Can You Smoke Weed Before Surgery?

How Marijuana Affects Anesthesia and Surgery

You should not smoke weed before surgery. Like nicotine, marijuana can complicate surgery, impact how quickly you get out of the hospital, and delay healing. You should avoid it in the weeks and even months before your procedure. 

This article explains how marijuana can interfere with surgery and why abstaining from it is part of the pre-surgery recommendations you'll get from your healthcare provider.

Benefits of Quitting

Researchers know that marijuana use prior to surgery can potentially interact with anesthesia. In addition, it can lead to breathing difficulties and increased pain.

Much like the benefits of quitting cigarettes before surgery, quitting marijuana also has benefits. Abstaining from marijuana in the weeks before surgery can decrease the likelihood of complications.

Unfortunately, research on the topic of marijuana use and its effects during surgery is limited. That's because the federal government still classifies marijuana as a Schedule I substance. That classification limits the ability to do adequate research on its use.

As the legalization of medical and recreational marijuana increases, it will be easier to gather scientific data on the topic.

Types of Marijuana

Before surgery, you should avoid all types of marijuana. That means you should not smoke it, eat edibles, or use synthetic marijuana.

Smoking Risks

If your use involves regularly smoking marijuana, it may lead to the same risks of complications as smoking cigarettes. Therefore, marijuana smokers may be more likely than non-smokers to experience:

  • Being on the ventilator longer
  • Having a higher risk of developing pneumonia after surgery
  • Greater scarring of incisions

Contrary to popular wisdom, marijuana smoking is not a healthier alternative to cigarettes. On the contrary, it can increase the risk of lung cancer and other respiratory problems.

The chronic coughing, wheezing, and difficulty breathing that long-term cigarette smokers experience also occur in marijuana users. 

The process of inhaling marijuana, then holding it in the lungs for extended periods to increase absorption, leads to increased exposure to cancer-causing chemicals.

effects of marijuana on the lungs

Verywell / Brianna Gilmartin

Marijuana and Anesthesia

Studies have found that those who use marijuana before surgery require more anesthesia than those who do not. So, it's important to discuss your use with your healthcare provider before surgery to ensure you receive adequate sedation.

Synthetic marijuana, in particular, is unregulated and poorly understood. The contents are also highly variable. For these reasons, it is impossible to predict how it might interact with anesthesia.


The use of marijuana, especially immediately before surgery, can change the doses needed for sedation. A person who routinely uses marijuana requires substantially higher doses of one commonly used medication, propofol.

One study looked at the doses of propofol required to intubate people who routinely smoked marijuana compared with those who did not. Those who used marijuana required a dramatic increase in sedation.

Airway Obstruction

One case study looked at a person who smoked marijuana four hours before surgery. The patient experienced an airway obstruction during the procedure—a severe complication that can lead to death. 

Researchers believed airway hyperreactivity was the cause. This condition, in which the airway spasms and narrows, is known in cigarette smokers but was not previously reported in marijuana smokers.

Interactions with Anesthesia Drugs

THC (delta-9-tetrahydrocannabinol), which is the main active ingredient of cannabis, is a central nervous system (CNS) depressant. That means it can further slow brain activity if used in combination with medications such as benzodiazepines, narcotics, or other sedative hypnotic drugs.

Aspiration Risk

THC can also slow gastric function, causing a significant delay in how quickly food leaves the stomach. This may increase the risk of aspiration during anesthesia.

Any food or liquid that enters a person's airway can lead to choking, respiratory complications, and infection.

It is unlikely that your marijuana use will delay your surgery, but it is essential that the anesthesiologist knows about it. They need to understand the chance that your body will need more anesthetic than is typical.

Marijuana and the Vascular System

If you use marijuana the day before surgery, especially the hours before the procedure, it can cause more dramatic effects. That's because of the impact that cannabis and surgery have on your blood vessels.

Marijuana causes the blood vessels of the body to relax. This process is called vasodilation. It can cause lower blood pressure and increased heart rate.

These changes, in turn, can complicate matters if a person's blood pressure falls during surgery. In addition, it can change the way the body responds to anesthesia.

After Surgery

Marijuana use can impact how you recover from surgery. For example, studies have indicated that marijuana affects ventilator (breathing machine) usage and pain after surgery.


Regularly smoking marijuana, like smoking cigarettes and cigars, can increase the length of time a person needs to stay on the ventilator after surgery. 

You can decrease the chances of being on the ventilator for a longer time by quitting smoking before surgery. The more time that passes between your last day of smoking and surgery, the lower your risk.

Increased Pain

In a study of 118 people who had surgery for a broken leg, researchers compared those who had used marijuana before surgery to those who did not. Researchers presented the findings at their 2020 annual meeting of the American Society of Anesthesiologists.

The researchers found that those who used marijuana:

  • Required more anesthesia
  • Reported significantly higher pain scores after surgery
  • Received 58% more opioids for pain management while they recovered in the hospital

Withdrawal Symptoms

Regular and heavy marijuana use may cause withdrawal symptoms. These can begin one to two days after the last time someone takes the drug.

These symptoms may include:

  • Irritability
  • Anxiety
  • Trouble sleeping
  • Fatigue
  • Decreased appetite

Talk to Your Healthcare Provider

You must be truthful with your healthcare provider about your personal use of marijuana. Be sure to give them an accurate account of how much, how often, and how you consume it.

Honestly disclosing your marijuana use will allow healthcare professionals to watch for known risks and help them make the best decisions about your anesthesia and pain management.


Marijuana use can increase the risks of surgery. These risks include requiring more anesthesia, experiencing more pain, and trouble with breathing, blood pressure, and heart rate.

Stopping marijuana use before surgery is the best way to avoid these risks. The sooner you quit before surgery, the greater the benefit.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.