Mounjaro & Zepbound Hair Loss: Causes and What Helps

By Orla Rose · Evidence checked 13 September 2026 · For adult UK and US readers

A brush full of hair can undo a morning rather quickly. Even if you were told shedding might happen, seeing it is different from reading about it. You may be tempted to order a supplement, stop washing your hair or search for a date when everything will grow back.

The useful first step is to separate what the medicine trials recorded from what a clinician can find out about your scalp. Neither “the medicine definitely damaged your hair” nor “it is definitely nothing to do with treatment” is a sound conclusion from the bathroom floor.

Mounjaro and Zepbound both contain tirzepatide. In the UK, Mounjaro has a weight-management indication. In the US, Zepbound is the tirzepatide brand approved for chronic weight management; Mounjaro is a diabetes medicine. Hair-loss figures need to be attached to the population and product information they came from.

How often was hair loss reported in the trials?

Hair-loss reports in weight-management trials; these are percentages, not predictions
Source and population	Tirzepatide	Placebo
UK Mounjaro information: pooled SURMOUNT-1, -2 and -3 studies	4.9%	1.0%
US Zepbound information: pooled Studies 1 and 2, 5 mg group	5%	1%
Same US pool, 10 mg group	4%	1%
Same US pool, 15 mg group	5%	1%

Sources: UK Mounjaro, section 4.8 and US Zepbound, section 6.1. The UK and US summaries use different pools. Their small numerical differences do not show that living in one country changes the risk.

The US safety pool comprised two randomised, double-blind, placebo-controlled trials lasting up to 72 weeks, involving adults with obesity or overweight, with or without type 2 diabetes. There were 2,519 tirzepatide-treated participants and 958 receiving placebo. The individual treatment groups contained 630, 948 and 941 people. These were Lilly-sponsored studies.

The UK figures differ by 3.9 percentage points: 4.9 minus 1.0. Expressed on the same scale, that is about 49 reports per 1,000 treated people versus 10 per 1,000 receiving placebo. Those are rate equivalents, not a claim that the trials each enrolled exactly 1,000 people.

The US label describes the hair-loss reactions as associated with weight reduction. An adverse-event table cannot establish the mechanism in an individual, distinguish every type of hair loss or tell you precisely when regrowth will occur.

What is telogen effluvium?

Telogen effluvium is increased shedding after a disruption to the normal hair cycle. The British Association of Dermatologists lists marked weight loss and extreme dieting among possible triggers, alongside illness, surgery, childbirth, major stress and medication changes. Shedding can begin around three months after a trigger, so the relevant history may go further back than your most recent injection. BAD patient guidance.

It often affects the scalp more generally rather than creating one discrete bald patch. That is a clue for assessment, not something you can confirm by counting hairs in the sink. Other forms of thinning can appear at the same time.

A clinician may ask about the months before shedding started, examine your scalp and consider tests for causes such as iron deficiency or thyroid disease. Which tests make sense depends on your history. A large private “hair panel” is not automatically the best first purchase.

What else could be causing the change?

The American Academy of Dermatology distinguishes excessive shedding from hair loss caused by a problem that stops hair growing. Hereditary thinning, some treatments, tight hairstyles and harsh products are among the possibilities it describes. More than one issue can coexist. AAD: hair loss or hair shedding?.

Tell the clinician if your parting has gradually widened over years, if the change is sudden, or if short broken strands are more noticeable than shedding from the root. Mention scalp pain, itching, scaling or patches. These details are more useful than labelling everything “Mounjaro hair”.

You do not need to know which category fits before booking. That is what the appointment is for. The fact that someone in an online group had temporary shedding cannot establish that your situation is the same.

Should you buy biotin, collagen or a hair supplement?

A shedding symptom does not prove a deficiency. Before buying several products, ask whether your diet or medical history suggests a specific gap and whether testing would change the advice.

