When facing surgery, many questions arise, including how personal habits might affect the procedure. As cannabis use becomes more common, both recreationally and medically, understanding its impact on surgical outcomes is increasingly important for patient safety. The various compounds in cannabis, primarily tetrahydrocannabinol (THC) and cannabidiol (CBD), interact with the body’s systems in ways that can alter the experience before, during, and after a medical procedure.
How Cannabis Affects Your Body Before Surgery
Cannabis interacts with several bodily systems, influencing a patient’s response to surgery and anesthesia. Smoked or vaped cannabis can irritate the respiratory system, leading to wheezing, coughing, and chronic bronchitis. This irritation complicates breathing tube placement for anesthesia and increases airway hyperactivity risk. Some research suggests that the bronchial tissue damage from 3-4 cannabis cigarettes daily can be comparable to that from 20 tobacco cigarettes.
The cardiovascular system is also affected; cannabis can increase heart rate and blood pressure at lower to moderate doses. Conversely, higher doses can lead to a slower heart rate and decreased blood pressure. There is also an increased risk of heart attack, particularly within the first hour after cannabis use, especially for those with existing heart conditions.
Cannabis also impacts the central nervous system; its psychoactive components can induce sedation or heightened anxiety. If a patient is acutely intoxicated, there is a greater chance of violent emergence from anesthesia. Beyond these direct effects, THC is primarily metabolized in the liver by the cytochrome P450 complex, a pathway shared with many anesthetic drugs. This shared metabolic pathway can lead to pharmacokinetic interactions, potentially altering anesthetic medication effectiveness.
Risks During and After Your Procedure
Cannabis’s physiological effects can lead to specific complications during and after surgery. Regular cannabis users often require significantly higher doses of anesthetic agents (e.g., propofol, sevoflurane, midazolam) for adequate sedation.
Some studies indicate cannabis users may need 50% to 220% more anesthesia, increasing the risk of insufficient sedation or awareness if dosages are not adjusted. Beyond anesthesia, cannabis use can affect bleeding risk. THC can inhibit liver enzymes involved in drug metabolism, impacting the breakdown of blood thinners like warfarin and potentially increasing bleeding risk.
Healthcare providers may need to evaluate coagulation function before surgery for cannabis users. Post-operative pain management presents another challenge. Despite perceptions that cannabis alleviates pain, studies show users frequently report higher pain scores after surgery and require more opioid analgesics.
This can lead to increased opioid consumption. Cannabis users may also face a higher likelihood of postoperative nausea and vomiting. While certain cannabinoid compounds treat chemotherapy-induced nausea, THC extract has not been shown effective for preventing post-surgical nausea and vomiting and can have unpredictable side effects. Smoking cannabis can also increase the risk of respiratory complications following surgery. For edible consumers, delayed gastric emptying can occur, similar to eating or drinking before surgery, raising aspiration risk.
Cannabis withdrawal symptoms can emerge post-operatively, typically starting 1-2 days after last use and lasting one to two weeks. These symptoms, including irritability, sleep disturbances, restlessness, and nausea, can complicate recovery and might be mistaken for other medical issues.
Recommendations for Cannabis Users Before Surgery
Specific guidelines for cannabis cessation before surgery are still evolving, with no universal standard. However, several recommendations are commonly provided to minimize risks. For those who smoke or vape cannabis, some sources suggest discontinuing use at least 72 hours (three days) before a procedure. Other recommendations advise a minimum of 12 hours. If a patient has acute cannabis intoxication or a high risk of coronary artery disease, elective surgery should be delayed until these conditions resolve, potentially for an hour or more after use.
For edible cannabis products, effects last longer due to liver metabolism. It is often recommended to stop edibles significantly earlier than smoked forms, with some guidance suggesting up to four weeks prior to surgery due to heavy liver processing. However, other sources suggest a minimum of 12 hours. This longer abstention is partly due to concerns about delayed gastric emptying, which poses an anesthesia risk.
Patients who use cannabis for medical purposes should discuss their specific regimen with their healthcare team. Abruptly stopping certain prescribed cannabinoid-derived medications (e.g., dronabinol or Epidiolex) is generally not advised and should be medically supervised. For chronic users, a gradual reduction in cannabis consumption, or “weaning,” starting at least 14 days before surgery, may be more appropriate than abrupt cessation to mitigate withdrawal symptoms.
Why Full Disclosure is Essential
Open and honest communication with the healthcare team is crucial for patient safety when considering cannabis use before surgery. Providing comprehensive information about cannabis use (type, frequency, last use) allows the medical team to make informed decisions. This transparency enables surgeons and anesthesiologists to adjust anesthesia protocols, plan for pain management challenges, and anticipate withdrawal symptoms.
Healthcare professionals prioritize patient well-being and rely on accurate information to tailor the safest care plan. Patients should feel confident that disclosing cannabis use ensures their safety and optimizes surgical outcomes, not judgment or legal repercussions, as this information is confidential. Since patients may not meet their anesthesiologist until surgery day, informing the surgeon’s office in advance about cannabis use is a proactive step.