Weight-Loss Jab Users Urged to Stay Hydrated as UK Temperatures Rise
Health expert warns popular injections could increase dehydration risk during warmer weather
As forecasters predict a spell of warmer weather across parts of the UK, with some areas expected to experience temperatures reaching the mid-to-high 20s, health experts are urging people using weight-loss injections to take extra care to stay hydrated.
Popular weight-loss medications containing GLP-1 receptor agonists, including semaglutide, have surged in popularity as more people turn to medical treatments to support weight management. However, experts are warning that rising temperatures could create an additional health concern for some users.
Dr Suzanne Wylie, GP and medical adviser for IQdoctor, says people taking weight-loss injections may face a higher risk of dehydration, particularly during warmer weather.
“Weight-loss injections containing GLP-1 receptor agonists, such as semaglutide, have transformed obesity treatment and weight management, but they can increase the risk of dehydration, especially during periods of warmer weather,” says Dr Wylie.
“This is largely because some of the most common side effects include nausea, vomiting and diarrhoea, all of which can lead to significant fluid loss. These medications also slow gastric emptying, helping people feel fuller for longer, but this can sometimes mean individuals unintentionally eat and drink less overall.”
The concern becomes more significant during periods of hotter weather, when the body naturally loses more fluids through sweating in order to regulate temperature.
“Hot weather creates an additional challenge because the body loses more fluid through sweating. These losses need to be replaced,” 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, in more serious cases, heatstroke.”
Symptoms of dehydration can range from headaches and fatigue to dizziness, dry mouth and darker urine. More severe dehydration may cause confusion, weakness, muscle cramps or feeling faint.
Dr Wylie says people should not rely solely on thirst as a cue to drink more fluids.
“Many people wait until they feel thirsty before drinking water, but thirst often occurs after the body has already started becoming dehydrated. Instead, it is important to drink regularly throughout the day, even if you don’t feel particularly thirsty.”
While hydration needs vary from person to person, adults should generally aim for around six to eight glasses of fluid per day, approximately 1.5–2 litres, with higher amounts often needed during hot weather, illness or increased activity.
She also recommends practical steps such as:
- Carrying a water bottle and sipping regularly throughout the day
- Setting reminders to drink fluids
- Eating water-rich foods such as watermelon, cucumber and oranges
- Flavouring water with sugar-free squash if plain water becomes unappealing
- Limiting excessive sugary drinks and alcohol
Dr Wylie also highlights another lesser-known concern associated with dehydration.
“Gallstones are a recognised but relatively uncommon side effect associated with rapid weight loss and some weight-loss medications. Dehydration may further increase this risk because it can reduce bile flow and cause bile to become more concentrated within the gallbladder.”
She adds that anyone experiencing persistent dizziness, severe fatigue, worsening nausea or symptoms of dehydration should seek medical advice.
With temperatures expected to rise across parts of the UK over the coming days, experts say staying hydrated may be one of the simplest but most important ways for people using weight-loss medications to protect their health.
