It’s been hailed as a ‘miracle’ fat-busting drug and a breakthrough in the war on obesity — but users of Mounjaro have revealed yet another unpleasant side effect.
Despite their undeniable slimming effects, injections of GLP-1 drugs, such as Ozempic and Wegovy, have been linked to a catalogue of side effects including muscle loss, hair loss and ‘Ozempic face’.
Now users of weight-loss jab tirzepatide, sold as Mounjaro and coined the ‘King Kong’ of slimming injections, are complaining the medicine is leaving them feeling permanently ‘freezing’ cold.
Scores of TikTok users have shared clips demonstrating their drug-induced chills, tagging the videos with the hashtag ‘jaro jitters’ and ‘Mounjaro side effects’.
One recent TikTok video posted by @katie.k1986, who has been taking the drug for just over a month, sees the social media user wrapped up in a fleece while telling followers she is ‘so cold I could be in Greenland’.
Several TikTok users commented on the video, echoing Katie’s experience.
‘I’m watching this video under an electric blanket,’ said one, while another willed the menopause to begin to increase her body temperature.
Another video posted by @life.withleanne, who has been injecting Mounjaro for almost six months, sees the social media suggest that Eskimos are warmer than her.
Social media user @nicinackinoo (pictured left) complained of the side-effect. She said: ‘I am wearing a granny nighty, a dressing gown, a throw and another throw and socks and I am still shivering.’ In a video posted by @life.withleanne (pictured right), it sees her confess there are ‘Eskimo’s warmer’ than her
Meanwhile user @nicinackinoo said: ‘I am wearing a granny nighty, a dressing gown, a throw and another throw and socks and I am still shivering.’
Now, Professor Alex Miras, leading obesity expert from Ulster University, has offered a simple explanation for the phenomenon.
He explained that when we lose weight, our energy expenditure reduces in an attempt to preserve fat — meaning we burn fewer calories.
But the process of burning energy generates heat, meaning we feel colder when are body does this less often.
Professor Miras told MailOnline: ‘When people reach their weight plateau, which is usually a year after starting the medication, they start burning more energy and are less likely to complain of feeling cold.’
Professor John Wilding, an expert in cardiovascular and metabolic medicine at the University of Liverpool, said feeling cold is simply the result of losing fat.
He told MailOnline: ‘People who lose weight will have less fat, and as this acts as an insulator, it might make sense that they feel the cold more; there is also a slight slowing of your energy expenditure.
‘Cold intolerance is known to occur with weight loss, whether this happens by dieting, medicines, or with weight loss surgery.
‘So, if people are experiencing this, it is likely due to the weight loss, rather than a specific effect of the medication used.’
Experts say the side effect of feeling cold while taking Mounjaro is simply the result of losing fat and therefore the body’s insulation
Like many drugs, the side effects of Mounjaro can be serious and more than a 100 deaths have been recorded since 2023
Clinical trials have reported a number of side effects from taking Mounjaro.
One, involving 900 participants, found a fifth suffered from nausea and diarrhoea, and about one in 10 reported vomiting or constipation.
US pharmaceutical giant Eli Lilly, who makes the drug, said Mounjaro’s side effects were most commonly reported when the dose was increased.
Only about 4 per cent and 7.5 per cent of participants, in the 10mg and 15mg dosing cohorts respectively, quit the study due to side effects.
Other people taking the drug outside of clinical trials have reported experiencing hair loss while taking Mounjaro.
EU drug watchdog, the European Medicines Agency (EMA), said earlier this year that research on rodents has suggested the artificial hormones packaged in tirzepatide could raise the risk of medullary thyroid cancer.
The EMA has ruled that a monitoring study of patients taking the drug is required to explore the potential of a raised cancer risk in humans.
Some users have also commented that GLP-1 drugs cause premature aging.
That’s because weight-loss injections don’t target fat specifically, instead, triggering weight loss by affecting appetite.
The result is that patients can also lose muscle mass by not eating as much protein, the building block of muscle, as before taking the drug.
Fat also drops off the face, not just the belly, making many people look gaunt, known as ‘Ozempic face’.
Since the fat in our face helps gives smooth plump cheeks and wrinkle free foreheads, rapidly losing it can make people rapidly look much older.
However, like many drugs, the side effects of Mounjaro can be serious.
Susan McGowan, a 58 year-old nurse from Lanarkshire, died from multiple organ failure, septic shock and pancreatitis after taking two low-dose injections of tirzepatide.
She took the jabs for a two-week period before her death on September 4. It is thought to be the first time the medicine has been listed as a contributing factor on a death certificate.
In another case, Meredith Hotchkiss, a nurse from Meridian, Idaho in the US, said she will now likely be tube fed for the rest of her life, after taking the injection for just a matter of weeks.
The 56-year-old who said the jab had ‘devastated’ her life is one hundreds of patients who have joined a a multi-state US lawsuit against the drugmakers of Mounjaro and another weight loss jab Ozempic.
Thousands more patients who also suffered extreme side-effects are expected to join the legal action as it progresses, lawyers say.
