Many medications and supplements must be stopped days or weeks before surgery to reduce bleeding risk, prevent drug interactions with anesthesia, and avoid surgical complications. Your surgical team will provide specific instructions, but understanding the reasons behind these changes helps you prepare safely.
Blood Thinners and Antiplatelet Medications
Warfarin (Coumadin): Typically stopped 5 days before surgery to allow your INR (a measure of clotting ability) to return to normal range (below 1.5 for most surgeries). Your surgeon and cardiologist will decide whether bridging therapy with injectable heparin is needed during this gap, based on your clot risk.
Direct oral anticoagulants (DOACs) such as apixaban (Eliquis), rivarelbaan (Xarelto), and dabigatran (Pradaxa): Usually stopped 2 to 3 days before surgery, depending on your kidney function. Patients with reduced kidney function may need to stop 4 to 5 days before because these drugs are cleared more slowly.
Aspirin: Low-dose aspirin (81 mg) is continued through many surgeries, especially cardiac and vascular procedures. For other surgeries, your surgeon may ask you to stop 7 to 10 days before. Never stop aspirin without asking your prescriber, as abrupt discontinuation in cardiac patients can trigger rebound clotting events.
Clopidogrel (Plavix) and prasugrel (Effient): Stopped 5 to 7 days before surgery. If you have a coronary stent placed within the past 12 months, stopping these drugs carries significant risk. Your cardiologist and surgeon must coordinate the timing carefully.
Supplements and Over-the-Counter Products
Fish oil (omega-3 fatty acids): Stop 7 to 10 days before surgery. Fish oil inhibits platelet aggregation and can increase surgical bleeding. At supplemental doses (1000 to 4000 mg per day), the antiplatelet effect is clinically meaningful.
Vitamin E: Stop 7 to 10 days before surgery when taking doses above 400 IU per day. High-dose vitamin E has mild antiplatelet and anticoagulant effects that can increase bleeding during and after surgery.
Herbal supplements to stop at least 2 weeks before surgery: ginkgo biloba (increases bleeding), St. John's wort (interacts with anesthesia drugs and many medications by inducing liver enzymes), garlic supplements (antiplatelet effect at high doses), ginseng (may cause hypoglycemia and interacts with blood thinners), and kava (potentiates sedation from anesthesia).
NSAIDs (ibuprofen, naproxen): Stop 7 days before surgery unless your surgeon instructs otherwise. These inhibit platelet function for the life of the platelet (7 to 10 days). Acetaminophen (Tylenol) does not affect platelets and can be used for pain up to the day of surgery.
Diabetes and Metabolic Medications
Metformin: Typically stopped 24 to 48 hours before surgery. Metformin can cause lactic acidosis in the rare setting of kidney stress from surgery, dehydration, or contrast dye used in imaging. Resume when you are eating normally and kidney function is confirmed stable (usually 48 hours post-surgery).
Insulin: Your endocrinologist or surgical team will provide a modified dosing plan. Long-acting insulin (glargine, detemir) is usually continued at a reduced dose (typically 50% to 80% of your normal dose the night before and morning of surgery). Rapid-acting insulin (lispro, aspart) is held on the morning of surgery since you will not be eating.
SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin): Stop 3 to 4 days before surgery. These drugs can cause euglycemic diabetic ketoacidosis (DKA with normal blood sugar), a dangerous condition that is difficult to detect because blood glucose appears normal. The risk is elevated during the stress and fasting of surgery.
Sulfonylureas (glipizide, glyburide): Hold on the morning of surgery to prevent hypoglycemia (low blood sugar) while fasting. Resume when eating regularly after surgery.
Medications That Should NOT Be Stopped
Most blood pressure medications: Continue beta-blockers, ACE inhibitors, ARBs, and calcium channel blockers through surgery unless your anesthesiologist specifically instructs otherwise. Abruptly stopping beta-blockers can cause rebound hypertension and rapid heart rate, which is dangerous during surgery.
Thyroid medications (levothyroxine): Continue on your normal schedule. Take with a small sip of water on the morning of surgery, even if you are fasting. Thyroid hormone has a long half-life, so missing one dose is not dangerous, but maintaining the routine is preferred.
Anti-seizure medications: Never stop without neurologist guidance. Abrupt discontinuation can trigger breakthrough seizures. Take with a small sip of water on the morning of surgery.
Psychiatric medications (SSRIs, SNRIs, mood stabilizers, antipsychotics): Generally continue through surgery. Abrupt discontinuation of SSRIs can cause withdrawal syndrome. Lithium may be held the morning of surgery due to interactions with anesthesia and kidney sensitivity, but only under psychiatrist guidance. Always inform your anesthesiologist of all psychiatric medications.
Frequently asked
Questions patients ask.
How do I remember which medications to stop and when?
Ask your surgeon's office for a written pre-operative medication instruction sheet at your pre-op visit. Create a calendar counting backward from your surgery date, marking when each medication should be stopped. For example, if surgery is on a Monday, warfarin stops the prior Wednesday (5 days), and fish oil stops 10 days before (the Friday of the week before that). Set phone reminders for each stop date.
I forgot to stop my blood thinner before surgery. Will my surgery be cancelled?
Possibly. Your surgeon will check your coagulation labs on the day of surgery. If your clotting values are outside the safe range, elective surgery is typically postponed to reduce bleeding risk. Emergency or urgent surgeries may proceed with additional precautions (reversal agents, extra blood products on standby). Always call your surgeon's office as soon as you realize you forgot, even if it is the day before surgery.
Can I take Tylenol for pain in the days before surgery when I have stopped my other medications?
Yes, in most cases. Acetaminophen does not affect blood clotting and is safe before surgery at standard doses (up to 3000 mg per day for adults, or 2000 mg per day for patients over 65 or with liver conditions). Confirm with your surgeon, but acetaminophen is the go-to option when NSAIDs and aspirin must be avoided pre-operatively.
Should I bring my medications to the hospital on surgery day?
Yes. Bring all current medications in their original labeled bottles, including prescriptions, over-the-counter drugs, and supplements. The anesthesia team will review them for potential interactions. Some hospitals have you take specific home medications with a sip of water the morning of surgery (such as blood pressure and anti-seizure medications). Having the actual bottles prevents any confusion about drug names, doses, and timing.
For patients
Get a personalized care plan.
This guide provides general information. For instructions tailored to your specific procedure, ask your provider about QR Rx care plans.
These medication guides are for educational purposes only and do not replace medical advice. Always follow your healthcare provider's specific medication instructions.
