Can You Take Quetiapine with Lorazepam?

Severity assessment

Moderate. The concomitant use of lorazepam and quetiapine can lead to increased central nervous system (CNS) depression, resulting in excessive sedation, dizziness, confusion, and impaired coordination [1] [2] [3].

Mechanism (plain English)

Both lorazepam and quetiapine act on the central nervous system, but through different pathways. Lorazepam is a benzodiazepine that enhances the effect of gamma-aminobutyric acid (GABA), a neurotransmitter that calms brain activity, leading to sedative and anxiolytic effects. Quetiapine is an atypical antipsychotic that blocks several neurotransmitter receptors, including dopamine and serotonin, which contributes to its sedative and antipsychotic properties. When taken together, their combined CNS depressant effects are additive, meaning they amplify each other, leading to a greater degree of sedation and other CNS-related side effects. Additionally, some evidence suggests that quetiapine may enhance the CNS effects of lorazepam, and the mean oral clearance of lorazepam may be reduced by quetiapine, potentially increasing lorazepam levels in the body [3] [4] [5].

Evidence level

Regulator-flagged. Both the FDA labels for lorazepam and quetiapine, as well as the British National Formulary (BNF), highlight the risks associated with co-administration of CNS depressants [1] [2] [4].

Top regulator advisories (cite verbatim or close paraphrase)

• TGA (Australia): No specific public advisory for the lorazepam-quetiapine pair was found. However, the Australian Public Assessment Report for Quetiapine notes that "The mean oral clearance of lorazepam (2 mg, single dose) was reduced by 20 %" when co-administered with quetiapine [5].
• MHRA / NICE (UK): The British National Formulary (BNF) states that "Both Quetiapine and Lorazepam have effects on the CNS and can cause sedation, which might affect the ability to perform skilled tasks" [4].
• FDA / CDC (US): The FDA label for lorazepam warns about the concomitant use of benzodiazepines with other CNS depressants, stating it "may lead to potentially fatal respiratory depression" [2]. The FDA label for quetiapine indicates that quetiapine did not affect the single dose pharmacokinetics of lorazepam at 750 mg/day [1]. However, the general warning for CNS depressants from the lorazepam label is applicable.
• EMA (Europe): No specific EMA advisory for this exact pair was readily found within the scope of this research.

Clinical risk factors that elevate the danger

Patients at higher risk include the elderly, those with compromised respiratory function (e.g., COPD, sleep apnea), individuals with hepatic impairment, and those concurrently using other CNS depressants such as alcohol, opioids, or other sedatives. Rapid dose escalation of either medication can also increase the risk of adverse effects [2] [3] [6].

What a patient should be told

• Risk of severe drowsiness and breathing problems: Combining lorazepam and quetiapine can make you very sleepy, dizzy, confused, and can slow down your breathing to a dangerous level. Avoid driving or operating heavy machinery until you know how these medicines affect you.
• Do not stop suddenly: If you are taking these medications regularly, do not stop taking them abruptly without talking to your doctor or pharmacist. Suddenly stopping can lead to withdrawal symptoms, which can be serious.
• Watch for warning signs: Be aware of signs like extreme drowsiness, difficulty waking up, slow or shallow breathing, unusual dizziness, or confusion. If you experience these, seek medical attention immediately.
• Discuss alternatives: Talk to your doctor or pharmacist about all medications you are taking, including over-the-counter drugs, supplements, and herbal products. They can help assess your risk and discuss safer alternatives or dose adjustments.
• Urgent care triggers: If you or someone with you experiences severe difficulty breathing, unresponsiveness, or extreme confusion, seek urgent medical care or call emergency services immediately.

Top 3 sources (with full citation)

1. U.S. Food and Drug Administration. (2022). SEROQUEL (quetiapine) tablets, for oral use [Prescribing Information]. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/020639s072lbl.pdf
2. U.S. Food and Drug Administration. (2021). Ativan (lorazepam) Tablets [Prescribing Information]. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/017794s048lbl.pdf
3. Drugs.com. (n.d.). Lorazepam and Quetiapine Drug Interactions. Retrieved June 1, 2026, from https://www.drugs.com/drug-interactions/lorazepam-with-quetiapine-1488-0-1979-0.html

Notes for the reviewing pharmacist

While the quetiapine FDA label states no pharmacokinetic effect on lorazepam, the pharmacodynamic interaction leading to additive CNS depression is well-established and clinically significant. The TGA AUSPAR for quetiapine did note a 20% reduction in lorazepam clearance, which could contribute to increased lorazepam levels and enhanced CNS effects. This discrepancy highlights the importance of considering both pharmacokinetic and pharmacodynamic interactions. Clinicians should be particularly vigilant in elderly patients and those with respiratory or hepatic compromise. Patient education should emphasize the risks of profound sedation and respiratory depression, and the importance of not discontinuing medication abruptly. The potential for misuse and abuse of lorazepam, a benzodiazepine, should also be considered in the overall risk assessment.

Source metadata JSON

{
  "pair": "lorazepam + quetiapine",
  "severity": "Moderate",
  "evidence_level": "Regulator-flagged",
  "source_urls": "https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/020639s072lbl.pdf;https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/017794s048lbl.pdf;https://www.drugs.com/drug-interactions/lorazepam-with-quetiapine-1488-0-1979-0.html;https://bnf.nice.org.uk/interactions/quetiapine/;https://www.tga.gov.au/sites/default/files/auspar-seroquel.pdf;https://www.goodrx.com/lorazepam/lorazepam-interactions?srsltid=AfmBOoqtF4Fib5082qv8FevkFGKyn84XSe1Ota9GKzPNZfjFpJAqeSrK;https://mountainvalleyrecovery.com/what-drugs-should-you-not-take-with-lorazepam/;https://www.droracle.ai/articles/716153/how-to-manage-an-elderly-male-patient-with-a;https://www.droracle.ai/articles/712393/what-are-the-potential-interactions-between-buspar-buspirone-lorazepam;https://link.springer.com/article/10.2165/00128415-200812040-00070"
}