Noticed more hair in the plughole since starting Mounjaro or Wegovy? You're not imagining it.
Mounjaro hair loss and Wegovy hair loss are both recognised side effects, but the medicine usually isn't attacking your hair directly. It's what fast weight loss does to your hair's growth cycle.
The good news is that this kind of shedding is usually temporary. Below, we look at how common it is, why it happens, how long it lasts and what actually helps, plus when it's worth getting checked.
Shedding on a weight loss injection is common and usually short-lived. Most people don't need to stop treatment because of it.
Does Mounjaro cause hair loss?
Yes, it can. Hair loss is listed as a common side effect of Mounjaro (tirzepatide), which means it can affect up to 1 in 10 people.1
In the weight loss trials, 4.9% of people taking tirzepatide reported hair loss, compared with 1% of people taking a placebo (a dummy injection).1
Those numbers come with some reassurance. The hair loss was mainly mild, most people recovered while they carried on with treatment, and nobody in those trials stopped tirzepatide because of it.1
Some websites still say hair loss isn't a listed side effect of Mounjaro. The current UK prescribing information does list it.1
Around 1 in 20 people in the Mounjaro weight loss trials noticed some hair loss, so you're far from alone if it happens to you.
Does Wegovy cause hair loss?
Wegovy (semaglutide) also lists hair loss as a common side effect.2
In the main trials, 2.5% of people on the 2.4 mg dose reported hair loss, compared with 1% on placebo. On the higher 7.2 mg dose, that rose to 5.3%.2 As with Mounjaro, it was mainly mild and most people recovered without stopping treatment.2
One detail stands out. Hair loss was reported more often in people who lost 20% or more of their body weight.2 That's a big clue to what's really going on.
A quick word on comparing the two. These figures come from separate trials with different people and doses, so they can't tell you which medicine is "worse" for your hair. If you take semaglutide as a tablet, our guide to Wegovy tablets covers how they work.
Real-world data points the same way. A 2026 study in The BMJ of more than 27,000 adults with type 2 diabetes found that people starting a GLP-1 medicine had a 37% higher relative risk of hair loss than people starting a different type of diabetes medicine.3 The extra risk was mainly non-scarring hair loss, the kind where follicles stay intact, and the overall risk stayed low.3
The more weight you lose, the more likely your hair is to react. That link is the key to understanding why it happens.
Why do Mounjaro and Wegovy cause hair loss?
The main culprit is a type of shedding called telogen effluvium. It sounds technical, but the idea is simple.
Your hair grows in cycles. At any one time, around 85% of the follicles on your scalp are growing hair and around 15% are resting. A resting hair stays put for two to four months before a new hair pushes it out.4
A big change in the body can push far more follicles into the resting phase at once. Significant weight loss and extreme dieting are well-known triggers, alongside illness, surgery, stress and starting a new medicine.4 Around three months later, all those resting hairs start to fall out.4
That delay is why Mounjaro hair loss can seem to come out of nowhere. The trigger happened weeks before you started noticing those extra strands falling out.
Eating less can play a part too
These medicines help you lose weight by dialling down your appetite. That's the point, but eating much less can also mean getting less of the nutrients your hair relies on.
The BMJ researchers noted that rapid weight loss can lead to low iron or zinc, which can disrupt the hair growth cycle.3 The NHS also lists iron deficiency as a cause of temporary hair loss.5
Think of it as your body pressing pause on hair growth while it adjusts to a big change. It's a delayed reaction, not damage to your follicles.
Is Mounjaro hair loss permanent?
Usually not, and the same goes for shedding on Wegovy. Telogen effluvium normally gets better on its own, without any treatment.4
The shedding phase tends to last three to six months. After that, new hair starts to grow, although it can take many more months for your hair to feel as full as before.4 Taking medicine won't make that regrowth happen any faster.4
Two things are worth knowing:
- It can come back - shedding can return if an underlying cause, such as low iron, isn't sorted out.4
- It can reveal pattern hair loss - sometimes a bout of shedding is the first sign of male or female pattern hair loss, which is a separate, longer-term condition.4
Regrowth after Mounjaro hair loss is gradual. Judge your hair over months rather than weeks, and try not to read too much into a single bad wash day.
How to stop hair loss on Mounjaro or Wegovy
There's no way to switch off this kind of shedding overnight. But you can give your hair the best chance of recovering, and avoid making things worse.
- Eat enough protein and iron - a balanced diet with iron-rich foods, protein, fruit and vegetables may help.4 Small, protein-first meals can make this easier when your appetite is low.
