Mounjaro Hair Loss: Causes, How Long It Lasts & What Helps

Noticing increased hair on your pillow or in the shower? It's a recognised side effect of Mounjaro. Hair loss is listed in the product information as a side effect, and the MHRA received 940 Yellow Card reports that linked tirzepatide to hair loss in 2026/26.

But evidence so far doesn't suggest that Mounjaro itself causes hair loss. Instead, it's due to the body responding to rapid weight loss (also known as telogen effluvium - a reversible side effect).

In this guide, we'll cover everything you need to know about Mounjaro and hair loss, including how long it lasts, what helps, and when you should speak to a doctor.

Does Mounjaro Cause Hair Loss?

Technically yes, Mounjaro can result in weight loss and alopecia is listed as a side effect in the Mounjaro weight management SmPC, impacting up to 1 in 10 users.

While it's listed in the weight loss SmPC, Mounjaro isn't in the type 2 diabetes SmPC as weight loss in these trials was usually lower.

Because both groups use the same medication, hair loss is attributable to rapid weight loss treatment, rather than the medication itself.

Hair Loss From Mounjaro Statistics

• In clinical trials, hair loss impacted 4-6% of participants taking Mounjaro at higher doses. Under 1% of the placebo group identified hair loss (SURMOUNT-1 and SURMOUNT-2).
• While only 0.5-1% of men experienced hair loss in SURMOUNT-1, the numbers were higher among women, with 5-7% reporting the side effect.
• There were 541 Yellow Card reports linking tirzepatide in 2025 and 399 in the first part of 2026, making it one of the most reported adverse effects.

Key Takeaway: Instead of evidence pointing to Mounjaro as directly responsible for hair loss, it suggests alopecia is a reaction to how your body responds to rapid weight loss.

What Is Actually Causing the Hair Loss? Telogen Effluvium Explained

Telogen effluvium is a temporary condition that causes diffuse shedding. It occurs due to physical stressors the body responds to, including rapid weight loss. There are three main phases of the hair growth cycle:

1. Anagen (Growth Phase): The cells in your roots divide and create new hair. This stage lasts ~2–6 years.
2. Catagen (Transition Phase): The follicles shrink and detach from your blood supply. The average person will lose up to 2% of their hair.
3. Telogen (Resting Phase and Shedding): Old hair rests and will fall out, making room for new strands. This stage impacts 10-15% of your hair.

Hair Loss on Mounjaro is Often Caused By:

• Losing Weight Rapidly: Research shows that hair loss typically occurs after losing 15.2% of your body weight (~3.5 kg/month). Since Mounjaro can cause 20–22.5% total weight loss, many patients will meet this threshold.
• Reduced Dietary Intake: When someone eats less food, their body receives fewer nutrients, which can impact hair growth - especially when this leads to deficiencies in Vitamin D, iron, zinc, protein, and biotin.
• Higher Cortisol: Cortisol is linked to telogen effluvium, and weight loss can cause higher levels.
• Hormonal Changes: Weight loss can interfere with oestrogen, insulin, and the thyroid, which can interrupt the hair growth cycle.

No evidence directly links Mounjaro and hair loss, with pharmacovigilance analysis giving tirzepatide a 1.73 ROR (Reporting Odds Ratio). This is confirmed in Godfrey et al. (JEADV 2025). In 2026, an analysis by Lee and Kim found no significant signal.

Put simply, if a person achieves the same amount of weight loss through diet and exercise alone, they could expect to experience a similar telogen effluvium rate.

What Does Mounjaro Hair Loss Look Like?

Telogen effluvium doesn't instantly cause bald patches or huge clumps of missing hair. Instead, most people notice that they lose more hair than normal. For example, you might notice more hair in the shower drain or on your brush, or there's less scalp volume.

Diffuse shedding is the main symptom of telogen effluvium, meaning hair loss occurs across your scalp rather than in one area.

So, if you notice thinning around the crown or a receding hairline, these aren't usually side effects of the medication. Despite the shedding, your scalp should still be healthy. A doctor should assess changes, including redness and itching.

When Does Mounjaro Hair Loss Start and How Long Does It Last?

In most cases, you won't notice hair thinning or shedding when you first start using Mounjaro. Instead, it generally occurs around three months of treatment because the hair enters the resting phase before it begins to shed.

According to the British Association of Dermatologists, telogen effluvium hair shedding lasts for between three and six months. Regrowth generally happens within three to six months of the shedding stage. So, once your body gets used to Mounjaro (around 6-9 months of treatment), it's easier to manage hair loss.

