The warning comes as the use of GLP-1-based drugs – which mimic a natural hormone to help people feel full for longer – continues to rise rapidly in Australia, with an estimated half a million people using them. Authorities have also reported people self-injecting unapproved GLP-1 drugs such as retatrutide.
Because these medications slow digestion, standard pre-surgery fasting may not be sufficient to empty a patient's stomach, increasing the risk of pulmonary aspiration – when food or fluid enters the airways and lungs – while under anaesthetic. Dr Tanya Selak, President of the Australian and New Zealand College of Anaesthetists (ANZCA), said that while aspiration is rare, it can cause serious lung injury or be fatal.
"When you're under anaesthetic, your body's automatic safety reflexes like coughing and swallowing are switched off so food or fluid in there can come back up and then slip into the airway and lungs," Dr Selak said.
Some patients fail to disclose their use of the drugs because they have forgotten, are embarrassed, or are trying to conceal the purchase of unapproved peptides, the college said. "That weight stigma can be very strong. They do worry that by disclosing these private personal details that they might be judged or they might be treated differently," Dr Selak added.
A study published last month in the peer-reviewed journal Anaesthesia, examining more than 47,000 patients, found that those on GLP-1s were 11 times more likely to regurgitate or aspirate contents under general anaesthetic compared to those not taking the medications. Doctors have already been delaying surgery or using alternative anaesthetic methods because of the known risk.