Why Does Zepbound (Tirzepatide) Cause Hair Loss? The Biology Explained

What the Zepbound label actually reports

The Zepbound label lists hair loss among adverse reactions reported in at least 2% of patients and more often than with placebo [1]. In the pooled weight-management trials, 958 patients received placebo, 630 received 5 mg, 948 received 10 mg and 941 received 15 mg; treatment lasted up to 72 weeks [1]. Hair loss was reported by 5% of patients on 5 mg, 4% on 10 mg and 5% on 15 mg, compared with 1% on placebo [1].

The label states that hair loss was associated with weight reduction and was more frequent in women: 7.1% of women versus 0.5% of men taking Zepbound, and 1.3% of women versus 0% of men on placebo [1]. No Zepbound-treated patient stopped treatment because of hair loss; one placebo-treated patient did [1].

Weight reduction is the explanation the label gives

The only context the label gives for the hair loss is its association with weight reduction [1]. A 2026 systematic review points the same way. It screened 133 studies and included 24; among GLP-1 receptor agonists, semaglutide and tirzepatide had the highest reported incidence of hair loss and the most frequent signals in pharmacovigilance databases, with telogen effluvium and androgenetic alopecia the predominant subtypes reported [2]. Tirzepatide, the agent associated with the greatest weight loss in that review, was most often linked to telogen effluvium, and rapid weight loss emerged as a potential contributor; the authors state that causality has not been established and call for prospective randomized trials [2].

The weight change on tirzepatide is large. In SURMOUNT-1 (2,539 adults, 72 weeks), mean weight change was -15.0% on 5 mg, -19.5% on 10 mg and -20.9% on 15 mg, versus -3.1% on placebo [3].

The hair cycle behind the shedding

Scalp follicles cycle through growth (anagen), a short transition (catagen) and rest (telogen) phases. Telogen effluvium is diffuse shedding in which an unusually large share of follicles are in the resting phase at the same time; it was the subtype most often linked to tirzepatide in the review above [2].

A cross-sectional survey of 254 people using GLP-1 receptor agonists for weight loss (Mounjaro, Ozempic, Saxenda or Victoza) found no significant difference in hair-loss prevalence between the products (p=0.116), but severe hair loss was reported more often by Mounjaro users (43.4%) and Saxenda users (42.9%) than by users of the other injections (p<0.001) [4]. The authors describe this hair loss as typically non-scarring and reversible [4].

Does tirzepatide act on the follicle directly?

The label ties the reported hair loss to weight reduction and describes no effect of tirzepatide on hair follicles [1]. The 2026 systematic review treats rapid weight loss as a potential contributor and leaves the causal question open [2].

Who reports it, and how strong the signals are

The sex difference in the label is large: 7.1% of women versus 0.5% of men on Zepbound [1]. The systematic review likewise found women disproportionately affected [2], and the 254-person survey found men less likely to report hair loss than women (adjusted odds ratio 0.36, p=0.003), with Mounjaro users having higher odds than users of the other injections (adjusted odds ratio 3.02, p=0.009); duration of use was not a significant predictor [4].

Post-marketing analyses have produced differing alopecia-reporting signals for tirzepatide and semaglutide; these reports cannot establish which drug has a higher risk [5][6]. In one analysis of FDA Adverse Event Reporting System data from Q2 2022 through Q2 2025 (1,276 alopecia-related cases), semaglutide showed a significant positive reporting association with alopecia (adjusted reporting odds ratio 1.23, 95% CI 1.11 to 1.35), while tirzepatide showed lower or non-significant disproportionality signals [5]. A separate disproportionality analysis of 215,337 deduplicated reports found alopecia relatively more frequently reported with tirzepatide (reporting odds ratio 0.74) and concluded that its findings reflect spontaneous reporting rather than comparative clinical risk or causality [6]. A retrospective analysis of the same database found alopecia among the five most common skin reactions across GLP-1 agonists, with significantly higher alopecia reporting when the drugs were used for type 2 diabetes than for weight management [7].

Iron and biotin: what the general hair-loss reviews say

These reviews concern hair loss in general, not Zepbound. A review of iron deficiency and hair loss concluded that there is insufficient evidence to recommend universal screening for iron deficiency in people with hair loss, and insufficient evidence to recommend iron supplementation in people with hair loss who have iron deficiency without anemia [8]. A review of biotin found 18 reported cases of biotin use for hair and nail changes, all in people with an underlying cause for poor growth, and concluded there is a lack of sufficient evidence for supplementation in healthy individuals [9].