Should I Stop Taking Mounjaro Because of Hair Loss?

As mentioned previously, the hair loss cycle takes time, so stopping Mounjaro injections won't instantly reverse it. Your hair was pushed into telogen months ago, and shedding will happen, regardless of whether you stop treatment.

Also, stopping Mounjaro can result in weight gain, which increases the risk of health conditions. It's best to speak to a healthcare professional or your prescriber if you're thinking of stopping weight loss injections, as they can explore lowering your dose or increasing the time between increases.

Important: If you experience severe hair loss or psychological symptoms, you should speak to your prescriber. Some people may find that the negative impact of further hair loss outweighs the benefits of weight loss, and a prescriber can help you explore your options.

What Actually Helps: Evidence-Based Prevention and Management

When you're experiencing hair thinning and shedding, it's tempting to look for solutions. However, hair growth formulas are rarely effective for telogen effluvium. Instead, focus on identifying the trigger and accepting that the condition can be caused by weight loss.

Here are the things that might help reduce the rate of hair shedding:

• Protein: Because hair is around 90% keratin, a low protein intake can speed up hair loss. Increasing your daily intake to 1.2 to 1.6 grams of protein per kg of your body weight can be beneficial. Good protein sources include lean meats, tofu, Greek yoghurt, and lentils.
• Iron: Telogen effluvium is linked to low iron levels (PubMed). Iron deficiency is more common in women, and supplements or increased dietary intake can help. However, ask your GP for a blood test before taking iron supplements.
• Vitamin D: All adults in the UK should take a 10 microgram Vitamin D supplement during the autumn and winter, but individuals using Mounjaro can benefit from a year-round supplement.
• Zinc: Low zinc levels are also linked to hair loss (NCBI). While zinc supplements can help, you should have a blood test to check your levels first, as too much zinc can impact copper absorption.
• Eat Enough: Mounjaro decreases your appetite, which can lead to a lower calorie intake. Follow your prescriber-recommended diet and avoid large calorie deficits. A balanced diet should consist of healthy fats, protein, complex carbohydrates, and fibre.
• Minoxidil: If you experience significant hair loss, topical Minoxidil 5% can be beneficial, but it won't treat telogen effluvium. Instead, it may speed up regrowth for both men and women. Formulas designed for women are available, but you should speak to a dermatologist or your GP before using Minoxidil.
• Be Gentle: Taking steps to protect your hair, including avoiding heavy brushing and chemical treatments, can reduce the effects of mechanical hair breakage.

What Doesn't Help: The Biotin Myth and Other Misconceptions

Biotin (Vitamin B7) is one of the most heavily marketed supplements for hair loss, but it's only effective if someone has a B7 deficiency, which is rare in the UK. There's no evidence that biotin can treat telogen effluvium - especially if the cause is linked to other deficiencies and rapid weight loss.

Some Mounjaro users will need regular thyroid tests, and biotin supplements can affect the results (per the MHRA safety update).

Stopping Mounjaro treatment is also unlikely to instantly stop hair loss, and you're at risk of regaining any lost weight.

While it might be tempting to spend money on supplements that promise to support hair health, the most important steps are eating more protein and testing your iron levels.

When to See a GP or Dermatologist

If any of the following occur, you should see a dermatologist or your GP:

• The hair loss is patchy with bald spots, as it could mean you have an autoimmune condition.
• You're experiencing scalp symptoms, including burning, itching, and redness.
• You feel cold, have unexplained weight changes, and are lethargic (all of which could point to a thyroid condition).
• It's been six months, and you're still experiencing hair loss.
• You're experiencing psychological distress, as your GP may be able to refer you to a dermatologist.

Ask your GP for a full blood count that includes ferritin testing and thyroid function testing. Perimenopausal women should also ask for FSH/oestrogen tests.

Remember, both healthcare professionals and patients can report any changes to the MHRA Yellow Card Scheme. It means that specialists can continue monitoring that side effect.

Will My Hair Grow Back?

In the majority of cases, yes - because telogen effluvium doesn't stop your hair follicles from working. Instead, they move through the hair cycle differently, and hair will begin growing again once it settles.

Once hair begins to grow again, you might initially see short hairs along the parting or hairline, as it takes longer for volume to return. If someone already has the signs of female or male pattern hair loss, they might notice that it becomes more prominent once telogen effluvium occurs.

If the shedding settles but you still notice that certain areas are becoming thinner, seeing a dermatologist can be beneficial. However, patience is key, and dermatologists advise that the condition improves over time.