A woman who has lost 6.5 stone in a year using Mounjaro has shared the first side effects she had – including debilitating tiredness that left her ‘in and out of sleep’ in the daytime.
The TikToker, who goes by the name Insightful Lucy on the social media platform, offered advice based on her own experience with weight-loss jabs, explaining what symptoms she initially had.
The Welsh mum weighed in at 16 stone 11lbs before the treatment and now tips the scales at just over 9 stone.
She told her followers: ‘I get this question a lot about what the side effects were when I took my first ever dose.’
The first, she explained, was an immediate loss of appetite, after taking the lowest dose of 2.5mg, saying: ‘Instantly the food noise went within a couple of hours – I just wasn’t hungry at all, it was crazy.’
However, the next side effect wasn’t quite so welcome, she said in the clip, which was just over a minute long
Lucy said she became so fatigued that if she wasn’t working, she would take her son to school and then ‘lie on the settee’ and be ‘in and out of sleep all day’.
She admitted the drug, which is made by Eli Lilly and has risen in price since Sept 1st, ‘drained the life out of me’.
TikToker Insightful Lucy has lost 6.5 stone in a year using ‘King Kong’ weight-loss drug Mounjaro. In a recent video, she revealed the side effects that had hit her straight away when she first began on a 2.5mg dose
Other minor symptoms she experienced included nausea and a headache but she explained that all her symptoms gradually subsided as the weeks went on, with her energy levels rising.
Rising to the 7.5mg dose, Lucy said once again she experienced unpleasant side effects, although only a couple of times.
She explained she had ‘sulphur burps’ twice but says they were manageable.
As a busy parent, she said ensuring you take time to adapt to taking the drug was important, saying she advised a friend who planned to start on weight loss jabs in the summer holidays not to do it.
She told her: ‘wait til they’re back in school’, adding: ‘you’re so drained, you just need that time to yourself’.
Eli Lilly announced in August that wholesale prices would more than double from September 1 – with the highest dose rising from £122 to £330 a month.
Mid-range doses, such as the 5mg pen, were also set to jump from about £92 to £180.
But it has now been made public that pharmacists and private providers have struck commercial deals with Lilly to keep prices lower.
The Welsh mum pictured before she began taking Mounjaro, when she weighed in at 16 stone 11lbs
Eli Lilly, the pharmaceutical company behind the drug, has backed down to mounting pressure over the planned price hike, and the increased cost for the fat jab will now not be as high as previously announced
Under these arrangements, the top dose will rise to £247.50—almost £100 less than the new list price—with smaller discounts applied to lower strengths.
In a statement, Lilly said: ‘We are working with private providers on commercial arrangements to maintain affordability and expect these to be passed onto patients when the change is effective on 1 September.
‘We are already seeing providers respond in different ways to the list price change, with a range of options available for eligible patients.’
The move comes as slimmers have rushed to stockpile months worth of Mounjaro after panic grew over its soaring cost.
Social media users have boasted online of getting their hands on months worth of injection pens, to avoid having to pay the new price.
Pharmacies have also warned that patients have been ‘Covid-style’ panic-buying the drug since the announcement.
It has left some experts fearing patients may be tempted by black market sellers who flog the jabs at reduced prices—putting their health at risk.
More than 18,000 illegal weight-loss and diabetes medications, including fake Ozempic and Mounjaro pens, were seized by Border Force at Heathrow between June 2024 and June 2025.
The data, obtained by the online pharmacy group Chemist4U, showed that smugglers had been stopped at the airport with fake Mounjaro pens hidden on their bodies.
Yesterday, Lilly also announced it was temporarily pausing the supply of Mounjaro to the UK until the price hike is enforced.
The US pharmaceutical giant claimed this was to ensure they are not stockpiling at the current lower price.
At least half a million NHS patients and some 15million patients in the US are now thought to be using weight-loss jabs, which can help patients lose up to 20 per cent of their body weight in just a few months.
And the numbers using them privately are even higher.
Under official guidelines, only patients who have a body mass index (BMI) of over 35 and at least one weight-related health problem like high blood pressure, or those who have a BMI of 30 to 34.9 and meet the criteria for referral to a specialist weight management service, should be prescribed weight-loss jabs.
