Why some people lose their hair when they’re on GLP-1s

By Asuka Koda, CNN

(CNN) — Carol Saffran started taking Ozempic a year ago to regulate her blood sugar after other medications were ineffective. She was prediabetic, a condition in which blood sugar levels are higher than normal, and her doctor prescribed Ozempic to help her avoid developing diabetes. She’s now close to her ideal body weight and has an appointment soon to check her progress in lowering her blood sugar – but after moving up to the highest dose of Ozempic, she started noticing something else.

“I would brush my hair and look at my hairbrush, and there was just a little bit more [hair] than normal,” said Saffran, 71, of the greater Boston area. “It’s not coming out in clumps or anything like that, but it’s definitely not as dense as it used to be. It just feels thinner. My hair is not as full as it used to be.”

A hair loss specialist at Tufts Medical Center, Dr. Farah Moustafa, director of laser and cosmetics, diagnosed Saffran with telogen effluvium: hair loss due to stress on the body. In Saffran’s case, that stress was the significant weight loss she experienced since being on Ozempic, Moustafa said.

The medicines have surged in popularity in recent years. A poll released Friday by KFF found that about 1 in 8 adults say they are currently taking a GLP-1 drug to treat a chronic disease, for weight loss or both — an increase of 6% since May 2024.

Still, side effects remain a key reason why some people decide to stop taking them. Hair loss is less common than well-known side effects such as nausea, vomiting or constipation, but it’s often discussed in online weight loss groups and among friends.

What is telogen effluvium?

There are four phases of hair growth. The first is the anagen or growth phase. It’s followed by the catagen or transitional phase, the telogen or resting phase and then the exogen or shedding phase. Normally, anagen is the longest phase.

Telogen effluvium is a condition that pushes an abnormal amount of hair follicles into the telogen phase, leading to more shedding than usual.

Dr. Anthony Rossi, a dermatologist at Memorial Sloan Kettering Cancer Center, said telogen effluvium often appears after a period of stress, such as childbirth, anesthesia or crash dieting.

“Any time people lose a significant amount of weight, typically in a short period of time, it is well-known that that can trigger an event called telogen effluvium, which basically is an alteration of the hair cycle in which an abnormal percentage of hair follicles enter into the shedding phase,” said Dr. Aron Nusbaum, a dermatologist and hair restoration surgeon at the Miami Hair Institute.

Telogen effluvium can happen three to six months after “an enticing event,” he said, “whether it be a physical or emotional stress, hormonal imbalance, a massive weight loss, a new medication, things like that.”

When the body is stressed, he said, large numbers of hair follicles in the anagen, or growth, phase prematurely enter the telogen, or resting, phase.

“It has to shift priority from nonessential things to more essential things. So hair is a nonessential appendage,” Rossi said.

Profound weight loss, rather than medication itself, appears to be the major mechanism for hair loss in people who have this particular GLP-1 side effect, said Nusbaum.

Malnutrition may play a role

Dr. Brian Wojeck, an obesity medicine specialist at the Yale School of Medicine, likened it to what happens after bariatric surgery, in which patients often experience temporary shedding due to stress and rapid metabolic change.

Wojeck suspects that sudden shifts in nutrition or vitamin levels may also contribute. Some people consider taking multivitamins while on GLP-1 medications to mitigate the effect, he said, although “there isn’t great data saying that taking a multivitamin is going to prevent hair loss.”

Rossi says some patients “are in a chronic malnourished state” while taking GLP-1s because the medication suppresses appetite.

“If you’re not getting enough of these micronutrients, your body is not going to be prioritizing anagen hair growth,” he said. “So it’s a mix of metabolic stress and then this relative caloric protein deficiency that happens.”

Rossi said the problem is becoming more common as the medications are increasingly used by people seeking cosmetic weight loss and who may not be getting adequate nutrition.

“The kicker in all this is that they’re being used so willy-nilly, in med spas, in direct-to-consumer compounding pharmacies. People are using them inappropriately,” he said.

“Many people we see using [the medication] are not obese, and they’re just using it for weight maintenance or weight optimization. People are starting at doses that they probably should not be starting at,” he said. “It’s causing them to not only not eat, but they’re getting less absorption of iron, zinc, vitamin D, B, B-12, all these essential amino acids that are in foods that you normally would be taking in.”

As a result, people often fail to meet the nutrient levels needed for hair growth. Each person needs 1 gram of protein per kilogram of body weight daily for keratin renewal and adequate ferritin, zinc, and vitamins B, D and B-12 for healthy hair, Rossi says.

He warned that GLP-1 medications can also have more serious effects, and patients should not use them lightly. “These are real medications that have real side effects. Hair loss, while it’s more cosmetic, can be devastating. But things like pancreatitis, nausea, vomiting, those are real.”

