#299 Cannabis And Anesthesia

Cannabis has gone mainstream, but perioperative risk has not improved. THC products are far more potent than they were decades ago, emergency room visits are climbing, and many patients still walk into surgery thinking that it’s safe. We want anesthesia professionals to have a clearer, evidence-informed way to think about cannabis and anesthesia before the next case. 

We open the latest APSF newsletter feature article, “Cannabis and Anesthesia,” and bring in author Trisha Meyer to frame why this topic matters now. Together, we walk through the pharmacology that shows up at the bedside: THC vs CBD, CB1 and CB2 receptors, the endocannabinoid system, and how route of use changes onset and duration. Then we get practical about drug-drug interactions and highlight a free interaction-checking resource you can use in real time.

From there, we map cannabis use across the perioperative timeline. Preop means asking better questions and documenting details like product type, dose, frequency, last use, and withdrawal symptoms, plus knowing when intoxication should delay elective surgery and when cardiac risk may need more workup. Intraop means expecting possible higher propofol and sedative requirements, watching for cardiovascular instability, and preparing for airway hyperreactivity and bronchospasm in inhaled users. Postop means planning for higher pain needs, using multimodal analgesia, and recognizing withdrawal, hypothermia, and shivering patterns that can surprise teams.

If you care about perioperative patient safety, listen, share this with a colleague, and subscribe so you don’t miss what’s next.

For show notes & transcript, visit our episode page at apsf.org: https://www.apsf.org/podcast/299-cannabis-and-anesthesia/

© 2026, The Anesthesia Patient Safety Foundation

Transcript

Why High Potency Raises Risk

SPEAKER_00 0:00

What I hope to see is more research and studies with the use of the high potency products which are now being used, and perhaps a pause in states approving or further legalizing the product until we know more. We are seeing emergency room visits increasing, and patients are not expecting the adverse health events that are occurring.

Welcome Sponsor And Newsletter

Alli 0:27

Have you provided anesthesia care for a patient who uses cannabis? Are you asking patients about cannabis use during your pre-operative evaluation? Here are some of the important physiological effects from cannabis use that anesthesia professionals need to be aware of: altered drug metabolism, airway hyperreactivity, increased postoperative pain, and be on the lookout for cardiovascular instability and unpredictable sedative requirements. Stay tuned as we explore this topic further on the show today. Hello, and welcome back to the Anesthesia Patient Safety Podcast. I'm your host, Ali Bechtel, anesthesiologist and podcast host. Before we dive further into the episode today, we'd like to recognize Vertex, a major corporate supporter of APSF. Vertex has generously provided unrestricted support to further our vision that no one shall be harmed by anesthesia care. Thank you, Vertex. We wouldn't be able to do all that we do without you. Our featured article is from the February 2026 APSF newsletter. That's right, we are opening up the newest newsletter, and there are some excellent articles to talk about. Our featured article is Cannabis and Anesthesia, a 2025 update on perioperative considerations by Dylan Irving and colleagues. To follow along with us, head over to APSF.org and click on the newsletter heading. The first one down is the current newsletter. Then you can scroll down until you get to our featured article today. And I will include a link in the show notes as well. To help kick off the show today, we are going to be hearing from one of the authors. Here she is now.

SPEAKER_00 2:17

Hi, my name is Trisha Meyer. I'm a Pharm D and an adjunct professor of anesthesiology at the Texas AM College of Medicine. I also serve as a co-chair for the Anesthesia Patient Safety Foundation Medication Safety Advisory Group. I am also an APSF member of the editorial board and the Committee on Education and Training.

Alli 2:44

I asked Trisha why she is so passionate about this topic. Let's take a listen to what she had to say.

SPEAKER_00 2:51

This topic is very important for several reasons. With 40 states allowing medical marijuana and 24 states allowing recreational marijuana, the use of THC, which is the principal psychoactive cannabinoid, has skyrocketed. 18 million Americans report daily or near daily use of the product. Additionally, the pot used from the 1960s, the 1970s, and up to the 1990s is nothing like the highly concentrated product we see in use today. With potency quadrupling or even more.

