Many patients have other preoperative co-morbidities (e.g., hypertension, diabetes, etc.) and are taking certain medications. Often, when the anesthesiologist visits the patient before surgery, he or she finds that the patient is taking certain medications and the surgery has to be postponed. Many patients do not understand or even hide the medication they are taking because they are afraid to postpone the surgery, thinking they can get away with it, not knowing that this leaves a huge hidden danger for the safety of surgical anesthesia and may cause serious consequences. So, why do you stop taking certain medications before surgery? Should all medications be discontinued prior to surgery? Anesthesia provides a guarantee for the smooth performance of surgery, not only in ensuring that patients are pain-free during surgery, but more importantly, in ensuring that patients’ blood pressure and heart rate are stable throughout the surgery. Most anesthetic drugs affect patients’ blood pressure and heart rate, while many patients’ daily medications increase the risk of surgical patients, adding difficulties to clinical management and endangering patients’ lives. Patients taking digitalis drugs (digoxin, cetiran, etc.) for heart failure and atrial fibrillation should stop taking them on the day of surgery. Diuretics (dihydroketuria, tachyphylaxis, butalbital, etc.), antiarrhythmics (cardioplegia, isoptin, etc.), and anti-anginal drugs (nitroglycerin, cardiac pain, betalactam, cardiac pain, etc.) should be taken with a small sip of water until the morning of the surgery. It is recommended to check electrolytes the day before surgery for serum K+ levels. Patients taking antihypertensive medications should take them until the morning of the day of surgery. However, three classes of anti-hypertensive drugs require special attention. ①Patients taking lispro (e.g., antihypertensive 0) will have difficulty raising their blood pressure with the medication if there is hemorrhage or hypotension during surgery, leading to serious consequences. They should stop taking the medication for 1 week before surgery and switch to other antihypertensive medications at the same time. Patients taking potassium-removing diuretics (hydrochlorothiazide, furosemide, etc.) are prone to hypokalemia, which can induce arrhythmia or even cardiac arrest during anesthesia, and are generally discontinued for 2-3 days before surgery. It is recommended to check electrolytes and know the serum K+ level one day before surgery. ③Patients taking alpha-blockers (e.g., terazosin) may experience iris relaxation syndrome during cataract surgery, so patients should inform their physicians of this drug prior to surgery. Aspirin and clopidogrel are commonly used in patients with coronary artery disease, myocardial infarction, stroke, and interventional procedures (e.g., stent implantation) to reduce the risk of cardiovascular accidents and to prevent postoperative thrombosis. It should be continued perioperatively in patients after coronary stenting if they undergo surgery within 6 weeks of bare stent implantation and 12 months of drug-eluting stent implantation. In patients without coronary stents, preoperative discontinuation of aspirin for 1-2 weeks (preferably two weeks) and clopidogrel for 1 week if not discontinued or in emergency patients, intravesical anesthesia should be avoided. For some procedures where small amounts of bleeding have serious consequences (intracranial surgery, intraocular surgery, intravertebral surgery, etc.), clopidogrel can be discontinued for 1 week and ticlopidine (resorcinolide) for 2 weeks prior to surgery. Warfarin is mainly used for the prevention of deep vein thrombosis and for patients who need long-term maintenance anticoagulation after heart valve replacement, and the drug should be stopped for 4-5 days before surgery. Heparin is commonly used for perioperative venous thromboembolism prophylaxis and has no antiplatelet properties and does not prevent in-stent thrombosis. It is usually continued until the time of surgery, and low molecular heparin should be discontinued for at least 12 hours prior to surgery. Thrombolytic/fibrinolytic drugs have a very high risk of bleeding; absolutely avoid intralesional anesthesia and apply peripheral nerve blocks with caution depending on the site of the block. Patients who have been using oral hypoglycemic drugs and medium- and long-acting insulin for a long time should be switched to short-acting insulin therapy 1-3 days before surgery. Due to preoperative fasting and water fasting, all hypoglycemic drugs should be discontinued on the day of surgery to avoid causing hypoglycemia. Patients taking monoamine oxidase inhibitors (e.g., eugenol) and tricyclic antidepressants (e.g., amitriptyline, doxepin, etc.) should stop taking them 2-3 weeks before surgery. Patients taking antithyroid hormones and antiepileptic drugs (phenytoin sodium) should be applied until the morning of the surgery day. Some herbs contain ingredients that can interact with anesthetics or other medications and are potentially dangerous to surgical patients; all herbs need to be discontinued for at least 24 hours prior to surgery. All types of medications that can be taken on the day of surgery, except for slow-release agents, etc., all medications are recommended to be crushed and taken with a small sip of water 1 —-2 hours before surgery. In conclusion, patients who have been taking medications for a long time should give a detailed description of their medications to the doctor before elective surgery so that the doctor can make medication adjustments through a comprehensive assessment of the patient’s condition to ensure the safety of the surgical patient.