 80–100 times more potent than morphine, with a high risk for respiratory depression, overdose, and death. But can fentanyl induce seizures? Seizures are not a common complication of fentanyl use, but they can occur under certain circumstances, including severe intoxication, oxygen deprivation during an overdose, drug interactions, and in individuals who are already prone to seizures.

Drugs may directly alter the electrical activity of the brain or create conditions that make seizures more likely to occur. This is especially true with illicit fentanyl, as the substance may be mixed with stimulants, sedatives, or other compounds without the person’s knowledge. Illegally made fentanyl is often combined with heroin, cocaine, or methamphetamine or found in powders and counterfeit pills, the CDC says.

Understanding the link between fentanyl, withdrawal, overdose, and seizures can help people identify a medical emergency and understand the importance of professional treatment.

Can Fentanyl Cause Seizures?

So, can fentanyl cause seizures directly? The answer is yes, although seizures are considered an uncommon complication compared with respiratory depression and overdose.

The FDA prescribing information for fentanyl citrate injection includes seizures among its warnings and precautions and notes that fentanyl may increase the frequency of seizures in patients with seizure disorders and may increase the risk of seizures in other clinical settings.

Research also provides evidence that fentanyl can produce seizure activity under certain conditions. A study published in the Journal of Neurosurgery examined nine patients with complex partial epilepsy. Eight showed electrical seizure activity after administration of fentanyl during anesthesia. “The circumstances and fentanyl doses used in this study are very different from typical illicit fentanyl exposure, so these findings should not be taken as evidence that every person who uses fentanyl will have a seizure.” However, the study indicates the possibility that fentanyl may influence seizure activity in susceptible patients.

Another big concern is indirect seizure activity from an overdose. Fentanyl can severely depress breathing. When the brain does not get enough oxygen (hypoxia), neurological injury and seizures can occur. The Epilepsy Foundation says if you take a lot of opioids, your brain may not get enough oxygen and you could have a seizure.

This risk is one reason understanding why fentanyl is so dangerous is important for anyone using fentanyl or other illicit opioids.

Can Fentanyl Withdrawal Cause Seizures?

Another common question is, “Can fentanyl cause seizures when someone suddenly stops using it?”

An opioid withdrawal seizure is possible, but seizures are not considered a typical feature of uncomplicated opioid withdrawal. Classic opioid withdrawal symptoms more commonly include anxiety, restlessness, sweating, muscle aches, abdominal cramping, nausea, vomiting, diarrhea, insomnia, and increased heart rate.

When a seizure occurs during suspected fentanyl withdrawal, healthcare professionals should consider additional explanations rather than automatically assuming opioid withdrawal caused it.

These may include withdrawal from alcohol or benzodiazepines, stimulant exposure, metabolic abnormalities, dehydration, head injury, epilepsy, medication interactions, contamination of the illicit drug supply, or complications of a recent overdose.

Because illicit fentanyl exposure can be unpredictable, medically supervised fentanyl detox provides an opportunity for withdrawal symptoms and potential complications to be evaluated by trained professionals.

Why Seizures May Occur During Opioid Withdrawal?

The possibility of a drug-induced seizure may be greater when multiple risk factors are present. These can include a previous seizure disorder or epilepsy, history of traumatic brain injury, polysubstance use, abrupt alcohol or benzodiazepine discontinuation, stimulant use, severe dehydration, electrolyte abnormalities, prolonged sleep deprivation, and a recent opioid overdose involving oxygen deprivation.

People who regularly use multiple substances should provide healthcare professionals with as much information as possible about what they have taken and when. Knowing approximately how long does fentanyl stay in your system can also help patients better understand detection windows and why withdrawal and toxicology findings do not always follow identical timelines.

Risk Factors That Increase Seizure Risk During Withdrawal

Although an opioid withdrawal seizure is uncommon, withdrawal places considerable stress on the nervous system. Long-term opioid exposure produces neuroadaptations as the brain attempts to maintain normal function in the presence of the drug. Abrupt discontinuation can produce autonomic and neurological hyperactivity.

