Preparing for Surgery
“There is no safer place in the world to have an anaesthetic than in Australia.”
Australian Society of Anaesthetists 2007
Preparation for Anaesthesia and Surgery
Risks and Side Effects of Anaesthesia
Anaesthesia is generally very safe, but like any medical treatment it can have side effects and risks.
Common side effects (usually mild and temporary):
- Drowsiness or feeling sleepy
- Dizziness
- Nausea or vomiting
- Sore throat or a hoarse voice (from a breathing tube used while you are asleep)
- Pain or discomfort after the operation (your anaesthetist will help manage your pain)
Rare but more serious complications include:
- Allergic reactions to anaesthetic drugs
- Damage to teeth during airway management
- Breathing difficulties
- Awareness during the operation
- Heart attack or stroke
The overall risk from anaesthesia depends on several factors, including your general health, medical conditions and type of surgery you are having. Your Specialist Anaesthetist is highly trained to manage these risks and to keep you safe during your procedure.
If you would like to discuss any aspect of your anaesthetic or these risks, please speak with your anaesthetist. You can also contact our administration staff, who can arrange for you to speak with the appropriate anaesthetist if needed.
In general, we advise patient to stop smoking and vaping before your operation. Heart and lung problems should be stabilised prior to surgery. If you are concerned about these please contact your Surgeon or Anaesthetist.
Medications before surgery
Most regular medications (below) can be continued as usual before surgery. However, some medications require adjustment while you are fasting or may need specific instructions depending on the type of surgery you are having. If you are unsure about any medication, please contact your anaesthetist or surgeon for advice. Medications that are commonly continued include;
- Blood pressure and heart disease medications
- Antidepressants
- ADHD medications
- Asthma medications and inhalers
- Anti-epileptic (seizure) medications
- Parkinson’s disease medications
- Thyroid medications
- Cholesterol-lowering medication
In most cases, you should continue taking your usual medications with a small sip of water.
Diabetic Medications
Management of diabetes medications change while you are fasting. Unless you have been given specific instructions by your surgeon, anaesthetist or endocrinologist, the table below outlines the management of common diabetic medications before an operation.
| Medication Type | Examples | When to stop before surgery |
| Oral Hypoglycaemics | Metformin, Gliclazide, Sitagliptin, Pioglitazone | Stop while fasting |
| SGLT 2 Inhibitors | Dapagliflozin, Empagliflozin | Stop 2 days before surgery |
| GLP-1 Medications | Ozempic, Wegovy, Saxenda, Trulicity, Mounjaro, Trulicity | Continue as usual but you need to have a clear fluid diet 24 hours before your operation (see below) |
| Long-acting Insulin | Lantus, Toujeo, Levemir | Take normal dose the night before surgery (none on the morning of surgery) |
| Short-acting Insulin | Actrapid, Novorapid, Humalog, Apidra | Stop while fasting |
In general, do not take insulin while fasting before surgery unless instructed to by your anaesthetist or endocrinologist.
If you are unsure or have any questions about how to manage diabetic medications before your operation, please contact your anaesthetist or surgeon.
Blood thinners and anticoagulants
Blood-thinning medications include aspirin, clopidogrel (Plavix), warfarin, apixaban (Eliquis), rivaroxaban (Xarelto) and dabigatran (Pradaxa).
For larger or higher-bleeding-risk operations (e.g. joint replacement, major abdominal surgery, spinal or neurosurgery), these medications are commonly withheld for some days before surgery. Apixaban, rivaroxaban and dabigatran are typically ceased 2-3 days prior to surgery to reduce the risk of bleeding. If required, clopidogrel and warfarin may be withheld for longer (5-7 days).
Please contact your surgeon or anaesthetist for specific instructions regarding your blood-thinning medications.
Anti-inflammatories and supplements
Anti-inflammatory medications include ibuprofen (Nurofen), diclofenac (Voltaren), meloxicam
(Mobic) and celecoxib (Celebrex) amongst others.
- For most simple or day-only procedures, these can usually be continued
- For some procedures (such as ENT, orthopaedic or neurosurgery), you may be asked to stop them beforehand
Herbal supplements and over-the-counter products may also affect bleeding. If you are unsure whether to continue or stop any of these medications, please clarify with your surgeon or anaesthetist.
Fasting before surgery
It is important to have an empty stomach at the time of surgery. Food or fluid in the stomach can be vomited and may enter the lungs while you are unconscious, which can be life threatening.
General fasting rules
No food or solids for 6 hours before surgery. Clear fluids may be taken up until 2 hours before surgery.
Clear fluids include:
Water, clear juice, cordials, electrolyte/sports drinks, black tea or black coffee, broth
Milk is not a clear fluid – it solidifies in stomach acid and behaves like food.
In practice:
Morning surgery:
No food or milk after midnight. Clear fluids up until 2 hours prior to admission.
Afternoon surgery:
A light breakfast before 7:00 am (e.g. tea and toast). No further food, but clear fluids up until 2 hours prior to admission.
Fasting for Patients taking GLP-1 medications
(e.g. Ozempic, Mounjaro, Wegovy, Saxenda, Trulicity)
These medications slow stomach emptying. You do not need to stop them before surgery, however, you must;
Follow a clear-fluid-only diet for 24 hours before your operation
From 6 hours before your operation small volume clear fluids only (<200ml/hr)
Stop all fluids from 2 hours before your operation
If you do not know your operation time, then please use your admission time instead
Please note that these are general guidelines. You may be given specific fasting instructions by your surgeon or anaesthetist that differ from the above – please follow those instructions. If you are unsure, contact your anaesthetist for advice.
On the Day of Surgery and After Surgery
Your Anaesthetist will visit or contact you to assess you and make certain it is safe to proceed with your anaesthetic. Your Anaesthetist will ask relevant questions regarding your health, the surgical procedure and the anaesthesia required. This is a good opportunity for you to ask any remaining questions.
In the Operating Theatre
Your Anaesthetist will remain with you in the Operating Theatre for the entire duration of the procedure. He/she will administer the appropriate anaesthetic for your procedure, ensuring your safety while the operation proceeds and will supervise your recovery.
Going Home and Beyond
If you are having day surgery, make sure that you have someone to take you home. Additionally, you need to be in the company of another responsible person overnight. For the first 24 hours AFTER your day surgery you must not drive, drink alcohol, operate machinery, make important decisions or sign any legal documents.
It is normal to have some pain, nausea and fatigue after surgery and anaesthesia. Depending on your operation and other medical conditions, you may be sent home with some prescriptions, e.g. antibiotics, pain relief and nausea medication. If you are concerned about your post-operative symptoms, please contact your anaesthetist or surgeon for further instructions, or visit your GP.