Dara Smith, 34, has detailed her experience of losing approximately 50% of her hair after taking Mounjaro, a GLP-1 agonist medication, between January and December of last year. She reported noticing substantial hair shedding after increasing her dosage to 12mg, the second-highest strength available.
Smith described the hair loss as pervasive, with strands found on her clothing and bedding, and particularly noticeable during showering or brushing her hair. "I was really upset when I realized that Mounjaro was the cause of my hair loss, as I'd had such a positive journey with the jab until that point," she stated. She noted that she had not previously encountered widespread discussion about this potential side effect.
Studies indicate that patients using GLP-1 agonist injections, such as Mounjaro, face a 40-70% risk of hair loss. This phenomenon is thought to be triggered by a reduced intake of essential nutrients vital for hair growth, including protein, iron, and zinc. Hair shedding often becomes apparent a few months after starting the medication, which can make it seem disconnected from the drug's initial administration.
An estimated 1.6 million people in Britain are believed to use weight-loss injections like Mounjaro, Ozempic, and Wegovy, with most obtaining private prescriptions. Smith began her Mounjaro treatment in January 2025, weighing around 13 stone. She had previously struggled with consistent healthy eating and exercise routines.
After hearing about Mounjaro from colleagues, she obtained a 2.5mg dose online. She reported rapid weight loss, shedding 10 pounds in the first week, and noted that her appetite significantly decreased. Initially, she experienced few side effects, reporting only occasional headaches.
Smith gradually increased her dosage to 12mg. By August 2025, she had lost three stone and five pounds, reaching a weight of nine-and-a-half stone. It was around this time that she first observed thinning and subsequent shedding of her hair.
Suspecting a link to protein intake, she increased her daily protein consumption to 100g, well above the average 45g recommended for adult women. She also incorporated rosemary oil, pumpkin seed extract, collagen, and biotin into her regimen, but her hair loss persisted. "The damage was done, it was too late," she said. "Nothing I did helped."
Despite her concerns, Smith continued Mounjaro until December 2025, when she achieved her goal weight of eight-and-a-half stone. She then paused the medication in an attempt to address the hair loss. Upon discontinuing Mounjaro, her hair stopped shedding.
However, in late January of this year, she resumed the medication due to concerns about potential weight regain. Notably, she has not experienced any hair loss since restarting. She also claims to have recovered 20% of her lost hair, which she attributes to a strict hair care routine. This routine includes taking two hair growth supplements and a scoop of collagen powder daily, along with applying a rosemary and rice water spray to her scalp five times a week, and using a specialist shampoo designed to promote hair growth.
While some studies suggest rosemary oil may aid hair growth by stimulating follicles, the evidence is limited. Experts generally agree that collagen powders and hair growth supplements are unlikely to be effective unless a specific nutrient deficiency is present. Nevertheless, Smith believes these methods have contributed to her hair regrowth, stating, "There's now so much growth throughout my whole hair, but I still only have about 70 percent of the hair I had before I lost weight."
She advises others considering Mounjaro to "make sure to work out your nutrient requirements from day one." Despite the hair loss, Smith considers taking Mounjaro "one of the best decisions of my life," crediting it with significant improvements in her confidence and mindset.