Zepbound® and hair loss

Three documents, one set of trials

Zepbound® is tirzepatide, approved in the US alongside diet and activity to reduce and keep off excess weight in adults with obesity, or with overweight plus a weight-related condition, and, in adults with obesity, for moderate to severe obstructive sleep apnea. ^[1] Its side-effect table pools Study 1 (SURMOUNT-1, adults without diabetes) and Study 2 (SURMOUNT-2, adults with type 2 diabetes), each lasting 72 weeks, and lists reactions seen in at least 2% of people on Zepbound® and more often than on placebo. ^[1]

The Canadian monograph prints the same pool with patient counts, uses a 1% threshold and notes that the 5 mg arm existed only in SURMOUNT-1. ^[3] There is no Zepbound® document in the EU: tirzepatide is authorised there as Mounjaro®, and that product information also covers weight management. ^[4]

Why the weight indication matters

Hair loss shows up most clearly in trials of weight reduction. The European document says as much in a footnote: hair loss is a reaction that mainly applies to patients with overweight or obesity, with or without type 2 diabetes. ^[4] How the same molecule looks in diabetes-only labelling is covered on our Mounjaro® page.

Who was enrolled also shapes the headline. The Zepbound® safety pool was 37% male, and Study 1 was 68% female, so a pooled 4% to 5% sits far nearer the women’s 7.1% than the men’s 0.5%. ^[1] The two sleep apnea trials, Studies 5 and 6, enrolled mostly men (67% and 72%); the label gives no hair loss figure for them and says their reactions resembled those in the weight trials. ^[1]

For scale, average weight change after 72 weeks in Study 1 was −15.0%, −19.5% and −20.9% on 5, 10 and 15 mg against −3.1% on placebo, and in Study 2 it was −12.8% and −14.7% against −3.2%. ^[1] The label does not tie hair loss to any particular amount or pace of loss, and these are group averages rather than individual results.

What research on shedding adds

A 2026 systematic review and meta-analysis pooled nine interventional studies, seven of them randomised, with 4,114 people on GLP-1 receptor agonists. Hair loss was more likely than on placebo (risk ratio 3.252), the signal held in trials limited to overweight or obesity (risk ratio 3.587), and the event rate on treatment was 3.9%. ^[5] The abstract treats the drug class together, so it confirms the pattern rather than adding a Zepbound®-specific number.

A single-centre retrospective study from Korea described 140 people diagnosed with telogen effluvium after losing weight. On average they had lost 15.21% of their body weight at about 3.54 kg a month; the reason for the weight loss made no significant difference, and women and older adults appeared more vulnerable even when their loss was not larger. ^[6] There was no comparison group and no tirzepatide, but the average loss is comparable to the trial averages above.

Nutrition is the other open question. A post hoc analysis of SURMOUNT-1 to -4 (4,726 participants) found adverse events suggesting macronutrient malnutrition rare: abnormal weight loss in 0.03%, underweight in 0.06% and low albumin in 0.03% on tirzepatide. Vitamin-deficiency events were similar on tirzepatide and placebo (0.99% and 1.07%), and 0.38% versus 0.06% fell below a BMI of 18.5. Vitamin and mineral levels were not collected routinely, which limits the conclusions. ^[8]

Canada carries a warning the US label does not: malnutrition, sometimes severe, has been reported in people using Zepbound®, with risks that include vitamin, mineral and protein deficiency and low body weight, and clinicians are asked to consider nutritional guidance. ^[1][3]

Three layers of explanation

• Supported by the label: hair loss on Zepbound® was associated with weight reduction, and tirzepatide decreases calorie intake, likely through appetite. ^[1] The EU footnote points to the same group of people. ^[4]
• Proposed but not measured: shedding after weight loss fits telogen effluvium, which reviews describe as diffuse, non-scarring hair loss often set off by sudden weight loss. ^[6][7] The Zepbound® trials did not examine the hair itself, and how physical stress alters the hair cycle remains unknown. ^[7]
• General medical background: Cleveland Clinic explains that a stressor can push up to 70% of growing hairs into the resting stage early; shedding then tends to appear two to three months later, and a person may lose up to 300 strands a day rather than up to 100. ^[9]

Telling shedding apart from other hair loss

Cleveland Clinic describes telogen effluvium as heavy, quick shedding, usually most noticeable on top, with a scalp that looks healthy and no rash, itching, burning, pain or flaking. Male- and female-pattern loss, by contrast, thins slowly and is permanent without treatment. ^[9] A clinician can often confirm shedding by gently pulling a small bunch of hairs and asking about stresses about three months earlier. ^[9]

MedlinePlus lists other causes worth ruling out: inherited thinning, which affects many more men than women; childbirth, high fever, surgery or a major illness; crash diets short of protein; thyroid disease, anaemia, hormone changes and lupus; ringworm or bacterial infection of the scalp; tight hairstyles and heavy shampooing or blow-drying; and medicines such as ibuprofen and other NSAIDs, beta-blockers or calcium channel blockers, retinoids, birth control pills and certain antidepressants. ^[10] It also notes that some women aged 30 to 60 develop diffuse thinning with no known cause. ^[10]

Care steps in the sources

The Zepbound® Medication Guide gives no hair-specific advice; it asks only that side effects which trouble you or linger be raised with your healthcare provider. ^[2] Canada’s patient information adds that your healthcare professional may give nutrition guidance or suggest vitamins or supplements while you use Zepbound®. ^[3] General sources describe the following for shedding of this kind.

• Cleveland Clinic says most cases settle without treatment within six to eight months once the trigger is addressed, and new growth follows the shedding phase. ^[9]
• It advises against extreme or restrictive diets and suggests managing stress and getting enough sleep. ^[9]
• Ask your provider before starting supplements; MedlinePlus says one is likely to be recommended if a specific vitamin deficiency is found. ^[9][10]
• Cleveland Clinic names minoxidil, an over-the-counter scalp solution, among treatment options and says it should not be used in pregnancy or while breastfeeding; ask a pharmacist or your clinician whether it suits you. ^[9]
• A change of style, a hat, a wig or a hairpiece can cover thinning while hair regrows; MedlinePlus warns against having hairpieces sewn to the scalp. ^[10]

Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.