Hair Loss and Thinning on Mounjaro and GLP-1 Weight Loss Injections – What You Should Know

By Jaydev Varsani – Clinical Prescribing Pharmacist, Murrays Chemist

Many people starting GLP-1 injections such as Mounjaro (tirzepatide), Wegovy, or Ozempic (semaglutide) are achieving outstanding results — losing weight, improving blood sugar, and often feeling healthier and more confident than they have in years.

But for some, there’s a surprise along the way: increased hair shedding or thinning.

If you’ve started noticing more hair on your brush or pillow since beginning a GLP-1 treatment, you’re not alone. Although this side effect is not particularly common, it’s being reported often enough that patients are rightly curious — and sometimes concerned.

Here’s what we know so far, why it happens, and what can be done about it.

Understanding Hair Growth and Shedding

Your hair grows in cycles, and each follicle follows its own rhythm:

• Anagen (growth phase) – where hair actively grows for years

• Catagen (transition phase) – a brief resting stage

• Telogen (shedding phase) – where old hair is released

Normally, only about one in ten hairs is in the telogen phase.
However, when the body experiences physical or emotional stress — such as illness, major weight loss, or hormonal changes — many follicles can shift into this resting phase prematurely.

This condition is called Telogen Effluvium, and it’s the most likely reason some patients experience temporary hair loss while on GLP-1 therapy.

Does Mounjaro or Wegovy Actually Cause Hair Loss?

Hair loss isn’t listed as a standard side effect in the product information for Mounjaro or other GLP-1s. However, real-world data and patient reports tell a slightly different story.

• In clinical studies, around 4–6% of tirzepatide users reported hair loss compared with less than 1% of those on placebo.

• A similar trend has been observed with semaglutide (Wegovy/Ozempic), though less frequently.

• Post-marketing reports and patient experiences suggest the issue is genuine, even if relatively uncommon.

It’s important to understand that rapid weight loss itself can trigger hair shedding, regardless of the medication used. The link, therefore, may be indirect rather than a direct side effect of GLP-1 drugs.

Why Hair Loss Happens During GLP-1 Therapy

Several mechanisms can overlap. The most common contributors are:

1. Rapid Weight Loss and Metabolic Stress

GLP-1s often produce swift and significant weight reduction.
When this happens quickly, the body interprets it as a form of stress and diverts energy away from “non-essential” processes like hair growth.

This leads to temporary shedding a few months after the weight loss starts — a classic telogen effluvium pattern.

2. Nutritional Deficiency and Reduced Intake

Because GLP-1s suppress appetite, some patients unintentionally eat too little.
This can reduce intake of nutrients vital for hair growth, such as:

• Protein – essential for keratin production

• Iron and ferritin – crucial for oxygen delivery to hair follicles

• Zinc and selenium – involved in cell growth and tissue repair

• Vitamin D, B12 and folate – support healthy cell turnover

Even mild deficiencies in these nutrients can affect hair growth within weeks.

At Murrays Chemist, we offer a full range of private blood tests on-site to check for these deficiencies — including vitamin D, B12, folate, ferritin, iron studies, thyroid function, zinc, and protein levels.
Results are usually available within 48 hours, allowing us to identify and correct nutritional gaps before they worsen.

3. Hormonal and Endocrine Adjustments

GLP-1 medications influence several hormonal pathways.
They improve insulin sensitivity, can modify stress hormone levels, and may even subtly alter thyroid activity — all of which can impact hair cycling.

• Thyroid hormone shifts are a well-known cause of diffuse hair loss.

• Cortisol and stress hormone changes can also disrupt follicle rhythm.

• Sex hormone rebalancing, particularly reduced androgens in women with PCOS, may temporarily shift the growth pattern before stabilising.

These changes usually correct themselves over time as your body adapts.

4. Physical and Emotional Stress

Any major change in weight, diet, or routine places the body under temporary strain. Combine that with the stress of noticing hair thinning, and cortisol levels can rise — compounding the issue.

5. Underlying or Genetic Hair Thinning

Sometimes the medication simply reveals pre-existing genetic hair loss that was masked by thicker hair volume. In such cases, the timing can make it seem like the GLP-1 caused the issue when it simply uncovered an underlying tendency.

How Common Is It?

In practical terms, around 1 in 20 GLP-1 users may experience some level of hair shedding.
It’s far less common than nausea or constipation, and the vast majority of people see regrowth once weight stabilises and nutritional intake improves.

