Patients who do not tell their surgical team they are using weight-loss injections or unapproved peptides could face serious consequences, according to RNZ, reporting a new study that found an 11-fold risk of regurgitation or aspiration in GLP-1 users under general anesthetic.

The drugs are GLP-1 receptor agonists, sold as Ozempic, Wegovy and Mounjaro, which mimic a natural hormone and keep people feeling full for longer. They also slow digestion, which is exactly the problem here: a standard pre-surgery fast may not leave the stomach empty.

Why an empty stomach matters

Under anesthetic, the reflexes that normally protect the airway stop working. "Food or fluid in there can come back up and then slip into the airway and lungs, and that can cause serious lung injury," Australian and New Zealand College of Anaesthetists president Tanya Selak told RNZ, adding that the event is rare but is the reason fasting is routine at all.

The numbers behind the warning

The study, published last month in the peer-reviewed journal Anaesthesia, looked at more than 47,000 patients across the UK and identified almost 1,350 who had been taking GLP-1 drugs in the three months before surgery. That group was 11 times more likely to regurgitate or aspirate than patients not on the medications.

Most cases involved regurgitation only, and most happened as patients woke up. The authors are careful to note the link is not necessarily causal, since obesity and diabetes already raise aspiration risk on their own, and that caveat deserves to survive the headlines intact.

The pause nobody can justify

Around a third of patients in the study were told to stop their medication for a week beforehand. Professor Michael Horowitz of Adelaide University called that advice "demonstrably stupid," because slowed gastric emptying can persist well beyond a week, and pausing a GLP-1 carries its own risks for people managing type 2 diabetes.

His real point is the uncomfortable one: "People are getting mixed advice because we don't have a good evidence base to give advice." ANZCA currently recommends clear fluids for 24 hours followed by a standard six-hour fast, and that anesthetists ask the GLP-1 question directly.

Why people stay quiet

Selak says patients hide it because they forget, feel embarrassed, or bought something unapproved. Weight stigma is doing a lot of the damage here, and so is the gym-floor supply chain: she described patients who report no medications at all, then eventually mention a peptide injection someone handed them.

Bottom line

Australia has an estimated half a million GLP-1 users, plus a quieter population self-injecting unapproved compounds such as retatrutide. The risk signal is now measured, the right pre-surgery protocol is not, and Horowitz wants research on how long gastric emptying stays slowed after a dose.