As the UK experiences a heatwave with record highs of 34°C in London and the South East, health warnings have been issued for users of weight loss medications such as Ozempic and Mounjaro. Dr Suzanne Wylie, a GP and medical advisor for IQdoctor, warns that these injections could create additional health concerns in warm weather.
Why Are Weight Loss Drugs Risky in a Heatwave?
People using GLP-1 receptor agonists, including semaglutide, face a higher risk of dehydration and related illnesses. Common side effects like nausea, vomiting, and diarrhoea lead to significant fluid loss. These medications also slow gastric emptying, which can reduce overall food and fluid intake. Combined with increased sweating during hot weather, the risk of dehydration rises.
Dr Wylie explains: “If someone is already experiencing medication side effects that reduce fluid intake or increase fluid loss, they may be more vulnerable to dehydration-related illnesses such as heat exhaustion and heatstroke.”
Gallstones: Another Concern
Dehydration may further increase the risk of gallstones, which have been reported as a side effect of some weight loss medications. Dr Wylie says: “Dehydration can reduce bile flow and cause bile to become more concentrated within the gallbladder.”
Symptoms of Dehydration
According to the NHS, symptoms include:
- Thirst
- Headache and light-headedness
- Dark yellow, strong-smelling urine
- Less frequent urination
- Dizziness
- Fatigue
- Dry mouth, lips, and tongue
- Sunken eyes
Severe dehydration can cause confusion, muscle cramps, feeling faint, or weakness.
Prevention Tips
Do not rely solely on thirst as a cue to drink water. Drink regularly throughout the day. Adults should aim for six to eight glasses (1.5 to 2 litres) of water daily, with more needed during hot weather, illness, or activity.
- Keep a water bottle with you.
- Set reminders to drink water.
- Eat water-rich foods like watermelon, cucumbers, and oranges.
- Flavour water with sugar-free squash if needed.
- Limit sugary drinks, caffeine, and alcohol, which can dehydrate.
Seek medical advice if you experience persistent dizziness, severe fatigue, worsening nausea, or symptoms of dehydration.
Unexpected Hydration Help: Milk
Dr Natasha Dernando, medical director at Medichecks, suggests that milk can be more hydrating than water. The sugar, protein, and fat content slow stomach emptying, and sodium helps the body retain water. Soya milk also contains electrolytes for rehydration.