Pharmacology THC CBD And Receptors

Drug Interactions And CYP Effects

Preop Screening And When To Delay

Intraop Dosing Evidence And Airway

Postop Pain Withdrawal And Takeaways

Alli 3:49

Thank you so much, Tetricia, for helping to set the stage. Almost four years ago, we first talked about the perioperative considerations for cannabis use during anesthesia care. This was episodes number 108 and 109. We are bringing you updated considerations today, and this update is timely since adult cannabis use in the United States has increased considerably with the expansion of state legislation. By mid-2025, medical cannabis is authorized in 40 states, the District of Columbia, and several U.S. territories. And recreational adult use is legal in 24 states and DC. Along with the increased use, there has also been an increase in research in this area to help guide anesthetic management. Let's start the conversation with pharmacological considerations. We need a quick review and some definitions first. The phytocannabinoids include THC or tetrahydrocannabinol and CBD or cannabidiol. These are the most commonly known botanical cannabinoids. THC is the main psychoactive compound in the cannabis fativa plant, which is one of the most commonly occurring subspecies. CBD is the active cannabinoid but not mind-altering. So how does this drug work? Cannabinoids bind to cannabinoid receptors type 1 and type 2 in the body. These receptors are part of the endocannabinoid system and located throughout the body and brain. The endocannabinoid system is responsible for regulating learning and memory, emotional processing, sleep, temperature control, pain control, inflammatory and immune response, and appetite. The CB1 receptor is involved in the nervous system, motor function, memory, analgesia, and others. The CB2 receptor is involved with anti-inflammatory and pro-inflammatory reactions. Endogenous endocannabinoid stimulation of the CB1 receptors does not cause the same level of euphoria that may be seen following THC or marijuana use. Endocannabinoids undergo rapid breakdown by enzymes. For all of our runners out there, some researchers have suggested that the runner's high, that feeling of bliss and well-being during a run, may be due to the release of endocannabinoids rather than from endorphins. Phytocannabinoids may act as partial agonists, full agonists, or antagonists at the cannabinoid receptors. Plus, downregulation of these receptors can occur with partial agonist effects from THC that can lead to tolerance and decreased effects. Therapeutic actions of THC and CBD include the following analgesic, antiametic, anti-inflammatory, anti-seizure, and neuroprotection. The method of administration is important for drug effects and plasma levels. Inhaling or smoking cannabis has a rapid onset with THC detected in plasma within seconds. After five to seven minutes of smoking with 10 to 15 milligrams THC, the peak plasma levels will be 100 mics per liter. Metabolites will appear in the urine and feces as glucurinide conjugates with some of the urine metabolites lasting for up to two weeks. Acute THC or THC CBD intoxication may have the following signs and symptoms: increased disinhibition, impaired memory, and impairments in learning, attention, attentional bias, and psychomotor function. Adverse effects may be mild to severe and depend on the drug concentration, route of administration, and prior exposure. These include euphoria, anxiolysis, tachycardia, sensory amplification, postural hypotension, conjunctivitis, hunger, dry throat, mouth, and eyes. More serious side effects may include panic attacks, myoclonus, psychosis, hyperemesis, hypertension, tremors, seizures, inhalation burns, hallucinations, unconsciousness, acute respiratory distress syndrome, and bronchospasm. There can be ongoing and long-term effects that persist even after stopping use. Drug-drug interactions may occur with THC with effects on absorption, metabolism, excretion, or pharmacodynamic effects. The action of THC may be intensified or dampened by some prescription drugs, and the opposite effects may occur. Pharmacological action and side effects of prescription drugs may be affected by THC. The most common serious drug-drug interactions with cannabis and cannabinoids are warfarin, valproate, tachyrolimus, and serrolimus, with reported adverse events including bleeding, altered mental status, higher anesthetic requirements, and gastrointestinal distress. There is a good resource for clinicians to determine possible drug-drug interactions between cannabinoids and common prescription medications. It is a free online tool, www.ca nir.psu.edu. I will include the link in the show notes so that you can check it out. The interactions between THC and CYP inhibitors and inducers are notable as well. CYP inhibitors may increase the bioavailability of THC and increase the desired or the unwanted side effects. CYP inducers may decrease the effects of THC. Check out Table 1 in the article for a list of common CYP inhibitors and inducers. Next up, we are going to discuss the peroperative considerations. Table 2 is an excellent resource with all of the considerations related to cannabis use for anesthesia professionals. This would be a good teaching resource for anesthesia