The answer so far
In plain English: shedding has many possible causes. A report in a trial is a reason to investigate, not proof that a medicine caused every case or that a supplement will fix it.
Hair loss was reported more often with some weight-loss medicines than with placebo in clinical trials. In pooled studies described in a 2026 US Wegovy label, 3.3% of people receiving the 2.4 mg injection reported hair loss, compared with 1% receiving placebo. Weight reduction was associated with these reports, but that does not establish the cause of any individual’s hair loss.12
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What did the trials actually find?
In the pooled studies 2, 3 and 4 in the 2026 US label, about 3.3 in 100 people receiving Wegovy (semaglutide) 2.4 mg injection reported hair loss, versus 1 in 100 receiving placebo. That is an absolute difference of about 2.3 reports per 100 people in those studies. These are reported adverse reactions, not a measurement of how much hair each person lost. Other formulations, doses and populations can have different results.1
What about tirzepatide?
The 2026 US Zepbound label also reports hair loss associated with weight reduction. In its pooled studies 1 and 2, it was reported by 7.1% of female and 0.5% of male participants receiving tirzepatide, versus 1.3% and 0% respectively with placebo. These subgroup figures are not a direct comparison with Wegovy: populations and studies differ. Sex categories reflect the label’s reporting and do not predict an individual outcome.
A 2026 US health-record study asked a different question in adults with type 2 diabetes. It compared people starting GLP-1-related medicines with people starting other diabetes medicines, including SGLT-2 inhibitors. In that comparison, the researchers found more recorded diagnoses of hair loss in the GLP-1 group after statistical adjustment; the estimated hazard was 1.37 times that of the SGLT-2 group. The study was observational, not randomized: differences between patients or their care may still influence the result, and only diagnosed hair loss captured in records was counted. It cannot show the mechanism, predict a person’s outcome or establish the same risk for people without diabetes. The study received partial US National Institutes of Health funding.25
Why might hair shedding happen?
Hair shedding can follow a physical stress, including substantial weight loss, often becoming noticeable a few months later. Dermatologists call one form telogen effluvium. Other forms of hair loss, illness, medicines, thyroid problems and nutritional deficiencies can have different causes. The trial association with weight reduction does not establish the precise mechanism or mean every case is temporary. Persistent, patchy or concerning loss deserves clinical assessment.3
Will biotin or another supplement help?
A deficiency may need attention, but hair loss alone does not establish a deficiency or prove that a supplement will help. Tell a clinician about medicines, supplements, changes in eating and the timing and pattern of shedding. Some biotin-containing supplements can interfere with laboratory tests, including certain troponin tests used in heart assessment. Explore what the evidence says about biotin and iron and deficiency before treating a marketing claim as a diagnosis.4
What should I discuss with a professional?
A prescriber or dermatologist can consider the pattern, other possible causes and whether tests are appropriate, alongside the benefits and risks of the exact medicine. Do not change prescribed treatment solely on the basis of a general article. The semaglutide and tirzepatide profiles explain the wider evidence and product differences. Trial averages cannot tell an individual whether shedding will occur or how long it will last.3
Sources, kept close.
Selected supporting sources; this is not a complete literature review.
- Wegovy prescribing information, 2026U.S. Food and Drug Administration / Novo Nordisk · US product label; pooled clinical trial safety reports
- Zepbound prescribing information, 2026U.S. Food and Drug Administration / Eli Lilly · US product label; pooled clinical trial safety reports
- Do you have hair loss or hair shedding?American Academy of Dermatology · Professional association patient guidance
- Biotin interference with troponin lab testsU.S. Food and Drug Administration · Regulator safety information
- Risk of hair loss associated with glucagon-like peptide-1 receptor agonists in adults with type 2 diabetes: target trial emulationThe BMJ · Observational electronic-health-record study