What to Tell Your Anesthesiologist Before Surgery

If you’re about to receive general anesthesia for a medical procedure, you may have a lot on your mind. You may be distracted filling out the requisite paperwork that asks what medications you take and whether you drink, smoke cigarettes, or use marijuana. You might even downplay your answers for fear of what they might say about you.

While it’s never a good idea to keep health information from your physician in general, it’s critical that you try to be as thorough and honest as possible in answering their health questions before receiving anesthesia. Marijuana use, cigarette smoking, vaping, and taking certain medications, such as anti-obesity drugs, including semagultide (Wegovy®) and tirzepatide (Zepbound®), can all affect your anesthesia plan.

“Most patients will tell you everything, but they can also misremember the types and dosages of medications they’re taking. And often, they don’t know that not every medical practice shares medical records,” says Jill Zafar, MD, a Yale Medicine anesthesiologist. “With a car, you can look up your VIN number and see every piece of material that's ever been put into it. But even in the same health system, all medical records aren’t necessarily the same, which means we rely on the patient to provide this information to us. That’s why it’s important to provide your anesthesiologist with a complete list of everything you are taking."

Typically, you won’t meet your anesthesiologist until the day of your procedure. That’s when you would discuss your list of medications and supplements. However, the doctor who referred you for your medical procedure will typically ask for this information in advance and provide any necessary instructions to the anesthesiology team.

“And although it’s not routinely scheduled, patients can always ask to speak to an anesthesiologist ahead of time if they have questions,” Dr. Zafar says.

Below, we talk more with Dr. Zafar about how various substances, habits, and supplements can affect anesthesia.

General anesthesia involves treatment with medication to make you unconscious so that your body is still and you don’t feel pain during surgery. Heart surgery, organ transplants, back surgery, and many other long operations require general anesthesia.

Typically, the medications are administered through intravenous (IV) therapy. Because general anesthesia can affect breathing, the anesthesiologist may insert a tube into your windpipe to help you breathe better during the procedure.

Because marijuana use has become legal for medical and recreational purposes in many states, Dr. Zafar says she is encountering more patients who use it.

“What’s confounding about marijuana is that it comes in many different formulations. It can be smoked, vaped, or it can be an edible. Some people are on medical marijuana, and it's prescribed,” Dr. Zafar says. “And marijuana today has a much higher portion of THC [tetrahydrocannabinol, the psychoactive ingredient in marijuana that produces a high] than it used to, which makes it more potent.”

There are also cannabidiol (CBD) supplements, often in the form of chewable gummies, notes Dr. Zafar. CBD is a chemical found in marijuana that does not contain THC.

All these different formulations can make it difficult for an anesthesiologist to plan around, Dr. Zafar says. “We want patients to tell us what form of marijuana—and how much—they are using, so we can understand the potency,” she says. "This is important because it can affect how well the anesthesia works. You may actually have more of a tolerance to anesthesia, which means you need more of it.”

While doctors continue to research the effects of marijuana and CBD on a patient’s surgical risks and their recovery, the American Society of Anesthesiologists says enough is known to warrant certain precautions before and after surgery. For example, patients are advised not to use any marijuana product on the day of surgery.

If a patient does smoke on the day of surgery, it should be at least two hours before the procedure, according to the American Society of Regional Anesthesia and Pain Medicine, because smoking marijuana can “significantly increase heart rate and blood pressure within the two hours following use, and it may increase the patient’s risk of suffering a surgery-related heart attack.”

It's also unclear when it’s safe to resume marijuana use following surgery. “It can depend on the patient’s medical history and the type of surgery they had,” says Dr. Zafar.

Smoking cigarettes and vaping nicotine are harmful to the lungs, and the effects of either can linger for up to six weeks after stopping their use, Dr. Zafar notes. “So, ideally, you would want to stop six weeks before your surgery,” she says.

When someone smokes, their lungs don’t work as well as they should, which can lead to an increased risk of complications during general anesthesia. For example, smokers are at an increased risk of bronchospasm (when the airways in the lungs tighten, leading to low oxygen levels). If that happens while someone is under anesthesia, that could cause pneumonia, Dr. Zafar says.

“Smoking also increases your chance of a heart attack during or after surgery, and it reduces blood flow, which can limit wound healing,” Dr. Zafar says. “Smoking can also make you cough, which can irritate any incisions and increase your risk of bleeding.”