trainees or a discussion at your next anesthetic department meeting. Let's start with the preoperative period. It is important to obtain a history of cannabis use and document the type of products, route and frequency, dose, time of last use, and presence of withdrawal symptoms. You can also ask about the use of cannabis with other products, including alcohol, opioids, or sedatives, and if any adverse reactions have occurred. This information can help identify cardiovascular and respiratory risks, possible withdrawal, delayed gastric emptying from THC, and anesthetic challenges during intoxication. Cannabis use is associated with higher rates of perioperative complications, including cardiorespiratory events and wound-related issues. There is evidence that cannabis use shortly before surgery may increase the risk for myocardial infarction, especially in patients with coronary artery disease. Elective surgery may need to be delayed, and for patients with symptoms or high-risk patients, further cardiac workup may be necessary. When patients present with acute intoxication, with anxiety, paranoia, or psychosis, elective surgery should be delayed until patients are sober. For patients seen in a pre-op anesthesia clinic prior to surgery, advice should be given about temporary cessation of cannabis, document use in the medical record, and consider options for postoperative analgesic management. At this time, there are no strong evidence-based guidelines for how long to discontinue cannabis use prior to surgery. Once you're in the operating room, be on the lookout for higher anesthetic requirement. Regular cannabis use may increase propofol dose required for induction and procedural sedation. Patients may require higher doses of IV and volatile agents to achieve adequate anesthetic depth. There is the potential for drug-drug interactions that may blunt or potentiate the effects of cannabis, especially with sympathometics, vasoactive agents, and CYP inducers and inhibitors. It is important to monitor for cardiopulmonary complications and be prepared to treat. Patients who inhale cannabis are at risk for increased airway reactivity and bronchospasm. Patients with acute intoxication are at the highest risk for emergence agitation and hemodynamic instability. Research has been done in this area to help inform our anesthetic management for cannabis users. There are two meta-analyses with eight studies and over 2,000 patients, and with 11 studies and over 4,000 patients that demonstrated increased requirements for IV anesthetics, especially propofol, for cannabis users undergoing general anesthesia and sedation. Two retrospective studies revealed increased requirements for inhalational anesthetics as well. There is a recent prospective study that reported significantly higher doses of sedative agents, including fentanyl, midazlam, and propofol, for marijuana users. We are looking forward to more research in this area going forward to help guide formal clinical recommendations. In the recovery room, there are additional considerations since patients may have higher postoperative pain scores and increased opioid consumption. Multimodal analgesia and non-opioid adjuncts are important for adequate pain control. Patients may develop symptoms of withdrawal from cannabis use, which presents as irritability, nausea, anxiety, and sleep disturbance. Withdrawal may occur one to two days after last use, and symptoms can last for one to two weeks. There are reports of postoperative hypothermia and shivering among cannabis users, and this may be due to type 1 receptor activity instead of from withdrawal. Let's do a quick review of the perioperative considerations. Pre-op, screen for cannabis use and assess cardiovascular, respiratory, and withdrawal risks. Interop, utilize individualized dosing, careful monitoring, and be prepared for hemodynamic or airway complications. Post-op, anticipate increased analgesic requirements, plan for multimodal analgesia, and monitor for withdrawal symptoms. There is a call to action for anesthesia professionals to stay informed of new data related to cannabis use to optimize perioperative safety and anesthesia care. Before we wrap up for today, we are going to hear from Trisha again. I also asked her what she hopes to see going forward. Here is her response.

SPEAKER_00 15:13

And patients are not expecting the adverse health events that are occurring.

Questions Subscribe And Share

Alli 15:19

Thank you so much, Tricia, for contributing to the show today. If you have any questions or comments from today's show, please email us at podcast at apf.org. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit apf.org for detailed information and check out the show notes for links to all the topics we discussed today. That's it for today's episode. If this conversation sparked a thought or gave you something to take back to your practice and your department and your colleagues, make sure that you're subscribed so you don't miss future episodes. You can listen wherever you get your podcasts, and sharing the show with a colleague really helps to spread the word about improving patient safety in anesthesia. Thanks for listening. Until next time, stay vigilant so that no one shall be harmed by anesthesia care.