Other theories

There may also be other contributing factors to people’s hair loss, says Spencer Kobren, founder of the American Hair Loss Association.

Although “much of the hair loss being reported after starting GLP-1 medications could be temporary telogen effluvium related to rapid weight loss or nutritional stress,” he believes “it is entirely plausible that in those genetically predisposed to androgenetic alopecia, [GLP-1s] may be triggering its early onset.”

Nusbaum, of the Miami Hair Institute, said he has started to “see several patients with underlying androgenetic alopecia, which is male- or female-pattern hair loss, where that underlying condition is being exacerbated by the use of these medications.”

Androgenetic alopecia has a distinct pattern. For women, it mainly affects the frontal hairline, where hair meets the forehead. In men, it mainly affects the bitemporal and vertex areas: the sides of the scalp near the temples and the crown of the head, respectively. In contrast, telogen effluvium appears like diffuse hair shedding and thinning across all areas of the scalp.

Nusbaum points to a study in the Journal of the American Academy of Dermatology that examined a possible association between androgenetic alopecia and GLP-1 use, although the findings were inconclusive.

“In the literature, I don’t think that there is a strong association as of yet, but clinically we are definitely seeing a lot of patients in practice either with telogen effluvium or androgenetic alopecia, which we do believe is somehow being caused by the use of these medications,” Nusbaum said.

Other experts are skeptical of this explanation.

“From what I can tell, the best described mechanism for hair loss related to these novel weight loss agents is a telogen effluvium mechanism. Other mechanisms are under investigation, however, remain speculative at this time,” Wojeck said.

Rossi added, “Androgenetic alopecia is a pattern. We call it a patterned hair loss. It’s a gradual one.”

A Novo Nordisk spokesperson told CNN that hair loss is an identified risk with semaglutide and is listed as a side effect.

“For example, in clinical trials of Wegovy, hair loss was reported in 2.5% of Wegovy-treated adult patients vs 1.0% of placebo-treated adult patients. Hair loss was reported more frequently in patients with a greater weight loss (≥20%) suggesting that the events of hair loss were potentially related to the magnitude of weight loss. Alopecia is also included in the post-marketing experience sections of the Prescribing Information for Ozempic and Rybelsus,” the spokesperson said.

A spokesperson from Eli Lilly also said that “hair loss has been observed with weight loss interventions” and that the side effect is listed on Zepbound labels but not Mounjaro, as it is “an adjunct to diet and exercise to help improve glycemic control in adults with type 2 diabetes; it is not approved for weight loss.”

“It is addressed in the Zepbound label because it is may be an adverse reaction potentially related to weight reduction,” the spokesperson said. The label notes, “In Zepbound clinical trials, hair loss was reported more frequently in female than male patients in the Zepbound (7.1% female versus 0.5% male) and placebo (1.3% female versus 0% male) treatment groups.”

Treatments for hair loss

Experts say telogen effluvium with GLP-1 use is typically temporary, but people who develop hair loss should seek medical evaluation. Some can go into a chronic telogen effluvium state, in which shedding continues for more than six months, Rossi says.

Since telogen effluvium’s hair loss occurs with stress on the body, Moustafa explained, once that stressor is removed, patients should make a full recovery.

“Oral minoxidil is a really great medication that is given via a prescription. There are several ways we can intervene pharmacologically on behalf of our patients to try and get them [to recover their hair] faster,” she said, such as the hair-loss medication minoxidil.

This is common for patients who need to stay on a medication that is causing telogen effluvium, such as those who may need to keep using the highest dose of Ozempic, Moustafa said. Saffran, who wants to stay on Ozempic because of its other benefits, will be lowering her dosage as well as starting minoxidil.

However, Nusbaum points out that “without having the correct diagnosis, you won’t receive the proper treatment.”

That starts with ruling out any underlying causes.

“We look at several lab values, look for vitamin and mineral deficiencies, look for hormonal imbalances, and typically, if it’s telogen effluvium, correcting the underlying cause will lead to a more rapid resolution of the hair shedding and eventual regrowth,” he said. “There are some treatments that can help speed up the cessation of shedding and push the hair cycle back into the regrowth. In androgenetic alopecia, we’re looking at more long-term therapies.”

For Saffran, Moustafa first ruled out other causes as well.

“When I did her exam, she has an amazing hair density at baseline, so she started out with really thick, beautiful hair,” Moustafa said, and there was not any evidence of female-pattern hair loss related to age. “So I think it really is a pure telogen effluvium that she’s experiencing.”

Moustafa advises people using GLP-1s who are concerned about hair loss to “keep an eye on the rate of your hair shedding and the degree of your weight loss,” as well as “being your own advocate in many ways, discussing these things with your prescribing doctor and asking for the referral so that you can get the support to mitigate it.”

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