GLP-1 Hair Loss: Does Wegovy or Zepbound Cause It, and Does It Grow Back?

Start with the primary sources, because the numbers are public and specific. The FDA-approved prescribing information for Wegovy (semaglutide injection, Novo Nordisk), as published on DailyMed with a June 2026 revision date, includes hair loss in its table of adverse reactions occurring in at least 2% of treated adults and more often than placebo. The row reads 1% for placebo and 3% for Wegovy. In the label's pooled analysis of three of the adult weight-management trials, hair loss was reported in 3.3% of patients on the standard Wegovy dose, broken down as 4% of women and 0.9% of men, against 1% on placebo. In the pediatric trial, 4% of adolescents on Wegovy reported hair loss and no placebo-treated patient did. For the higher-strength injection sold as Wegovy HD, the label reports hair loss in 5.8% of patients on that dose, 3.3% on the standard dose and 1.0% on placebo, with the difference again driven almost entirely by women.

The Zepbound (tirzepatide injection, Eli Lilly) prescribing information, DailyMed revision August 2026, does the same in its Table 1, which pools the two adult weight-reduction trials the label calls Study 1 and Study 2. Hair loss is listed at 1% for placebo and 5%, 4% and 5% for the three Zepbound maintenance doses, lowest to highest. A separate sentence in the label notes that hair loss was reported far more often in women than men in the pooled Zepbound groups, 7.1% versus 0.5%, and that the same sex gap appeared in the placebo groups, 1.3% versus 0%.

Both labels then add the sentence that matters most for understanding the mechanism, and they use nearly identical wording: hair loss adverse reactions in treated patients were associated with weight reduction. Neither manufacturer nor the FDA describes hair loss as a direct pharmacological effect of semaglutide or tirzepatide. The comparison that makes this concrete is the diabetes-indicated versions of the same molecules. The Ozempic label (semaglutide, revised May 2026) and the Mounjaro label (tirzepatide, revised August 2026) were built on type 2 diabetes trials with smaller weight changes, and neither lists hair loss in its clinical-trial adverse-reaction table. Both list alopecia only under Postmarketing Experience, the section for voluntary reports where the label itself notes that frequency and causality cannot be reliably established. Same drugs, different amount of weight lost, different table.

Two honest caveats. First, trial tables record what participants reported, and hair shedding may be under-reported in trials that were not designed to measure it. Second, a 3% or 5% rate does not mean 3% or 5% of people notice thinning; it means that share reported it as an adverse event. The broader picture of how these medications are tolerated is in our overview of GLP-1 side effects; this page stays on the one symptom.

Hair grows in cycles. A follicle spends years in its growth phase (anagen), a few weeks in transition, and then roughly three months in a resting phase (telogen) before the old hair sheds and a new one starts. At any moment around 10 to 15% of scalp hairs are resting, which is why a certain amount of daily shedding is normal.

Telogen effluvium is what dermatologists call it when a stressor pushes an unusually large share of follicles into the resting phase at once. The hairs do not fall out immediately. They sit in telogen, and then shed together about three months later. The 2015 review by Malkud in the Journal of Clinical and Diagnostic Research describes diffuse shedding of telogen hairs three to four months after the triggering event. The StatPearls telogen effluvium chapter, updated May 2024, puts the causative event approximately three months before shedding begins, with a range of one to six months, and lists crash dieting and low protein intake among the common triggers alongside childbirth, surgery, high fever and iron deficiency.

Rapid weight loss is on that trigger list independently of any medication, and the clearest recent data on it comes from a 2024 retrospective series in Annals of Dermatology by Kang and colleagues at a single dermatology center. Of 140 patients with telogen effluvium associated with weight loss, shedding began on average about one month after the weight loss started, following a mean loss of roughly 15% of body weight, and every patient improved during follow-up without any treatment, on average within about five months. Women in that series lost weight more slowly than men yet were more vulnerable to shedding, which is consistent with the sex split in both the Wegovy and Zepbound label tables. The study groups patients by cause (intentional dieting for just under half, surgery or an underlying illness for a minority, and unrecorded for the rest) but does not report whether any patient was using a GLP-1 or other weight-loss medication, so it speaks to weight loss as a trigger, not to any drug.

That is the shape of the current evidence. The labels record a modest excess of hair loss and attribute it to weight reduction; the dermatology literature describes a well-known, self-limiting shedding pattern triggered by rapid weight loss. The two fit together, but we found no published trial that has followed a GLP-1 cohort with scalp examinations to confirm that every case is telogen effluvium. Hair loss also has other causes that a prescriber will want to consider, including thyroid changes, iron status, hormonal shifts and hereditary patterned hair loss that a period of shedding can unmask. That is precisely why the timeline you record matters more than any general explanation.

Put the two timelines together and the delay explains most of the confusion people feel. Telogen effluvium runs on its own clock: follicles pushed into rest during a stretch of rapid loss shed one to three months later, the lag StatPearls and the Kang series describe. If that stretch happens in the first month or two of treatment, once the dose has been stepped up from the starting level, the lag puts the shedding somewhere between the second and the fifth month. That window is arithmetic from those sources, not a figure either label reports. Many people are on a steady, well-tolerated routine by then and are blindsided by hair in the shower drain that seems to come from nowhere.

The delay also runs in the other direction. Because shedding lags the trigger, the hair coming out in month four is a consequence of what happened in months one to three. Whatever changes you and your prescriber make now will not show in the shower for another two or three months, and regrowth is slower still: the StatPearls chapter notes that visible new growth can take up to six months to restart, while by definition acute telogen effluvium sheds for less than six months. A second titration step, another stretch of rapid loss, or a bout of illness can each restart the cycle, which is why some people describe a wave that recedes and then returns. This is also why hair loss can appear on the same timeline as a weight-loss plateau: the two are unrelated in mechanism, but the scale may have already slowed by the time the shedding peaks.

