• Some Wegovy and Ozempic users are reporting the weight loss drugs have led to hair loss.
• The side effect was reported in 3% of patients in an Ozempic clinical trial.
• Temporary hair loss can happen when the body undergoes intense physical or emotional stress. 

Semaglutide, a drug developed for diabetes that was approved for weight loss by the FDA in 2021, has dramatically risen in popularity over the last year. Alongside that popularity has come wide-ranging reports of side effects from users, including nausea, dry mouth, and constipation.

One less common but disturbing potential side effect of the drug, which is sold under the brand names Ozempic and Wegovy:  Hair loss. While hair loss isn't a listed side effect for Ozempic, it did show up in 3% of people in Wegovy clinical trials,according to NBC News. It also appeared in 1% of people taking a placebo. 

The side effect is also often discussed on social media, including TikTok and Reddit. One Ozempic subreddit user complained of shedding everytime they brush their hair; another said they noticed chunks of hair coming out in the shower.

While unsettling, the phenomenon is not surprising. A type of temporary hair loss known as telogen effluvium is a known side effect of rapid weight loss, according to the Cleveland Clinic. Telogen effluvium, which is also known as stress shedding, can be triggered by many factors, including illness, surgery, fever, and pregnancy, Susan Bard, MD, board-certified dermatologist at Vive Dermatology, previously told Insider.

When the body experiences intense emotional or physical stress — like weight loss — it halts non-essential functions  like hair growth to preserve nutrients, according to Bard. In the case of semaglutide, "we know that for normal hair growth, adequate caloric intake should take place. So when patients are placed on severe calorie-restrictive diets, this will impact their hair growth," Dr. Rocio Salas-Whelan, an endocrinologist at New York Endocrinology, said on TikTok.

The shedding usually occurs three to six months after the period of stress, Bard told Insider, because it takes time for the hair cycle to shift into a new phase. Hair supplements like Biotin may help, but telogen effluvium usually ends on its own after several months, she said.

Salas-Whelan also recommends semaglutide patients avoid severe calorie restriction, which can lead to nutrient deficiency, add enough protein into their diets, and get good sleep at night. 

"With telogen effluvium, you will not lose all your hair, you will not go bald, and it will grow back, so it's not a permanent situation," Dr. Susan Massick, a dermatologist at Ohio State University, told NBC News.