Dr. Zafar acknowledges that some people smoke to relieve anxiety, and she doesn’t want them to be overly nervous on the day of surgery. However, if they can’t quit well in advance of surgery, she advises that they at least refrain from smoking for several hours beforehand. “After just a couple of hours of not smoking, your ability to carry oxygen around your body goes up,” she says.

When it comes to alcohol use, Dr. Zafar says it’s important for patients to be upfront about how much they drink. As with marijuana, alcohol can impact how you respond to anesthesia.

“If someone is physically dependent on alcohol or has alcohol use disorder, they may actually require more anesthetic,” Dr. Zafar says. But, she says, it’s not a good idea to stop drinking suddenly before their procedure, because that could mean they go into withdrawal two to three days after surgery.

“Alcohol withdrawal can be serious; someone can have seizures, high blood pressure, a rapid heartbeat, and even a heart attack. If you just had surgery and then go into withdrawal, it heavily increases your risk of postoperative complications,” she says. “If patients tell us about their alcohol use prior to surgery, we can treat them with medications that can reduce their risk of going into withdrawal, and we’ll be on heightened alert if their anesthesia needs to be adjusted.”

Knowing this information in advance can also allow the medical team to offer the patient instructions on how to wean off alcohol ahead of surgery. “When people are dependent on alcohol, coming in for surgery might be the first time they’ve stopped drinking for a prolonged period of time, and many patients don't even realize this,” Dr. Zafar says. “We want people to know that if they are open and honest, we can help take better care of them.”

If someone is taking opioids for chronic pain or certain conditions, it should be on their medication list. But if someone has opioid use disorder (OUD) and is taking large amounts of medications or has a history of OUD, that can affect how they react to anesthesia.

“Sometimes with chronic use, someone may require more anesthesia as their pain response may be more sensitive. But it’s variable, and it’s helpful for us to know what they are on,” Dr. Zafar says. “And if they are on a medical treatment for OUD, such as buprenorphine, often known as Suboxone®, we would come up with a pain management plan around that.”

Medications used to treat obesity and type 2 diabetes, such as semaglutide (sold, respectively, under brand names Wegovy® and Ozempic®) and trizepatide (sold under brand names Mounjaro® and Zepbound®) can also affect your anesthesia plan.

These medications, Dr. Zafar says, have properties that delay gastric emptying, or the time it takes for food to move through the stomach and into the small intestine. When you undergo anesthesia, your stomach should be empty, because otherwise, you could regurgitate undigested food and cause aspiration, which happens when food, liquid, or other materials enter the airways. Aspiration can lead to pneumonia.

In 2023, the American Society of Anesthesiology issued a guidance statement about the use of these medications, also known as GLP-1s (glucagon-like peptide-1). The society says that patients who do daily dosing should consider not taking a dose on the day of the procedure. For patients who do weekly dosing, they should consider not taking their dose at least seven days before the surgery.

All patients who undergo general anesthesia are asked if they have sleep apnea, which causes people to stop breathing periodically while asleep.

Because general anesthesia can suppress upper airway muscles, it can slow down your breathing rate and decrease oxygen levels, which can be dangerous for someone with sleep apnea.

“These patients can be at increased risk for complications, particularly respiratory-related ones, after surgery. If you have sleep apnea, the effects of the anesthetic medications on your respiratory status are more pronounced,” Dr. Zafar says. “As a result, for certain surgeries where you would typically leave the same day, we might decide to keep you overnight to make sure your breathing is OK.”

Patients with sleep apnea who use a CPAP machine should bring their mask with them to use in the recovery room, Dr. Zafar adds.

The Food and Drug Administration (FDA) regulates dietary supplements under a different set of regulations than those covering "conventional" foods and drug products, which means they are not reviewed by the agency before they go on the market.

“Many supplements come from reputable companies and you can generally rely on what they say is in them, but you can’t be 100% sure, so it’s important to tell us what you’re taking. We recommend everyone stop taking their supplements a week before surgery just to be safe,” Dr. Zafar says. “Supplements can have varying effects on our bodies and can interact with medications given in the perioperative period—for instance, some, such as ginseng, garlic, or vitamin E, can increase your risk of bleeding.”