What Interferes with Anesthesia? A Guide to Medications and Lifestyle Factors

In one survey, 22% of patients undergoing surgery reported using herbal medicine, yet most fail to disclose this to their healthcare providers [1.3.2]. Understanding what interferes with anesthesia is critical for preventing complications and ensuring a safe surgical outcome.

Quick Summary

A comprehensive overview of medications, supplements, and lifestyle choices that can interfere with anesthesia. It covers specific drugs, herbs, and habits like smoking or drinking that pose risks during surgery.

Key Points

• Full Disclosure is Vital: Always inform your surgical team about all medications, supplements, and lifestyle habits to prevent complications [1.2.1].

• Blood Thinners Pose Bleeding Risks: Prescription anticoagulants, NSAIDs (like ibuprofen), and certain herbs (garlic, ginkgo) must be stopped before surgery [1.2.2].

• Diabetes & Weight Loss Drugs Need Management: Medications like Metformin and Ozempic require special instructions due to risks of low blood sugar and aspiration [1.2.5, 1.2.8].

• Herbal Supplements Are Not Harmless: Many herbs can interfere with bleeding, blood pressure, or prolong sedation; stop them 2-3 weeks before surgery [1.3.6].

• Lifestyle Choices Matter: Smoking and alcohol use significantly increase surgical risks, including poor wound healing, infection, and altered anesthesia response [1.4.3].

• Pre-existing Conditions Increase Risk: Sleep apnea, heart disease, obesity, and a family history of anesthesia reactions must be discussed with your anesthesiologist [1.5.3, 1.5.4].

• Mental Health Meds Can Interact: MAOIs in particular can have dangerous interactions with anesthetic drugs and need to be stopped weeks in advance [1.2.2].

The Critical Importance of Full Disclosure

Before any surgical procedure, your anesthesiologist undertakes the immense responsibility of keeping you safe, comfortable, and stable. The success of this task depends heavily on the accuracy of the information you provide. A wide array of substances and pre-existing conditions can significantly alter how your body responds to anesthetic drugs [1.2.1]. Even seemingly harmless over-the-counter pills or natural supplements can have potent effects, from increasing bleeding risk to causing dangerous fluctuations in heart rate and blood pressure [1.2.2, 1.3.8]. Being completely transparent about your health history, medication use, and lifestyle habits is not just a formality—it's a crucial component of your safety [1.2.4].

Prescription Medications: A Primary Concern

Many chronic conditions require daily medication, but some of these necessary drugs can pose risks during surgery. It's vital to discuss every prescription with your surgical team, as they will provide specific instructions on which to continue and which to temporarily stop [1.2.1].

Key Medication Classes of Interest

• Blood Thinners (Anticoagulants and Antiplatelets): Medications like warfarin (Coumadin), clopidogrel (Plavix), apixaban (Eliquis), and even daily aspirin dramatically increase the risk of bleeding during and after surgery. Your surgeon will provide a specific timeline for stopping these, which can be several days to a week before the procedure [1.2.2]. Stopping them is essential, as patients on anticoagulants may be unable to receive certain types of regional anesthesia like epidurals [1.2.2].
• Diabetes Medications: Drugs such as metformin, insulin, and GLP-1 agonists (Ozempic, Wegovy) require careful management. Since patients must fast before surgery, dosages are often adjusted to prevent dangerously low blood sugar [1.2.1]. GLP-1 agonists also delay stomach emptying, which increases the risk of aspirating stomach contents while under anesthesia. The American Society of Anesthesiology recommends stopping weekly doses a week before surgery and daily doses on the day of the procedure [1.2.5, 1.6.3].
• Blood Pressure and Heart Medications: While some blood pressure drugs like beta-blockers are often continued, others like ACE inhibitors may be held for 24 hours before surgery to prevent blood pressure from dropping too low [1.2.8].
• Mental Health Medications: Antidepressants, particularly Monoamine Oxidase Inhibitors (MAOIs), can interact severely with anesthetic agents and must be stopped 1-2 weeks prior [1.2.2, 1.2.4]. Other psychiatric medications like SSRIs are often continued to prevent withdrawal, but the anesthesiologist must be aware of them to anticipate potential altered responses to anesthesia [1.2.2].
• Weight Loss Drugs: Medications containing phentermine are stimulants that can affect heart rate and blood pressure, and are typically stopped several days before surgery [1.2.8].

Over-the-Counter (OTC) Drugs and Supplements

Many people underestimate the power of non-prescription products. Herbal remedies and supplements are biochemically active compounds that can cause significant complications [1.3.2]. The American Society of Anesthesiologists suggests discontinuing all herbal medications 2 to 3 weeks before surgery [1.3.6].

Common Culprits to Avoid:

• NSAIDs: Ibuprofen (Advil, Motrin) and naproxen (Aleve) can increase bleeding risk, similar to prescription blood thinners [1.2.2].
• Herbs Affecting Bleeding: A large group of popular supplements can thin the blood or inhibit clotting. These include Garlic, Ginger, Ginkgo Biloba, Ginseng, Fish Oil, Vitamin E, and Turmeric [1.2.2, 1.2.4].
• Herbs Affecting Sedation: Some herbs have sedative properties that can dangerously prolong the effects of anesthesia. Valerian root, Kava, and St. John's Wort are notable examples. St. John's Wort also interferes with drug metabolism, which can unpredictably alter the potency of anesthetic drugs [1.2.2, 1.3.4, 1.3.8].
• Herbs Affecting the Cardiovascular System: Ephedra (Ma Huang) acts as a stimulant and can lead to dangerous heart and blood pressure issues during surgery [1.2.4].