At Murrays Chemist, where we’ve monitored hundreds of GLP-1 patients, only a small handful have reported noticeable hair loss — and in all cases, recovery occurred within months with appropriate support.

Is Hair Loss from Mounjaro Reversible?

Yes — in almost every instance it is temporary and fully reversible.
Once your body adjusts and nutrient levels are corrected, hair growth returns to normal.

Expect visible regrowth in 3–6 months, with full recovery over 6–12 months.

Patience is essential — hair growth takes time, and panic-stopping your treatment can be counterproductive.

Practical Steps to Prevent or Reduce Hair Loss

1. Prioritise Protein

When your appetite drops, protein intake is usually the first to suffer.
Aim for at least 1g of protein per kilogram of body weight per day, using foods like lean meat, eggs, dairy, pulses, tofu, or protein shakes.

This simple change makes a major difference.

2. Maintain a Balanced, Nutrient-Dense Diet

Focus on quality over quantity.
Include foods rich in iron, zinc, B-vitamins, vitamin D, and omega-3 fats. If you’re unsure what you’re lacking, book a blood test at Murrays Chemist — we can check and discuss the results in a follow-up consultation with our prescribing pharmacist.

3. Avoid Losing Weight Too Fast

Aim for gradual weight loss (1–1.5 kg per week).
If you’re losing faster, we can review your dosage or diet to help stabilise progress. Steadier loss equals less stress on your hair.

4. Check Thyroid and Iron Status

Even subtle thyroid or iron abnormalities can worsen hair thinning.
Our in-pharmacy blood testing service covers thyroid function, ferritin, iron, and vitamin levels — all from a quick blood draw on site.

5. Be Gentle With Your Hair

Avoid heat damage, tight hairstyles, or harsh colouring.
Use a mild shampoo and consider scalp-stimulating serums containing caffeine, peptides, or biotin to support follicle health.

6. Manage Stress and Sleep

Good sleep, regular hydration, and mindful stress management all contribute to recovery.
Remember: hair loss is often a delayed response to stress, not just to diet or medication.

7. Be Patient and Consistent

Hair regrowth doesn’t happen overnight.
Stick to your treatment plan, support your nutrition, and give your follicles time to recover. Most people see progress within months once their body settles into its new rhythm.

When to Seek Advice

Speak to a clinician if:

• Hair loss is sudden, patchy, or comes with scalp irritation

• You’ve had shedding for over 6 months

• You’re feeling unusually tired or weak (signs of anaemia or deficiency)

• You’ve been struggling to eat enough due to nausea or loss of appetite

At Murrays Chemist in Harrow, our pharmacist-led weight loss and wellness clinic can assess your symptoms, run blood tests, and provide a personalised recovery plan.
We also offer biotin injections and IV vitamin therapy to replenish nutrients when required.

Key Takeaways

• Hair loss on GLP-1 therapies is uncommon and temporary.

• It’s usually caused by rapid weight loss, nutritional gaps, or hormonal adjustments rather than the medication itself.

• Regrowth occurs naturally once your weight and nutrition stabilise.

• Maintaining a high-protein diet, balanced nutrition, and regular monitoring can prevent or reduce the risk.

• Blood testing helps identify and correct deficiencies early.

• Be patient — your hair will almost certainly return.

For further guidance or to arrange a review, visit Murrays Chemist, 172 Kenton Road, Harrow (HA3 8BL), or call us on 0208 907 0413 to book a consultation with our clinical pharmacist.

References

1. Drugs.com – Do Ozempic, Wegovy or Mounjaro cause hair loss? (2024).

2. PubMed – Dermatologic complications of GLP-1 receptor agonists (PMID: 39264502, 2024).

3. PubMed – Tirzepatide and hair loss: emerging signal review (PMID: 38741261, 2024).

4. PMC – Semaglutide-associated alopecia: case series and review (PMC11909624, 2024).

5. Medical News Today – GLP-1 side effects and hair loss (2024).

6. Virta Health – Does Ozempic cause hair loss? (2024).

7. American Academy of Dermatology – Telogen effluvium overview (2023).

8. Mayo Clinic – Hair loss causes – Telogen effluvium (2023).

9. NICE – Obesity: identification, assessment and management – GLP-1 agonist use (2023).

10. Murrays Chemist Clinical Services – Private Blood Testing & IV Vitamin Therapy, Harrow (2025).