The practical consequence is that a month of shedding tells you almost nothing on its own. What tells you something is the sequence: when the rapid loss happened, when the shedding started, whether it is easing by the fourth or fifth month, and whether new short hairs are visible along the hairline. That is a record, and it is the only way to distinguish the temporary, expected pattern from something a prescriber needs to investigate.

The StatPearls list of telogen effluvium triggers includes low protein intake and iron deficiency, and the appetite suppression that makes semaglutide and tirzepatide work is exactly what makes under-eating protein easy. Hair is made of keratin, a protein, and the follicle is one of the fastest-dividing tissues in the body; when intake drops sharply, hair is among the first things the body deprioritizes. We found no published trial showing that a particular protein intake prevents GLP-1-associated shedding, and this page will not pretend otherwise. What the evidence supports is narrower and still useful: rapid loss and low protein are both recognized triggers, and protein is the one you can actually measure day to day.

The same reasoning already applies to muscle. The reason a protein-first plate is the standard advice on these medications is that weight lost with too little protein is more likely to include lean tissue; our guide to GLP-1 and muscle loss covers that in depth, and protein on a GLP-1 explains how to build meals around it when appetite is small. Hair is a second, more visible reason to take the same habit seriously. Individual protein targets depend on body weight, kidney function and activity, so the figure to aim for is one to set with your prescriber or a registered dietitian rather than one to lift from a website.

On supplements, the honest position is restraint. Biotin, collagen, zinc and iron are all sold for hair, and a prescriber may well decide to check iron, ferritin, thyroid or vitamin D because deficiencies are treatable causes of shedding that look identical to telogen effluvium. But taking those supplements without a measured deficiency has no demonstrated benefit for weight-loss shedding, the FDA's safety communication on biotin (issued in 2017 and updated in 2019) warns that biotin in supplements can interfere with some laboratory tests and produce incorrect results, and a prescriber will usually want to measure iron before recommending it. The useful question for your prescriber is whether any of these should be tested. The one thing that is safe to do today is to log what you eat, so that if your prescriber asks how much protein you have been managing, the answer is a number rather than a shrug.

Hair loss is worth mentioning at the next scheduled appointment even when it looks like the expected pattern, because it is a listed adverse reaction and your prescriber should know it happened. Some situations deserve a call sooner rather than later. Shedding that continues past five or six months without easing falls outside the acute telogen effluvium pattern described in the literature. Hair coming out in patches rather than diffusely across the whole scalp is a different picture and points away from telogen effluvium. So does scalp pain, itching, redness or scaling. Thinning that concentrates at the crown or temples with a widening parting, particularly if it runs in your family, may be a patterned hair loss that the shedding has unmasked. And hair loss alongside unusual fatigue, cold intolerance, or changes in your periods is a reason to ask about thyroid and iron testing. None of these are diagnoses; they are the cues a clinician uses to decide what to check.

What you should not do is change the medication on your own. Some people stop or stretch their doses in the hope of protecting their hair. Because shedding lags its trigger by months, that change would not show in the drain for a long time, it would undo the weight loss the medication was prescribed for, and it removes the prescriber's ability to judge the timeline. Whether a dose is held, adjusted or continued is their decision, informed by your record. The pharmacist is also a good first contact for the label details and for checking whether anything else you take has hair loss listed as a side effect.

What to bring is short. The date you first noticed increased shedding. Your weight readings over the three months before that date, since the rate of loss is the trigger. How many months you have been on the medication and when each dose step happened. Your average daily protein over the same stretch. Any photos. And your questions, written down, because they evaporate in the room. Our checklist of questions to ask at a GLP-1 follow-up has a structure you can borrow, and how to prepare a GLP-1 summary for your doctor shows how to condense weeks of logging into a page.

Hair loss is the side effect people are worst at dating. It is gradual, it is noticed rather than felt, and by the time it registers it has usually been going on for weeks. A record fixes that, and it needs only four things.

Photos, on a schedule. Once a month, photograph the same parting, the same hairline and the same crown, in the same room, under the same light, from the same distance. Consistency matters more than quality; a monthly picture taken the same way beats a dozen taken at random. Add one of the shower drain or your brush if that is where you notice it. GLP-1 Tracker stores progress photos beside the weight history, so the month-four photo sits next to the month-four weight, and both stay in the app, on your iPhone and in your private iCloud, rather than in a shared album.

Dates, with the dose. Log the date you first noticed heavier shedding as a side-effect note attached to that day, and keep logging a short line whenever it clearly changes, up or down. Because the app keeps notes in the same timeline as your logged doses, the gap between a titration step and the start of shedding is visible without arithmetic, and that gap is exactly what a prescriber will ask about.

Weight-loss rate. The scale reading on the day of shedding is irrelevant; the rate over the previous three months is the trigger. A trend line that shows the steep stretch and the date it flattened is the single most explanatory chart you can bring. Reading your GLP-1 weight trend covers how to look at it as a slope rather than a number.

Protein, daily. Meal photos scanned for calories, protein and fiber, with protein shown first, give you a rolling average of what you actually ate through the fast-loss months rather than what you meant to eat. If your prescriber or dietitian sets a target, the log shows how often you reached it. Tracking protein on a GLP-1 walks through the mechanics.

None of this treats hair loss. It does something quieter and more useful: it turns a frightening, foggy experience into a dated sequence that shows whether the pattern is the temporary one the literature describes or something that needs a closer look. The app is free on iPhone, keeps everything on the device, and gives no medical advice; the interpretation stays with the people qualified to give it.