Doctors in Spain are warning that the extreme heat marking the start of summer, combined with the growing use of GLP-1 weight-loss drugs such as Ozempic, is putting patients at greater risk of dehydration.
Gontrand López-Nava, an expert in techniques against obesity, said the effects of the drugs, added to those caused by heatwaves, could end up dehydrating patients and creating a health problem. Ozempic is the best known drug in the GLP-1 family, a class of medicines originally developed for type 2 diabetes that has become widely used for weight loss because it acts on the brain to curb appetite.
López-Nava said the combination of high temperatures with the now widespread use of weight-loss drugs deserves caution so as not to create other health problems. He said the drugs act on the brain to reduce appetite and, in some cases, also reduce thirst, ultimately lowering the intake of both solid food and liquids. He said that when this is added to the excess heat of summer, scenarios of dehydration can occur.
Nausea, vomiting and other side effects
López-Nava said these situations can be compounded by the well known side effects of GLP-1 drugs, including nausea, vomiting, poor digestion, a sustained feeling of fullness and changes in bowel rhythm that can appear as either diarrhoea or constipation. All of these effects reduce the intake of liquids and food, he said, and in the case of vomiting and diarrhoea they also increase the loss of water and electrolytes.
In summer, with extreme temperatures, this combination can encourage significant dehydration if hydration measures are not stepped up, said López-Nava, who directs the Bariatric Endoscopy Unit at Hospital Universitario HM Sanchinarro.
He said it is not only the heat that drives fluid loss through sweat. Many patients treated with GLP-1 drugs drink less, eat less and can also present digestive symptoms that make adequate hydration harder to achieve. He described it as a combination that calls for special vigilance during the summer months.
Heatwave deaths in Spain
Spain's first heatwave of the year has caused numerous deaths and cases of what are known as heatstroke. López-Nava said the danger is greater for patients who are taking weight-loss drugs to fight obesity, because these conditions combine.
He said that when there is extreme heat, the loss of water and electrolytes increases, which is why proper hydration matters so much. He said that if heat is combined with physical exercise to lose weight, the use of weight-loss drugs, and a reduced intake of food and water, the result is a very dangerous combination that the public needs to bear in mind.
Among other problems, López-Nava said dehydration can cause acute kidney failure, high blood pressure, fainting or electrolyte disorders. He called for responsibility and urged patients to consider alternatives to the drugs as summer continues, pointing to the increasingly popular option of bariatric endoscopy, a technique that treats obesity through the digestive tract without open surgery.
Five recommendations for patients
López-Nava set out five recommendations for patients taking GLP-1 drugs.
- Keep up adequate hydration even without feeling thirsty
- Avoid intense exercise during the hottest hours of the day
- Moderate alcohol consumption
- See a doctor if persistent vomiting, diarrhoea or an inability to stay properly hydrated appear
- Do not use these medications without medical guidance and follow-up
He said taking weight-loss drugs is not a cure-all. He described them as only an aid to changing habits, one that has to be used consciously, in a controlled way and with professional follow-up.
López-Nava directs the Bariatric Endoscopy Unit at Hospital Universitario HM Sanchinarro. He has been credited with changing the approach to treating obesity by building nutritional and psychological follow-up into bariatric endoscopy procedures.