Seizures occurring during this period may also result from a combination of factors rather than withdrawal alone. Factors that may lower the seizure threshold include sleep deprivation, dehydration, electrolyte disturbances secondary to severe vomiting or diarrhea, co-existent withdrawal from substances, and underlying neurological conditions.

Therefore, anyone asking if opioids can cause seizures during withdrawal should understand that a seizure warrants medical evaluation to determine its actual cause.

Why Drug Abuse Can Trigger Seizures

If you’re wondering whether drugs can cause seizures, it’s important to understand that different substances influence seizure risk in different ways. Certain drugs directly increase neuronal excitability, whereas other drugs mainly produce a risk of seizures via overdose, withdrawal, or secondary complications.

Opioids

Can opioids cause seizures? They can under certain circumstances, although seizures are less characteristic of opioid use than respiratory depression.

Seizures are a direct neurologic effect of fentanyl and other opioids in susceptible individuals or, indirectly, from severe respiratory depression and hypoxia. Opioid use may also complicate seizure management when a person misses prescribed anticonvulsant medication.

For people who have developed opioid dependence, medically supported opioid detox in Los Angeles can help clinicians monitor withdrawal and identify complications that require additional medical attention.

Alcohol

Alcohol is particularly important when discussing what drugs cause seizures because abrupt alcohol withdrawal is a well-established seizure trigger.

The Epilepsy Foundation reports that alcohol-related seizures frequently occur during withdrawal rather than intoxication itself. Withdrawal seizures can occur approximately 6 to 72 hours after alcohol consumption stops, and severe withdrawal can progress to status epilepticus, a potentially fatal emergency.

Benzodiazepines

Benzodiazepines suppress central nervous system activity. With prolonged or heavy use, the nervous system adapts to their presence.

Suddenly discontinuing benzodiazepines can produce severe neurological hyperexcitability, including seizures. This is why people who are physically dependent on benzodiazepines should not abruptly stop taking them without appropriate medical guidance.

The risk becomes especially important when fentanyl and benzodiazepines are used together, because both can suppress breathing while benzodiazepine withdrawal itself may create seizure risk.

Cocaine and methamphetamine

Stimulants are another important answer to the question “What drugs cause seizures?”

Cocaine can cause seizures even in individuals without a previous seizure disorder. According to the Epilepsy Foundation, seizures associated with cocaine can develop seconds, minutes, or hours after use and may occur alongside cardiac arrhythmias, heart attacks, and death. High doses of amphetamines can also cause severe tonic-clonic seizures and cardiovascular complications.

Methamphetamine intoxication can similarly produce extreme sympathetic stimulation, hyperthermia, agitation, cardiovascular complications, and seizures.

Synthetic drugs

Synthetic and illicitly manufactured substances create additional risks because consumers may not know exactly what they are taking.

Counterfeit pills can look like legitimate prescription drugs, but they may contain illegally made fentanyl. Fentanyl can also appear in substances sold as cocaine, methamphetamine, or other drugs.

This unpredictability means a drug-induced seizure may involve fentanyl, another substance, an adulterant, or several drugs acting together.

A seizure does not always involve dramatic full-body convulsions. Generalized tonic-clonic seizures may include loss of consciousness, body stiffening, rhythmic jerking of the arms and legs, abnormal breathing, drooling, jaw clenching, loss of bladder control, and confusion or extreme fatigue afterward.

Other seizures may result in staring, brief periods when you cannot respond, odd repetitive motions, or changes in awareness.

If a person experiences a first-time seizure after fentanyl or other drug use, emergency medical evaluation is appropriate. The question is not simply whether fentanyl causes seizures but whether overdose, hypoxia, polysubstance exposure, withdrawal, trauma, or another medical condition is responsible.

Fentanyl Overdose vs. Seizure: How to Tell the Difference

A fentanyl overdose and seizure can sometimes look similar, particularly when a person suddenly becomes unconscious.