Substance Category	Examples	Primary Anesthetic Risk	Recommended Action (Consult Doctor)
Blood Thinners	Warfarin, Plavix, Xarelto, Aspirin, Ibuprofen	Increased risk of serious bleeding [1.2.2]	Stop 5-7 days before surgery as advised [1.2.6].
Diabetes Meds	Metformin, Insulin, Ozempic, Jardiance	Hypoglycemia; Risk of aspiration [1.2.5, 1.2.8]	Adjust dose or hold medication as per instructions [1.2.1].
Sedative Herbs	Valerian, Kava, St. John's Wort	Prolonged sedation; Unpredictable drug metabolism [1.3.4]	Discontinue at least 2 weeks before surgery [1.3.6].
Stimulant Herbs	Ephedra (Ma Huang), Ginseng	Increased heart rate and blood pressure [1.2.4]	Discontinue at least 2 weeks before surgery [1.3.6].
Lifestyle Factors	Smoking, Heavy Alcohol Use	Impaired healing, altered drug metabolism, infection risk [1.4.3, 1.4.4]	Stop smoking and drinking at least 4 weeks prior [1.4.2].

Lifestyle Factors and Medical Conditions

Your daily habits and overall health profile are just as important as the medications you take.

Habits that Interfere with Anesthesia:

• Smoking: Nicotine use thickens the blood, impairs wound healing by reducing oxygen delivery, and increases the risk of postoperative lung complications [1.4.3, 1.4.7]. It's recommended to quit at least 4 weeks before surgery [1.4.2].
• Alcohol Use: Chronic heavy drinking can damage the liver, which is crucial for metabolizing anesthetic drugs [1.4.3]. It can also lead to requiring higher doses of anesthesia, increase bleeding risk, and raise the chance of postoperative infections [1.4.4, 1.4.6].
• Recreational and Cannabidiol (CBD) Products: Marijuana and CBD use can affect heart rate, blood pressure, and pain control during and after surgery. Full disclosure is essential [1.2.1].

Key Medical Conditions:

Certain health issues increase the risk of complications. These include:

• Obstructive Sleep Apnea: Can cause breathing difficulties during and after anesthesia [1.5.3].
• Heart and Lung Disease: Conditions like high blood pressure, heart failure, asthma, or COPD require careful anesthetic management [1.5.4].
• Obesity: Increases the risk of multiple complications [1.5.4].
• History of Adverse Reactions: A personal or family history of malignant hyperthermia (a severe reaction to anesthesia) is critical to report [1.5.3].

Conclusion: Your Role in a Safe Surgery

Ultimately, the safety of your anesthesia rests on a partnership between you and your medical team. The most effective way to mitigate risks is through open and honest communication. Before your procedure, prepare a complete list of every single substance you take—prescriptions, OTC drugs, vitamins, herbs, and recreational products—and review it with your surgeon and anesthesiologist [1.2.1]. Answering questions about your lifestyle habits truthfully allows the anesthesia team to create a tailored plan that anticipates potential interactions and keeps you safe. Your diligence before surgery is your best defense against complications.

For more information, consider resources from the American Society of Anesthesiologists.

Frequently Asked Questions

How long before surgery should I stop taking herbal supplements?

The American Society of Anesthesiologists recommends stopping all herbal medications at least two to three weeks before an elective surgical procedure to prevent potential complications [1.3.6].

Can I take ibuprofen for a headache before my surgery?

No, you should avoid ibuprofen (Advil, Motrin) and other NSAIDs before surgery as they can increase your risk of bleeding. They are typically stopped about a week prior to the procedure [1.2.2].

Do I need to tell my anesthesiologist if I smoke marijuana or use CBD?

Yes, it is crucial. Use of marijuana or CBD products can affect your heart rate, blood pressure, and the amount of anesthesia you may need. Honest disclosure is essential for your safety [1.2.1].

I have diabetes. What should I do about my medication on the day of surgery?

You must discuss your diabetes medication plan with your primary doctor and surgeon. Since you will be fasting, your dosages for drugs like metformin or insulin will likely need to be adjusted or held to prevent low blood sugar [1.2.1, 1.2.2].

Why is alcohol use a concern before surgery?

Alcohol can thin your blood, increasing bleeding risk. Chronic use can also affect how your body metabolizes anesthetic drugs and increase your susceptibility to infections after surgery [1.4.4, 1.4.7].

What is the biggest risk with weight loss medications like phentermine before anesthesia?

Weight loss medications that are stimulants, like phentermine, can increase your heart rate and blood pressure. This can have an unwanted stimulating effect when combined with anesthesia, complicating blood pressure management during the procedure [1.2.8].

Is it safe to continue my blood pressure medication before surgery?

It depends on the medication. Beta-blockers are often continued, but others like ACE inhibitors may be stopped 24 hours prior. You must get specific instructions from your doctor for your particular medication [1.2.8].