Does Wegovy Cause Hair Loss? What the Clinical Evidence Shows

What the trial data actually recorded

The clearest starting point is the STEP 1 trial published in the New England Journal of Medicine, which followed 1,961 adults over 68 weeks on semaglutide 2.4mg. Hair loss was reported as an adverse event in around 3% of people on the active treatment compared with roughly 1% on placebo. That gap confirms semaglutide plays some role, but it also tells you that the large majority of participants did not report it at all. The trial population lost an average of around 15% of their body weight (a substantial change in a relatively short time) and rapid weight loss itself is a well-established trigger for temporary hair shedding, independent of any medicine. Separating the drug effect from the weight-loss effect is genuinely difficult, which is why the honest answer involves both, and anyone looking for a closer examination of that question can read whether semaglutide causes hair loss and what the evidence actually shows. For a fuller picture of how Wegovy's side-effect profile looks overall, the complete Wegovy side effects page sets out what the data shows across the range of reported events.

Can Wegovy cause hair loss? Yes, in a subset of people. Whether it does in any individual depends on factors including how fast weight is lost, protein intake, underlying health, and genetics.

Why the hair sheds, and why it usually grows back

The mechanism is almost always telogen effluvium. Hair follicles cycle through growth, transition and rest phases. Physical stressors (calorie restriction, rapid weight change, illness, surgery) can push a larger-than-normal proportion of follicles into the resting (telogen) phase simultaneously. Two to four months later, those hairs shed in a cluster, which can look alarming but reflects past stress rather than ongoing damage. The follicles themselves are intact. Once the stressor eases and nutrition stabilises, the growth phase resumes. Most people who experience this pattern on a GLP-1 medicine find the shedding slows and then stops within a few months, with regrowth following. The detailed guide to hair loss and Wegovy covers the timeline and what tends to help. Protein adequacy matters here: getting enough protein each day supports hair follicle maintenance, and it is one of the reasons prescribers recommend not cutting protein while reducing overall calories on treatment.

Women may notice this pattern more acutely at certain life stages. There is a separate look at how Wegovy-related hair loss presents specifically in women for anyone who wants that angle explored further.

When to get medical help and how to report it

Most shedding on Wegovy follows the telogen effluvium pattern described above and resolves without intervention. There are situations, though, where hair loss warrants prompt medical attention. Speak to your GP or prescriber if: the shedding is severe or spreading in patches rather than diffuse thinning; it began before you started Wegovy or before significant weight loss occurred; it is accompanied by fatigue, cold intolerance or other symptoms that might suggest thyroid dysfunction; or it does not slow within three to four months of a stable dose. These presentations may point to a separate underlying cause that needs investigating in its own right. The MHRA Yellow Card scheme lets patients and healthcare professionals report suspected side effects from any medicine, including Wegovy, doing so contributes to the ongoing safety monitoring that all medicines under active surveillance receive. Wegovy carries a Black Triangle (▼) status, meaning the MHRA actively collects additional data on it. Reporting unusual or significant side effects helps build that picture for everyone taking the medicine. If you are unsure whether what you are experiencing is related to the treatment, the safest step is always to contact your prescriber rather than stopping the injection without guidance.

Broader semaglutide and hair-loss context

Semaglutide is also the active ingredient in Ozempic, which is licensed for type 2 diabetes rather than weight loss, and hair shedding has been reported across both formulations, consistent with the idea that weight change and calorie restriction are the primary driver rather than any property unique to the weight-loss licence. There is also a newer oral semaglutide option; readers curious about whether semaglutides as a class cause hair loss will find that broader comparison useful. The NHS semaglutide medicines page lists hair loss among known side effects and advises telling your doctor or pharmacist if you experience it. That is straightforward, practical guidance: note it, report it, and get it assessed rather than quietly tolerating something that might have a simple fix or, occasionally, a separate explanation. Our prescribers discuss side effects including hair changes as part of every consultation, not as a footnote, but as a practical conversation about what to watch for and what to do if it happens. If you would like to explore whether semaglutide is suitable for you, check your eligibility with a free consultation and a prescriber will review your full picture the same day.