Nour Mansour was over the moon when she started taking the weight-loss injection Mounjaro.
In less than seven months, she dropped from a size 18 to a size 8, gaining a huge boost in confidence after struggling with her weight since having her twin daughters.
But about six months into treatment, she noticed something alarming—her hair began falling out in clumps.
“I’d run my hands through my hair and it would just come out,” says Nour, an administration assistant from London.
“Being Middle Eastern, my hair was everything to me. It used to be thick and glossy, reaching almost to my hips.
Suddenly, it became dry and frizzy, and my temples were thinning so badly I started wearing caps all the time. It was heartbreaking.”
Many Mounjaro Users Report Similar Hair Loss Experiences
Nour’s story isn’t unique. Across social media, countless users of Mounjaro have shared similar hair loss concerns—some even stopping their injections because of it.
Last month, former MP Nadine Dorries opened up about her own shock at losing hair after starting the drug, revealing she hadn’t come across this side effect in her research and kept it to herself out of embarrassment.
Clinical trials have shown that hair loss is a reported side effect in over five percent of users on GLP-1 weight-loss medications like Mounjaro.
But experts say the drug itself probably isn’t directly to blame.
Experts Explain Why Rapid Weight Loss Can Trigger Hair Loss
Dr. David Fenton, a top dermatologist and hair loss specialist, explains, “When people lose weight quickly or drastically change their diet, they often don’t get enough nutrients essential for healthy hair growth—like iron, vitamin B12, folate, zinc, and vitamin D.”
He adds that protein intake matters too, since hair is mostly made of keratin, a protein. Without enough, hair becomes fragile and breaks easily.
Other symptoms like brittle nails or slower nail growth have also been linked to nutrient shortages seen in GLP-1 users.
Diabetes expert Dr. David Strain points out that while clinical trial participants get monitored diets, real-world users often don’t know how to balance their nutrition or when to take supplements.
What You Can Do If You Notice Hair Loss on Mounjaro
If you’re worried about shedding, Dr. Fenton suggests getting a blood test to check nutrient levels—especially if you’re vegan or vegetarian.
Iron is found in red meat, seafood, leafy greens, and nuts, while zinc comes from dairy, eggs, and whole grains.
Vitamin B12, mostly in animal products, can be taken as a supplement.
Hair growth normally cycles through phases, with about 90% of follicles actively growing and 10% resting.
But when the body is stressed by illness or rapid weight loss, more follicles enter the shedding phase, a condition called telogen effluvium.
This causes noticeable thinning and shedding, especially during brushing or washing.
This kind of hair loss is similar to what many women experience postpartum and usually improves over time.
But nutrient deficiencies or being underweight can slow the recovery.
Real-Life Stories Show How Nutrition and Patience Can Help
Grace Parkin, a 34-year-old mum from Sheffield, lost seven stone in a year on Mounjaro but started noticing hair thinning within three months.
“At first, I wasn’t eating enough because I just didn’t feel hungry,” she admits.
“Once I focused on a balanced diet, my hair started to grow back.”
Nour had a similar turnaround after consulting her GP. She began taking supplements and eating better, and the shedding stopped.
Dr. Fenton reassures that for most people, hair will grow back with the right care.
But if hair loss continues despite eating well, it’s important to check in with a doctor.