In a recent and troubling development, Quetiapine, usually prescribed for mental health patients as an atypical antipsychotic better known by its brand name Seroquel, is now also being seen in street drug testing labs in a handful of states including Wisconsin. Now turning up as an undisclosed adulterant in illicit heroin, it is usually unknown to heroin users.
For those working in addiction treatment, rehabilitation, emergency services and public health, this trend signals a deeply concerning shift in the illicit substance market — one that could complicate treatment, increase overdose risk, and hinder recovery.
Table of Contents
- What Is Quetiapine and Why Is It Prescribed?
- Quetiapine: A Hidden Guest in Heroin
- Why Is Quetiapine Showing Up in Heroin?
- Why is Quetiapine in illicit drugs a cause for concern?
- How Quetiapine complicates opioid overdoses and the best way to treat it
- Quetiapine’s Adverse Effects in Illicit Use and Notes for First Responders
- Understanding Quetiapine Withdrawal Symptoms
- Quetiapine’s street allure and nicknames
- Combating Quetiapine in Illicit Drugs
- Why Wisconsin Is at Risk
- Getting help with opioid addiction
What Is Quetiapine and Why Is It Prescribed?
Quetiapine (Seroquel) is a prescription-only FDA-approved atypical antipsychotic medication for:
- Treatment of schizophrenia (in adults and adolescents)
- Bipolar disorder, be it a depressive or a manic episode
- Adjunctive treatment of major depressive disorder
Off-label uses:
While not officially approved for these conditions, doctors sometimes prescribe Quetiapine for:
- Generalized anxiety disorder (GAD)
- Insomnia (at low doses)
- Post-traumatic stress disorder (PTSD)
Quetiapine works by balancing certain brain chemicals—mainly dopamine and serotonin—to help regulate mood, thought patterns, and perception.
When used properly under medical supervision, Quetiapine can be life-changing for individuals struggling with severe mental health conditions. The danger arises when it is misused or introduced into the illicit drug supply—without user knowledge, dosage control, or medical oversight.
Quetiapine (Seroquel) in its medication form is prepared and dispensed into immediate-release and extended-release categories; low-dose tablets (like quetiapine fumarate 25 mg) may also be prepared and dispensed, based on the clinical diagnosis and response in the patient.
Quetiapine can be sedative, relaxing, and sometimes even euphoric. Such effects at higher doses, or when taken without medical supervision, have seen the drug’s use being abused, sometimes by itself and sometimes mixed with other substances.
Quetiapine: A Hidden Guest in Heroin
A recent community-based drug checking study in Los Angeles (Published in- Journal of Addiction Medicine), found that 25% of heroin samples analyzed contained quetiapine. The users, who believed they were buying black tar heroin, were unaware of the presence of this substance.
Some reported experiencing unusual effects — increased euphoria and a “pins and needles” sensation — which they attributed to the seemingly adulterated product.
Why Is Quetiapine Showing Up in Heroin?
On a most basic level, the reason dealers add adulterants to the mix of drugs is usually for reasons which may easily apply to Quetiapine. To increase profit, modify or enhance effects, or adjust potency. In essence, dealers may add in Quetiapine to:
- Alter the “feel” of the high and differentiate their product
- Offset stimulant effects in “speedball” combinations
- Stretch heroin supply with a non-opioid filler
- Exploit users’ desire for stronger sedation
Furthermore, the study’s analysis showed: Among heroin samples testing positive for quetiapine, only 31% also contained fentanyl, whereas 69% of quetiapine-negative samples had fentanyl. In other words, heroin samples containing Quetiapine had less fentanyl contamination than those without. Although in early 2023 a study by CFSRE showed Fentanyl and quetiapine co-positivity in toxicology samples collected in the United States has increased from 2018 to Q1 2023, still, while co-positivity possibly increased compared to pre-2018 levels, quetiapine seems to be viewed more recently by dealers mostly as a replacement for fentanyl.
This suggests quetiapine might be used recently as a more available, less risky—but still dangerous—adulterant instead of more typical additions like fentanyl or methamphetamine. Dealers seem to be experimenting with alternative cutting agents to alter the “feel” of the heroin high. This may be due to a limitation in the widespread availability of Fentanyl or the fear of that occurring in the near future, or due to other financial or liability considerations.
Why is Quetiapine in illicit drugs a cause for concern?
Quetiapine can cause sedation, dizziness, weight gain, akathisia, and complex withdrawal symptoms. And though this exploratory study didn’t find an elevated risk of overdose, the unknown presence of quetiapine adds serious uncertainty to illicit drug use.
