Pre-op guidance › Medicines before surgery

Your medicines before surgery

Your usual medicines may need to be adjusted before surgery to keep you safe. Always bring your medicines, or a complete list, to hospital, including tablets, inhalers, patches and injections.

The easiest way to check your medicines is the planner.
Enter your surgery date and your medicines and it tells you exactly when to take your last dose, with a printable list and calendar dates.

Open the medicine timing planner →

If you are unsure about any medicine, ask. Always follow the specific instructions from Dr Halvey, your surgeon, the pre-admission clinic, your GP or your specialist, as your plan may differ.

The list below is a reference if you would rather read it. For most people, the planner above is quicker.

Blood pressure medicines

ACE inhibitors and ARBs
Examples: perindopril (Coversyl), ramipril (Tritace), lisinopril (Zestril), irbesartan (Avapro), valsartan (Diovan), candesartan (Atacand), telmisartan (Micardis), losartan (Cozaar).
Instruction: withhold for 24 hours before surgery (do not take on the morning of surgery).

Beta-blockers
Examples: atenolol (Tenormin), metoprolol (Betaloc, Lopresor), bisoprolol (Bicor), propranolol (Inderal).
Instruction: continue as normal, including the morning of surgery.

Calcium channel blockers
Examples: amlodipine (Norvasc), diltiazem (Cardizem), verapamil (Isoptin).
Instruction: continue as normal.

Diuretics
Examples: frusemide (Lasix), hydrochlorothiazide, indapamide (Natrilix), spironolactone (Aldactone).
Instruction: withhold on the morning of surgery to reduce dehydration and low blood pressure.

Blood thinners

Warfarin (Coumadin, Marevan)
Usually stopped 5 days before surgery. May need "bridging" with injections.

Direct oral anticoagulants (DOACs)
Examples: apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), edoxaban (Lixiana).
Usually stopped 2 to 3 days before surgery (longer if kidney function is reduced).

Antiplatelets
Examples: clopidogrel (Plavix), ticagrelor (Brilinta), prasugrel (Effient).
Usually stopped 5 to 7 days before surgery.
Aspirin (Cartia, Astrix): usually continued.

Diabetes medicines and insulin

These are general instructions for adults having surgery or a procedure with sedation or anaesthesia. Please follow any specific instructions given to you by your anaesthetist, surgeon, pre-admission clinic, GP, endocrinologist or diabetes educator.

If you have type 1 diabetes, use an insulin pump, have frequent low blood glucose, or have unstable diabetes control, please contact us before surgery for an individual plan.

Diabetes tablets

Take your usual diabetes tablets up to and including the night before surgery, unless told otherwise.
Do not take diabetes tablets on the day of surgery.
Restart them when you are eating and drinking normally, unless told otherwise.

SGLT2 inhibitors ("flozins")

Some diabetes, heart failure and kidney medicines need to be stopped earlier because they can increase the risk of ketoacidosis around surgery. This can occur even when the blood glucose level is not very high.

Stop SGLT2 inhibitors for 3 days before your procedure. This means do not take them on the two days before surgery or on the day of surgery. For example, if your surgery is on Friday, your last dose should be on Tuesday.
Examples include: Jardiance, Forxiga, Steglatro, Xigduo / Xigduo XR, Jardiamet, Glyxambi, Qtern / Qternmet, Segluromet and Steglujan.
Do not restart until you are eating and drinking normally and are not unwell. Ask for advice before restarting if you have nausea, vomiting, abdominal pain, infection, dehydration or ketones.

Short-acting or meal-time insulin

Do not take short-acting or meal-time insulin while fasting, unless you have been given a specific correction-dose plan. Examples include: NovoRapid, Fiasp, Humalog, Apidra and Actrapid.

Long-acting basal insulin

Do not stop basal insulin completely unless you have been specifically told to do so. If you take long-acting basal insulin, take 50% of your usual dose at the usual time from the evening before surgery until your procedure, unless you have been given different instructions. Examples include: Optisulin / Lantus, Toujeo, Tresiba, Levemir and Semglee. For example, if you normally take 20 units, take 10 units.

Intermediate-acting insulin

If you take intermediate-acting insulin, such as Protaphane or Humulin NPH, take 50% of your usual dose at the usual time, unless you have been given different instructions.

Premixed insulin and Ryzodeg

Premixed and co-formulated insulins contain both a meal-time and a longer-acting component, so the dose needs adjusting when you are fasting. Examples include: NovoMix 30, Ryzodeg 70/30, Humalog Mix, Mixtard 30/70 and Humulin 30/70.

The evening before surgery: take 80% of your usual evening dose. For example, if you normally take 30 units, take 24 units.
Morning surgery (before 1 pm): do not take your morning premixed insulin or Ryzodeg while fasting. Check your blood glucose when you wake and bring your insulin and glucose monitor to hospital.
Afternoon surgery (after 1 pm): have an early light breakfast as instructed by the hospital, and take 50% of your usual morning dose with breakfast. For example, if you normally take 30 units, take 15 units. After breakfast, do not take any more premixed, Ryzodeg or meal-time insulin while fasting.
Lunchtime dose: if you normally take one, do not take it while fasting unless told otherwise.
After surgery: restart your usual routine when eating and drinking normally, unless your team tells you otherwise.

Insulin pumps

Do not stop or suspend an insulin pump unless you have been given an alternative insulin plan. Please contact us before surgery for specific pump instructions.

GLP-1 medicines (Ozempic, Wegovy, Mounjaro, Trulicity and similar)

If you are taking one of these medicines before surgery, you will need to follow special fasting rules, because they slow stomach emptying.

24 to 6 hours before surgery: clear fluids only.
6 to 2 hours before: water only (maximum 200 ml per hour).
2 hours before: nothing by mouth.

Clear fluids include water, black tea or coffee (no milk), clear apple juice, electrolyte drinks or clear broth. Avoid milk, smoothies, protein shakes, creamy soups, or juices with pulp.

If you did not follow these instructions, please tell us, as your surgery may be delayed or modified. Some conditions (for example gastroparesis, Parkinson's, or bowel problems) may also slow stomach emptying even with correct fasting. Please let us know.

Read the full GLP-1 before surgery guidance →

Cholesterol medicines

Statins - atorvastatin (Lipitor), rosuvastatin (Crestor), simvastatin (Zocor), pravastatin (Pravachol): continue as normal.
Other cholesterol-lowering medicines - ezetimibe (Ezetrol), fenofibrate (Lipanthyl): continue.

Antidepressants and anti-anxiety medicines

Examples: sertraline (Zoloft), escitalopram (Lexapro), venlafaxine (Efexor), amitriptyline (Endep). Instruction: continue.

Epilepsy medicines

Examples: valproate (Epilim), carbamazepine (Tegretol), levetiracetam (Keppra). Instruction: continue.

Inhalers for asthma or COPD

Examples: Ventolin, Seretide, Spiriva. Instruction: continue, and bring them to hospital.

Steroids

Examples: prednisone, dexamethasone, hydrocortisone. Instruction: do not stop suddenly. You may need extra "stress doses" during surgery.

Pain medicines

Paracetamol: continue as normal.
Anti-inflammatories (NSAIDs) such as Nurofen, Voltaren, Mobic: usually stopped before surgery due to bleeding and kidney risk.
Opioids such as Endone, Targin, Tramadol: continue if prescribed.

Supplements and herbal remedies

Fish oil, vitamin E, garlic, ginkgo, ginseng, St John's Wort: stop at least 7 days before surgery.

Download PDF