A recent study has found that women using Mounjaro for weight loss are nearly twice as likely to experience hair loss compared to those using Wegovy or Ozempic.
Weight loss injections have become a popular tool for managing obesity, but new research suggests they may come with an unexpected side effect: hair loss. A study conducted by Australian scientists has found that women using Mounjaro are nearly twice as likely to experience new-onset alopecia compared to those using Wegovy or Ozempic.
The study, which compared 11,046 patients taking Mounjaro with the same number taking semaglutide, found that roughly four percent of Mounjaro users developed hair loss, compared to just under three percent of those using other GLP-1s and diabetes medication.
The risk was even higher among women, with around six percent of female Mounjaro injectors suffering the side effect, compared to three percent on other jabs.
Understanding the Link Between Weight Loss and Hair Loss
The study’s lead author, Venky Soundararajan suggested that the effect is likely due to rapid weight loss and its associated nutritional deficiencies rather than the jabs themselves.
Weight loss jab-associated hair loss is typically a form of non-scarring alopecia, meaning the hair follicles remain intact and hair can grow back.
The researchers also found that the risk of hair loss was higher among Mounjaro users regardless of how much weight patients lost or the dose they received. However, they noted that the findings may partly reflect the fact that women are more likely to seek medical help for hair loss, which can carry a significant social stigma.
Hormonal and Metabolic Factors
The study also found that alopecia was more common in patients with thyroid disease and other hormonal-related conditions, suggesting that underlying hormonal or metabolic factors may contribute to the risk. The team suggested that the changes in drug absorption caused by the weight loss jabs could influence hair growth, particularly in individuals with underlying hormonal conditions.
The findings should help inform discussions between doctors and patients, particularly women and those with a history of hair loss, autoimmune disease, or nutrient deficiencies. However, Soundararajan cautioned that clinically meaningful weight loss should not be equated with inevitable hair loss.
Regulatory Response and Future Research
In 2026 alone, the UK Medicines and Healthcare Products Regulatory Agency (MHRA) has received nearly 400 reports of hair loss relating to tirzepatide, the generic name for Mounjaro. The watchdog has also received 148 reports of hair loss linked to semaglutide.
The US Food and Drug Administration (FDA) is currently evaluating the effect Wegovy, Ozempic, and Mounjaro have on hair loss. Researchers from the University of Pennsylvania believe the most likely mechanism is that people are not getting enough nutrients to support healthy hair growth. Severe calorie restriction and rapid weight loss can contribute to physiological stress and micronutrient deficiencies, which can disrupt the hair growth cycle.
Experts who were not involved in the study say the absolute risk remains low. However, the findings highlight the importance of individualized counseling and surveillance for patients using weight loss jabs.