- Do not crash diet on top of your medication - extreme dieting is a trigger in its own right, so there's nothing to gain from cutting back further than your prescriber advises.4
- Be gentle with your hair - go easy on brushing, tight hairstyles, bleaching and heat styling.4
- Stop smoking if you smoke - cigarette smoke can make hair loss worse.4
- Consider a supplement if your diet is restricted - for example, if you eat a vegan or vegetarian diet.4
- Use volumising products - a volumising shampoo or hair fibres can make thinning less noticeable while you wait.4
Worried enough to think about stopping your injection? Speak to your prescriber first. In the trials, most people's hair recovered while they stayed on treatment.1 2
Do not stop, skip or lower your dose to protect your hair without speaking to your prescriber first.
What about hair loss treatments?
Minoxidil and finasteride treat pattern hair loss rather than weight loss shedding.5 But if shedding has unmasked pattern hair loss, they may be worth a conversation with a pharmacist or GP.
- Minoxidil - a lotion or foam you apply to your scalp, such as Regaine for Men or Regaine for Women. It can be used for male and female pattern hair loss.5
- Finasteride - a daily tablet for men only. Women should not use it.5 The MHRA warns it's linked to low mood, depression, suicidal thoughts and sexual side effects. If you develop depression or suicidal thoughts while taking it, stop treatment and seek medical advice.6
Both only work for as long as you keep using them, and they don't work for everyone.5 Our guide to which hair loss treatment works best compares the options in more detail.
When should you see a GP about hair loss?
Shedding on a weight loss injection usually isn't anything to worry about. But hair loss can have other causes, so it's worth getting checked if:
- Your hair is coming out in patches rather than thinning all over.4
- Shedding hasn't eased after six months.4
- You feel generally unwell or have other new symptoms
- You're worried, or it's affecting how you feel about yourself.5
A GP can look at your scalp and may arrange a blood test to rule out things like thyroid problems or low iron.4 If hair loss is affecting your wellbeing, tell them. They may be able to help you get some counselling or support.5
It's also worth letting your prescriber know about any side effects you notice during treatment.
Patchy hair loss, or shedding that drags on beyond six months, isn't typical of weight loss shedding and should be checked by a GP.
Frequently asked questions
When does hair loss start on Mounjaro?
Hair loss on Mounjaro usually shows up a few months into treatment rather than straight away. The shedding linked to rapid weight loss, called telogen effluvium, tends to start around three months after the trigger. So it’s common to notice more hair in your brush or the shower a while after the weight starts coming off, even though the process began weeks earlier.
Does Mounjaro cause hair loss in women?
It can affect anyone. The shedding linked to weight loss affects men and women equally, and it usually settles on its own within a few months. If it reveals female pattern hair loss, minoxidil is an option women can use. Women should not use finasteride, so speak to a pharmacist or GP before starting any hair loss treatment.
What vitamins help with hair loss on Mounjaro?
No vitamin has been shown to stop shedding caused by weight loss. The most useful step is eating enough protein and iron-rich foods while your appetite is low. If a blood test shows your iron is low, your GP can advise on treatment. Biotin contributes to the maintenance of normal hair, and a supplement may be worth considering if your diet is restricted, so ask a pharmacist.
Is hair loss worse on Mounjaro or Wegovy?
There’s no head-to-head trial to answer this. In separate trials, hair loss was reported by 4.9% of people on Mounjaro, and by 2.5% on Wegovy 2.4 mg and 5.3% on the 7.2 mg dose. The trials involved different people and doses, so the figures can’t be compared directly. With both medicines, it was mainly mild and usually settled without stopping.
Can you stop Mounjaro hair loss overnight?
No. Once hairs have moved into the resting phase, they’ll shed on their own schedule, and medication won’t speed up regrowth. What you can do is support recovery: eat enough protein and iron, avoid crash dieting on top of your treatment and be gentle with your hair. Shedding usually eases within three to six months, then new hair starts to grow.
References
- Eli Lilly and Company Limited. Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen: Summary of Product Characteristics. Electronic Medicines Compendium; 2026. medicines.org.uk/emc
- Novo Nordisk Limited. Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen: Summary of Product Characteristics. Electronic Medicines Compendium; 2026. medicines.org.uk/emc
- Tang H, et al. Risk of hair loss associated with glucagon-like peptide-1 receptor agonists in adults with type 2 diabetes: target trial emulation. BMJ. 2026;394:e100077. doi:10.1136/bmj-2026-100077
- British Association of Dermatologists. Telogen effluvium. BAD Patient Hub; 2025. skinhealthinfo.org.uk
- NHS. Hair loss. NHS website; 2024. nhs.uk
- Medicines and Healthcare products Regulatory Agency. MHRA strengthens safety warnings for finasteride and dutasteride. GOV.UK; 2026. gov.uk
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.