Woman who lost 6.5 stone on Mounjaro describes severe early fatigue and appetite loss

A woman who says she lost 6.5 stone in a year while using the diabetes medication Mounjaro described acute early side effects that left her extremely tired and without appetite, and urged others to allow time to adjust to the drug.

The TikToker, who posts as Insightful Lucy and identified herself as a Welsh mother, said she began on a 2.5 mg dose and experienced an "instant" loss of hunger within hours. She told followers that in the days after her first injections she became so fatigued that she would take her son to school and then "lie on the settee" and be "in and out of sleep all day," adding that the treatment "drained the life out of me." She also reported nausea and headache at the outset, but said those symptoms gradually subsided and her energy levels improved over weeks.

Lucy said she later increased to a 7.5 mg dose and again experienced unpleasant side effects on a couple of occasions, reporting episodes of so-called "sulphur burps" that she described as manageable. As a working parent she advised anyone planning to start the injections to allow a period of adjustment, telling a friend not to begin during school holidays because the early fatigue made day-to-day childcare more difficult.

The accounts come amid major changes to the drug's pricing and supply in the United Kingdom. Eli Lilly announced a planned wholesale price increase in August that would take effect Sept. 1, proposing a rise for the highest dose from £122 to £330 a month and a jump for mid-range strengths such as the 5 mg pen from roughly £92 to about £180. After pressure from private providers and pharmacists, commercial arrangements were struck that reduced the increase; under those deals the top dose is due to rise to £247.50, according to company statements.

Lilly said it is "working with private providers on commercial arrangements to maintain affordability and expect these to be passed onto patients" when the changes come into force. The company also announced a temporary pause to the supply of Mounjaro to the UK ahead of the price change, saying the move was to avoid stockpiling at the lower price.

The price announcement prompted widespread purchases by people using the drug privately, and pharmacies reported what they described as "Covid-style" panic-buying. Public-health experts and pharmacists warned that concern over costs could push some patients toward illegal or counterfeit supplies. Data obtained by the online pharmacy Chemist4U indicated that Border Force seized more than 18,000 illegal weight-loss and diabetes medicines, including fake Ozempic and Mounjaro pens, at Heathrow between June 2024 and June 2025.

Mounjaro (tirzepatide) and similar injectable therapies have seen rapid uptake for weight management. Estimates cited in reporting place use at about half a million NHS patients and roughly 15 million patients in the United States, with private use beyond those figures. Clinical guidance in the U.K. recommends prescription of such medications for people with a body mass index (BMI) over 35 with at least one weight-related comorbidity, or for people with a BMI of 30 to 34.9 who meet criteria for specialist weight-management referral.

Clinicians say side-effect profiles can vary by dose and patient, and advise that people starting injectable GLP-1 or dual GIP/GLP-1 receptor agonists be monitored and discuss timing and dosage with their prescriber. Users and prospective patients are encouraged to consult health professionals about potential side effects, appropriate dosing schedules and safe access to licensed products.