The Practical Rule
Keep taking most regular medicines unless told not to — but never guess with blood thinners or diabetes drugs.
Bring a full list of everything you take — prescriptions, over-the-counter tablets, vitamins, herbs, injections, and weight-loss meds — to pre-admission or on the day.
Usually Continue
Take with a small sip of water on the morning of surgery
- Asthma inhalers / puffers
- Thyroid tablets
- Anti-seizure medicines
- Steroids
- Reflux medication
- Most heart / blood pressure medicines
Usually Stop or Check First
Do not stop these on your own — follow your surgeon/anaesthetist/GP advice
- Blood thinners (see below)
- Diabetes medicines (see below)
- Anti-inflammatories (ibuprofen, naproxen, diclofenac)
- ACE inhibitors / ARBs (often withheld day of surgery)
- Herbal supplements & vitamins
- Weight-loss medications
Blood Thinners
Follow your surgeon's advice regarding blood thinners. The timing depends on why you take it, your kidney function, the type of surgery, and whether a spinal/epidural is planned.
- Warfarin
- Apixaban, Rivaroxaban, Dabigatran (newer blood thinners)
- Clopidogrel (antiplatelet)
- Aspirin — sometimes continued, sometimes stopped
Do not stop these on your own unless your surgeon, anaesthetist, or GP has told you to.
Diabetes Medicines
Diabetes medicines are the most important to get right before surgery.
See our comprehensive Diabetes & Surgery guide →
SGLT2 Inhibitors
Dapagliflozin (Forxiga), Empagliflozin (Jardiance) — stop 3 days before surgery. Risk of perioperative ketoacidosis.
Other Oral Diabetes Tablets
Usually taken as normal the day before, then omitted on the day of surgery.
Insulin
Usually reduced rather than stopped. The exact dose depends on whether you have type 1 or type 2 diabetes and whether you are fasting. Your anaesthetist or endocrinologist will advise.
GLP-1 Medicines
Ozempic, Wegovy, Trulicity, Mounjaro — current Australian guidance (ANZCA/ADS/GESA/NACOS) says routine stopping is not recommended. Instead:
- Have a 24-hour clear fluid diet the day before the procedure
- Then follow standard fasting guidelines
- Make sure your anaesthetic team knows you are taking it
Reference: 2025 ADS/ANZCA/GESA/NACOS Clinical Practice Recommendations
Anti-Inflammatories & Painkillers
Anti-inflammatory medicines such as ibuprofen, naproxen, diclofenac may need to be stopped because they can affect bleeding.
Some specialties are very cautious about these — Ear Nose & Throat and Neurosurgery in particular. Whereas Orthopaedics and Urology may have different views, and may even encourage you to continue aspirin.
Follow your surgeon's advice — they have to deal with the bleeding.
ACE Inhibitors & ARBs
Medicines like perindopril, ramipril, irbesartan, telmisartan, candesartan are often withheld on the day of surgery because they can contribute to low blood pressure under anaesthesia. This is not universal.
If you have a blood pressure monitor, use it. Most anaesthetists would rather you take your blood pressure tablets — hypertension is more problematic, and your anaesthetist is aware of the intraoperative risks and can manage low blood pressure if required.
Herbal Supplements & Vitamins
Many hospital guidelines recommend stopping herbal supplements 2 weeks before surgery. Common ones that can affect bleeding or anaesthesia:
- Garlic supplements
- Ginkgo
- Ginseng
- Fish oil / Omega-3
- St John's Wort
It is especially important to tell your anaesthetist about antidepressants, diabetes medicines, and blood thinners.
Diabetes & Surgery Guide | Fasting Guidelines
Phone: (02) 4228 5055 | Email: iass@iass.net.au