Wegovy and hair loss: is thinning hair a side effect?

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Is there a connection between Wegovy and hair loss? Explore the link between semaglutide and thinning hair.

If you've noticed more hair than usual in the shower drain or your hair brush after starting Wegovy, you may not be imagining things. While hair loss isn't officially listed as a side effect of Wegovy, people have been talking about a possible link.

Let's explore what we know about Wegovy and hair loss, and what you can do if it's happening to you.

Is hair loss a known side effect of Wegovy?

Wegovy is a weight loss injection containing semaglutide, a GLP-1 receptor agonist. Semaglutide helps regulate blood sugar, curb cravings, slow digestion and promote feelings of fullness.

Wegovy's side effects, including nausea, constipation and fatigue, are well-documented. However, hair loss doesn't appear on the official list.

That said, a 2025 study found that a small number of people taking semaglutide reported hair thinning or shedding.¹ While that report made headlines, the researchers clarified something important: semaglutide doesn't directly cause hair loss.

So, why is it happening to some people?

It's not the drug, it's the weight loss.

The link between weight loss and hair thinning has been recognised for decades. People who lose a significant amount of weight quickly – whether through diet, medication or surgery – sometimes experience hair shedding.

The hair loss is usually caused by a condition known as 'telogen effluvium'. It occurs when the body experiences stress or a major change, including rapid weight loss. As a protective response, the body diverts resources away from non-essential functions like hair growth. That's so it can focus on keeping your most important organs and systems running properly.

Hair follicles enter a resting phase, which eventually leads to increased shedding. It's no fun at all – but it's usually only temporary. The follicles aren't damaged, and hair tends to regrow within three to six months.

So, when it comes to semaglutide hair loss, it's usually the result of your body adjusting to weight changes. It's not a direct effect of the medication.

Does the research support this?

The landmark STEP 1 trial, published in The New England Journal of Medicine, studied the effects of semaglutide for weight loss in people without diabetes.

Picture of a Person doing medical research.

Participants receiving weekly 2.4mg doses of semaglutide lost an average of 14.9% of their body weight over 68 weeks.² That's a significant amount – and this kind of rapid change is known to trigger telogen effluvium in some people.

However, if hair loss occurred in any of the participants, the researchers didn't consider it notable enough to include in the study. Nor did Novo Nordisk, Wegovy's manufacturer, consider it a significant enough risk to list it as a side effect.

What about Mounjaro?

Hair loss is listed as a possible side effect of Mounjaro (tirzepatide), another GLP-1 receptor agonist.

Mounjaro has shown even greater weight loss results than Wegovy, which may explain why hair loss is mentioned more often.³ Again, this is tied to the speed and extent of the weight loss, not the medication directly impacting hair follicles.

Can you prevent semaglutide-related hair loss?

There's no guaranteed way to prevent telogen effluvium, but supporting your hair and overall health may help reduce your risk.

Here are some tips that may help you avoid hair loss when losing weight:

Eat enough protein – it's essential for healthy hair growth.
Make sure you're getting enough iron, zinc, B12 and other key nutrients.
Avoid crash dieting or skipping meals.
Consider a multivitamin if your care team recommends it.
Be gentle with your hair – avoid harsh bleach, tight hairstyles or excessive heat styling.

If your hair loss continues or becomes severe, speak to your prescriber. Sometimes, an underlying issue like low iron or thyroid imbalance can contribute to the problem.

How SemaPen can help

At SemaPen, we understand that weight loss isn't just about numbers on a scale – your overall well-being is what's most important.

Our programmes provide private access to Wegovy (semaglutide) or Mounjaro (tirzepatide) with clinical oversight, smart scale tracking and expert guidance. If you experience side effects like hair loss, we can adjust your dosing pace and explore nutritional support. This means you can stay on track without compromising your confidence.

If you've been worried about semaglutide side effects or are simply looking for a more supportive experience, explore our weight loss programmes today. Alternatively, you can take our online medical consultation to find out instantly if you're eligible.

Sources

1. Sodhi, M. et al. (2025) "Risk of Hair Loss with Semaglutide for Weight Loss" [Preprint] medRxiv https://doi.org/10.1101/2025.02.23.25322568

2. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

This article was reviewed and approved by Alice Fletcher, Lead Bariatric Dietitian, on 31 July 2025.

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