This mix of potent opioids with an unexpected sedative can increase overdose complexity. For example, a person showing extreme drowsiness, confusion, and low blood pressure after suspected heroin use may not respond as expected to treatment. The combination of Quetiapine and heroin or other drugs complicates the risks of overdose. There is no overdose reversal drug for Quetiapine, unlike for opiates. That means if a patient overdoses on heroin-quetiapine, naloxone (Narcan) could reverse opioid effects and thus help for the heroin, but would not counter the sedation effect and respiratory depression caused by the Quetiapine.
Fentanyl strips, an increasingly common tool in the fight against opioid deaths, which helps detect Fentanyl being surreptitiously mixed in or used to “cut” other drugs and make them exponentially more fatal, are also not able to detect Quetiapine.
Additionally, due to the common legal use of Quetiapine, toxicology testing of drug users or overdose deaths, by itself, will not determine if the quetiapine detected was legitimately prescribed for therapeutic use or if its presence is due to illicit drug adulteration, and as such poses a difficulty in being able to properly assess the prevalence of the illicit drug in cities without the -less available- use of sophisticated sample testing.
As Meir Kasnett, CEO of Wellbrook Recovery, expressed when discussing this matter, “Getting accurate information on which substances are in a prospective patients body at the time of admission is difficult enough as it is. Whether it be due to shame and concealing the true extent of the toxins in their body, or a simple mistake in their recollection, or the unfortunate surreptitious lacing of other drugs with “cutters” and “fillers” that the user is not fully aware of.
Regardless, when trying to detox and treat, we need to know the most we can about what exactly has been used -and we often can’t know 100%. This emerging challenge with quetiapine lacing, I think, is going to complicate this process even more. People need to be made aware of this, and professionals need to begin taking this into account.”
How Quetiapine complicates opioid overdoses and the best way to treat it
In cases where a heroin overdose is complicated by quetiapine (Seroquel) use, emergency care focuses on addressing both the opioid and non-opioid effects. The immediate priority is securing the airway and ensuring adequate breathing, often with supplemental oxygen or assisted ventilation if necessary. Naloxone (Narcan) is still administered promptly to reverse the heroin’s effects on the brain’s opioid receptors, and breathing may improve if opioids are the primary cause of respiratory depression.
However, if the patient remains significantly sedated after Narcan, this suggests quetiapine’s sedative and depressant effects are still in play. Unlike opioids, there is no specific antidote for quetiapine, so treatment relies on supportive measures such as oxygen therapy, IV fluids for low blood pressure, and heart monitoring to detect potential rhythm disturbances.
Because Narcan’s effects last only 30–90 minutes and heroin’s effects can re-emerge once it wears off, patients require extended observation. Quetiapine’s half-life (6–12 hours or longer) means sedation and respiratory risks can persist well beyond the opioid reversal window.
This combination of drugs often necessitates prolonged monitoring in the ER or ICU, with the potential for mechanical ventilation until the sedative effects resolve. Ultimately, while Narcan remains effective against heroin, the presence of quetiapine can mask the improvement or maintain dangerous levels of sedation, making continuous medical supervision essential even after apparent reversal of the opioid overdose.
Quetiapine’s Adverse Effects in Illicit Use and Notes for First Responders
Under medical care, side effects of Quetiapine are monitored and managed. But in the context of illicit use — especially when mixed unknowingly with heroin or other drugs— the dangers can be severe and even fatal.
Short-term adverse effects may include:
- Excessive sedation or drowsiness
- Low blood pressure and fainting
- Blurred vision and dizziness
- Irregular heart rhythms
- Slowed breathing (when combined with opioids)
Long-term side effects can include:
- Weight gain and metabolic changes
- Increased risk of diabetes
- Hormonal imbalances
- Persistent cognitive dulling
- Quetiapine hallucinations or worsening mental health symptoms in some cases
Respiratory depression is the greatest danger to be aware of. Sedating effects of Quetiapine, combined with the effects of opioids, can cause significant slowing of breathing to critical levels.
The Center for Forensic Science Research & Education offers the following recommendations for Clinicians:
- Be aware that illicit drugs such as fentanyl, cocaine, and heroin may contain quetiapine, which can complicate the clinical presentation.
- Be familiar with the signs and symptoms associated with quetiapine toxicity. Including:
-Sedation particularly when combined with alcohol, benzodiazepines, and opioids.
-Dizziness
-Delirium/confusion
-Orthostatic hypotension
-Cardiac dysrhythmia
-QTc prolongation
-Hyperglycemia
-Respiratory depression
-Rare effects: seizures including late onset and neuroleptic malignant syndrome
- The range of toxicity of quetiapine overdose is highly variable and influenced by drug co-ingestions and underlying medical illnesses such as long QTc.
