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Managing regular medications before surgery
Most regular medications are continued until the morning of surgery, and only those that add real risk in anaesthesia are stopped: SGLT2 inhibitors (ketoacidosis), GLP-1 agonists (full stomach), ACE inhibitors and ARBs (hypotension), anticoagulants, and drugs that clash with anaesthetic drugs.
Why it matters in the exam
The exam asks when SGLT2 inhibitors are stopped and why, what the guidance is for GLP-1 agonists, whether ACE inhibitors are continued on the day of surgery, what is done with metformin and insulin, what MAOIs and lithium mean in anaesthesia, why levodopa must not be stopped and which antiemetics are forbidden in Parkinson disease, who needs steroid supplementation, and what is done with herbal remedies and contraceptive pills.
Beta blockers, statins, calcium channel blockers, inhalers, antiepileptic drugs, thyroid drugs, psychiatric drugs and levodopa are continued. Stopping levodopa causes rigidity, swallowing problems and a picture similar to neuroleptic malignant syndrome, and in a Parkinson patient metoclopramide, droperidol and haloperidol are avoided. ACE inhibitors and ARBs are usually omitted on the morning of surgery (or 24 hours before) in a patient without heart failure, because they cause hypotension that is hard to treat under anaesthesia. According to the FDA from 2020, SGLT2 inhibitors are stopped at least 3 days before elective surgery (ertugliflozin — 4 days), because they may cause ketoacidosis with near-normal glucose. GLP-1 agonists slow gastric emptying: in 2023 it was advised to omit the weekly dose a week before, and the joint guidance from 2024 allows continuing in most patients, with a liquid diet 24 hours before in high-risk patients and consideration of gastric ultrasound. Metformin is omitted on the day of surgery, and basal insulin is reduced by about 20% on the evening before.
MAOIs may cause serotonin syndrome with pethidine and dextromethorphan, and a hypertensive crisis with indirect drugs such as ephedrine; so if they are continued, direct drugs such as phenylephrine are used in small doses. Lithium prolongs the action of muscle relaxants and is toxic in dehydration, so it is usually stopped 24–72 hours before major surgery. A patient taking prednisolone at 5 mg or more a day for more than 4 weeks may develop adrenal insufficiency during surgery, and so receives hydrocortisone 100 mg at induction for major surgery. Herbal remedies such as ginkgo, garlic and ginseng increase bleeding, and St John's wort speeds drug breakdown; they are usually stopped two weeks before. Combined pills and hormone therapy raise the risk of thrombosis, and in major surgery with prolonged bed rest stopping them 4 weeks before or giving thromboprophylaxis is considered. Anticoagulants and antiplatelet drugs have separate guidance.
Key points
- Most drugs are continued.
- SGLT2: stop 3 days before; GLP-1: usually continue with a liquid diet in high risk.
- ACE and ARB: omit on the morning of surgery without heart failure.
- MAOI: no pethidine or ephedrine; lithium prolongs muscle relaxants.
- Chronic steroids: hydrocortisone 100 mg at induction in major surgery.
Summary table
| Drug | What is done | Exam point |
|---|---|---|
| Beta blockers, statins, inhalers, antiepileptic drugs | Continue | Stopping a beta blocker causes tachycardia and ischaemia |
| ACE inhibitors and ARBs | Omit on the morning of surgery in a patient without heart failure | Hypotension that is hard to treat |
| SGLT2 inhibitors | Stop 3 days before (ertugliflozin — 4) | Ketoacidosis with near-normal glucose |
| GLP-1 agonists | 2024: continue in most patients, a liquid diet for 24 hours in high risk | Full stomach and aspiration |
| Metformin and insulin | Metformin — not on the day of surgery; basal — reduce by about 20% | Avoid low glucose |
| MAOIs and lithium | MAOIs: no pethidine or ephedrine; lithium: stop 24–72 hours | Phenylephrine instead of ephedrine |
| Levodopa | Continue, also by nasogastric tube | No metoclopramide or droperidol |
| Steroids | 5 mg or more for more than 4 weeks: hydrocortisone 100 mg at induction | Adrenal insufficiency |
In the full version for subscribers
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Sources
- ESC Guidelines on cardiovascular assessment and management of patients undergoing non-cardiac surgery, 2022 — Perioperative pharmacological management
- US FDA Drug Safety Communication on SGLT2 inhibitors, 2020 — Stopping before scheduled surgery
- Multisociety clinical practice guidance on GLP-1 receptor agonists before procedures, 2024 — Continuation and liquid diet
- Association of Anaesthetists guideline on glucocorticoids in the perioperative period, 2020 — Steroid supplementation
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.