Classic opioid overdose warning signs include severe unresponsiveness, very slow or absent breathing, pinpoint pupils, limpness, choking or gurgling sounds, and blue, gray, or pale lips or skin.

A generalized seizure more commonly involves stiffening followed by repetitive jerking movements. Afterward, the person may gradually begin breathing more normally but remain confused or exhausted.

The distinction is not always obvious, and both conditions can occur together. Severe opioid-induced respiratory depression may cause oxygen deprivation that contributes to seizure activity.

When fentanyl exposure is suspected, treat the situation as a potential overdose and medical emergency rather than attempting to determine the exact diagnosis yourself.

What to Do if Someone Has a Seizure After Using Fentanyl

What to do if someone has a seizure due to fentanyl use

Call 911 immediately if someone has a seizure after known or suspected use of fentanyl, especially if this is the first seizure, a seizure lasts five minutes or longer, another seizure occurs, they are injured, or they have trouble breathing or regaining consciousness.

Get the person away from any nearby hazards. If possible, cushion the head. Do not restrain the person’s movements. Never put an object, food, medication, or your fingers into the person’s mouth.

Once convulsive movements stop, place the person on their side if this can be done safely and monitor breathing.

If opioid overdose is suspected, administer naloxone if it is available and follow emergency-dispatch instructions. Naloxone can temporarily reverse opioid-induced respiratory depression and will not harm someone simply because opioids turn out not to be the cause of their condition.

Can Seizures Cause Permanent Brain Damage?

Most brief seizures do not automatically result in permanent brain damage. The risk depends on the type and length of the seizure and what caused it.

If the seizure lasts a long time, or if several seizures happen without the person returning to normal in between, then it can become status epilepticus. This is a medical emergency. Brain injury can also occur due to prolonged lack of oxygen from a fentanyl overdose.

This distinction is important. In some fentanyl-related emergencies, neurological injury may result primarily from hypoxia rather than the seizure itself.

Even if a person seems to have fully recovered from a drug-induced seizure, a doctor should examine him or her. Clinicians may need to consider oxygenation, blood glucose, electrolytes, toxicology results, neurological status, head injury, medication history, and other possible causes.

Fentanyl Addiction Treatment in Los Angeles

Despite a recent drop in overdose deaths, fentanyl remains a significant public health threat in Los Angeles.

Drug-related overdose and poisoning deaths decreased for the third consecutive year in 2025, the Los Angeles County Department of Public Health said. Total deaths declined another 6% from 2024, with fentanyl deaths down 10%. That follows a record drop in 2024 when fentanyl-related deaths fell 37 percent.

Fentanyl remains dangerous, but there is a lot of progress. The CDC reported that 47,735 people died from overdoses involving synthetic opioids other than methadone (such as fentanyl and fentanyl analogs) in the country in 2024.

If you are someone who takes fentanyl repeatedly, the question “Can fentanyl cause seizures?” is only one part of a much larger risk profile. High rates of physical dependence, respiratory depression, accidental overdose, polydrug exposure, and potentially life-threatening complications may be associated with fentanyl use.

Fentanyl addiction treatment in Los Angeles addresses the physical dependence to fentanyl along with the behavioral and psychological components that drive fentanyl use.

Treatment may include medically supervised withdrawal management, medications for opioid use disorder, individual and group therapy, relapse prevention planning, behavioral interventions, mental health services, and ongoing recovery support as appropriate.

So, does fentanyl cause seizures? It can, but seizures associated with fentanyl use require careful medical assessment because several mechanisms may be involved. And while an opioid withdrawal seizure is possible, seizures are not a typical feature of uncomplicated opioid withdrawal. Consider coexisting alcohol or benzodiazepine withdrawal, stimulant exposure, underlying neurologic disorders, metabolic abnormalities, or complications of overdose.

Anyone who has a seizure after using fentanyl or stopping fentanyl use should get prompt medical evaluation. For people struggling with ongoing fentanyl use, professional treatment can address the underlying addiction before another overdose or serious medical complication occurs.