Understanding Quetiapine Withdrawal Symptoms
Quetiapine users usually are those who have gotten it prescribed by their medical practitioners, and there may even be those who would obtain it somehow out of their will to self-medicate. However, even with original proper intentions, overuse and prolonged usage may cause physical dependence to set in. As an unknown “cutting” agent or adulterant in illicit drugs, the dosage and intake remain unmonitored, and once the intake has stopped withdrawal symptoms might suddenly start without understanding why and what is being experienced resulting in a very confusing and sometimes dangerous situation.
Typical Quetiapine withdrawal symptoms include:
- Nausea, vomiting, and stomach discomfort
- Insomnia or vivid, distressing dreams
- Heightened anxiety or agitation
- Headaches and body aches
- Return or worsening of psychiatric symptoms
Quetiapine withdrawal timeline:
- First 24–48 hours: Initial rebound symptoms such as insomnia and irritability.
- Days 3–7: Nausea, anxiety, and mood swings peak.
- Week 2 and beyond: Gradual improvement, though psychiatric symptoms may persist in those with underlying conditions.
Quetiapine detoxification, especially when used in conjunction with an opioid, should always be carried out under professional supervision to monitor the patient for withdrawal manifestations and drug interactions.
Quetiapine’s street allure and nicknames
In drug misuse cultures, recreational users sometimes refer to chasing a “Quetiapine high” because the drug is marketed for sedation and calming effects.
Nicknames given to the drug on the street include “Susie-Q”. “Baby Heroin” or “Q-ball”, are names often used when referring to cocaine or heroin combined with Quetiapine.
Combating Quetiapine in Illicit Drugs
This being an increasing threat, experts emphasize harm reduction approaches that work at multiple layers.
Key strategies include:
- Drug Checking Programs: Drug testing facilities can check for Quetiapine and other adulterants in the illicit drug supply to identify the location and extent of the problem.
- Treatment: Training and providing tools to first responders, and timely, appropriate treatment at detox and rehab centers for the affected.
- Community Education: Informing the general public about the adverse effects of emerging fake drugs and adulterants.
- Safe Drug-Use Messaging: Promoting informed choices and referring to harm reduction resources.
Why Wisconsin Is at Risk
In the last couple of years, the state of Wisconsin has experienced highs and lows in opioid-related fatalities. While real progress has been made recently through educational and awareness programs and Narcan availability, opioid overdoses still remain terribly high and are well above the national average in the state’s main cities. Considering the fact that Quetiapine adulteration is a new and emerging threat identified in Wisconsin with almost no attention and education, and the inability for Narcan to help with an overdose complicated by the presence of Quetiapine, this should be an issue of concern.
Overdoses and deaths related to opioids occur in both cities and the rural areas. A DEA intelligence report from March 2025 focused on Wisconsin highlights that Mexican drug trafficking organizations (like the Sinaloa and Jalisco Nueva Generación cartels) remain dominant in supplying fentanyl, heroin, methamphetamine, and cocaine. “The current threat across the state is the availability, distribution, and abuse of fentanyl, followed by methamphetamine. Heroin and marijuana availability remain high.” The report noted.
Quetiapine sprinkled into this toxic brew leads to a whole different set of challenges for emergency responders, hospitals, and rehab facilities. And the lack of or limited availability of harm reduction infrastructure in places simply adds to these dangers, which calls for even more needful education, testing, and access to treatment.
In summary, the emergence of Quetiapine as an adulterant in Wisconsin’s heroin supply highlights the growing unpredictability and danger of today’s illicit drug market. While Quetiapine is a legitimate medication that can be life-changing when prescribed appropriately, its hidden presence in street drugs creates serious risks, from complicating overdoses to undermining the effectiveness of lifesaving treatments like Narcan. With overdose rates in Wisconsin already at problematic levels, this development underscores the urgent need for expanded drug checking programs, first responder training, community education, and access to treatment. Protecting vulnerable individuals will require vigilance, awareness, and proactive harm reduction measures before this trend worsens.
Getting help with opioid addiction
The detection of Quetiapine in Wisconsin’s drug market underscores the unpredictable and dangerous nature of present-day street drugs. Every dose is a gamble, and new adulterants are being constantly introduced.
It is time to act now if you or anyone you know are struggling with heroin, fentanyl, quetiapine or any polysubstance use. Our Wisconsin rehab center provides:
- 24/7 medically supervised detox
- Residential longer-term inpatient care
- Individualized treatment programs
- Therapy for co-occurring mental health conditions
- Long-term recovery support
Recovery is possible. Call us today for compassionate, confidential help.