Biotin is heavily promoted for hair, but the NIH Office of Dietary Supplements says there is little scientific evidence supporting the hair, skin and nail claims made for supplements. Biotin can also interfere with some laboratory tests, including tests used to assess thyroid function. Tell the clinician and laboratory about supplements you take; follow their instructions before blood testing. NIH biotin fact sheet.

Do not assume a “natural” product is irrelevant to a medication review. Photograph the front and ingredient list, particularly if you take a hair formula alongside a multivitamin. It makes the amounts and any overlap easier to see.

Collagen powder, a branded shampoo or a hair vitamin cannot be promised to prevent or reverse treatment-associated shedding. If a product claim interests you, ask what outcome was actually studied, in whom, and whether the evidence concerns your type of hair loss. A testimonial and a glossy before-and-after photograph do not answer those questions.

What does sensible food support look like?

The question is whether you can eat adequately across the day, rather than whether you have found the perfect “hair food”. If lunch has quietly become half a yogurt and dinner is regularly abandoned because of nausea, tell your care team. You deserve help with the eating difficulty itself.

The joint professional nutrition advisory for GLP-1 therapy emphasises assessment of nutritional adequacy and management of barriers to eating. It is guidance drawn from evidence and clinical expertise, not a trial showing that a particular menu restores hair.

For everyday planning, keep a few foods you can manage without much preparation. Eggs on toast, tofu with rice, yogurt with oats or beans in a baked potato may be workable options, depending on your preferences and prescribed dietary restrictions. These are meal ideas, not a complete diet or a regrowth prescription.

If you struggle with small portions, our low-appetite food guide explains how to make eating more manageable. A dietitian can help assess the whole diet rather than asking you to chase a protein number while everything else falls away.

How can you look after your hair meanwhile?

Choose care you can live with: gentler brushing, less heat and avoiding styles that pull tightly. BAD's self-care advice recommends limiting harsh chemical treatments as well. This may reduce additional stress and breakage; it is not evidence that you can shorten a shedding cycle by finding the right brush.

If monitoring helps, take an occasional photograph in similar lighting with the same parting. If it makes you inspect your scalp repeatedly, leave the camera alone and describe the change at your appointment. You do not need a daily evidence folder to justify being concerned.

You may also prefer a different hairstyle while things are being assessed. That is a practical choice, not an admission that the problem is permanent. It is fine to ask your hairdresser to be gentle and leave the medical explanations to a qualified clinician.

When should you seek an assessment?

Arrange a GP, primary-care or dermatology appointment if the change concerns you, especially with patchy loss, scalp symptoms, visible thinning, ongoing shedding or other changes in your health. You do not have to wait six months. “Chronic telogen effluvium” is a clinical description, not a waiting period for permission to seek help.

UK: a GP can assess possible causes and discuss referral where appropriate. US: your primary-care clinician or a dermatologist can assess you; check whether your insurance requires a referral. Also tell the clinician prescribing Mounjaro or Zepbound so the treatment review includes the change.

Bring the timeline, your medication and supplement list, any illness or major changes in recent months, and a brief description of how eating has been. You could say: “I've noticed increased shedding since this date. Could you assess the pattern and whether any tests or a dermatology opinion would help?”

What else do readers ask about GLP-1 hair loss?

Will all of the hair grow back?

That depends on the cause. Telogen effluvium often improves, but some people have another condition alongside it. General recovery ranges cannot promise your eventual thickness or a particular month when shedding will stop.

Does hair loss mean treatment is working particularly well?

No. It is not a target, a badge of success or a reliable measure of treatment benefit. Record it as a symptom, not as proof that you should tolerate more weight loss or reduce food further.

Should you stop Mounjaro or Zepbound to protect your hair?

Discuss the change with your prescriber. An article cannot decide whether medication is contributing or whether your treatment should change. The AAD specifically advises talking to a clinician before stopping a medicine suspected of causing hair loss.

Can the tirzepatide percentages be used for Ozempic or Wegovy?

No. Semaglutide has its own product information and trial populations. Even two products containing the same ingredient can have different studied doses and indications. Use the evidence for the exact question you are asking.

Sources

References are linked beside the relevant information in this article.