Nour Mansour, a 28-year-old mother of twin daughters, experienced a significant transformation after losing over three stone in less than seven months with the aid of Mounjaro. While initially thrilled by the weight loss and the resulting boost in confidence, a disturbing side effect emerged after six months: severe hair shedding. Nour recounted that her once full, hip-length hair began to fall out in clumps, transitioning from "glossy and thick to dry and frizzy," with noticeable thinning at her temples, prompting her to constantly wear caps and headbands.

Many women using medications like Mounjaro have reported similar issues of hair thinning or shedding, particularly alongside rapid weight loss or hormonal shifts. However, medical experts clarify that the medication itself is not typically the cause. Dr. David Fenton, a consultant dermatologist and hair loss specialist, explained that rapid weight loss or sudden dietary changes can lead to deficiencies in essential nutrients for healthy hair growth, such as iron, vitamin B12, folate, zinc, vitamin D, and protein. Hair is primarily composed of keratin, a protein, and insufficient protein intake can make tresses weak and brittle. Other side effects observed in GLP-1 users, like brittle fingernails and slowed nail growth, have also been linked to these nutritional deficiencies.

Dr. David Strain, a diabetes expert, pointed out that while participants in clinical trials are closely monitored and maintained on nutrient-rich diets, real-world users often lack awareness about meeting their nutritional needs or the appropriate supplements. Dr. Fenton advises that anyone concerned about hair loss should consider a blood test, especially if they follow a vegan or vegetarian diet. To boost iron intake, recommended foods include red meat, dark leafy greens (like kale and spinach), nuts, and seafood. Dairy products such as yogurt and kefir, eggs, and wholegrains are good sources of zinc. Vitamin B12, predominantly found in animal products, is also widely available in supplement form.

Dr. Fenton further elaborated on the hair growth cycle, noting that normally, about 90 percent of hair follicles are in the growing phase, with 10 percent resting. However, under stress—whether from illness or significant weight loss—this cycle can alter, causing a higher percentage of follicles to enter the shedding phase. He emphasized that "The more weight you lose, and the faster you lose it, the higher the risk." This condition, known as telogen effluvium, is similar to postpartum hair loss and typically resolves over time. Fortunately, steps can be taken to minimize damage, including slowing the rate of weight loss to reduce bodily stress. Nour herself found relief after consulting her GP, beginning a supplement regimen, and prioritizing a healthy diet, which successfully halted the shedding.