Side Effects · 20 March 2026 · 8 min read

Hair Loss on Wegovy and Mounjaro — Why It Happens and How to Stop It (UK 2026)

Hair loss affects 3–6% of GLP-1 users in the UK. It's almost always temporary and caused by rapid weight loss, not the medication itself. Here's why it happens and exactly what to do about it.

Last updated: March 2026 | glp1guide.live

If you've noticed more hair in the shower drain or on your brush since starting Wegovy or Mounjaro, you're not imagining it — and you're definitely not alone. Hair loss is one of the most talked-about side effects in UK GLP-1 support groups, and it causes a lot of unnecessary panic.

Here's the good news: in the vast majority of cases, it's temporary, it's treatable, and it doesn't mean you need to stop your medication.

Does Wegovy or Mounjaro Actually Cause Hair Loss?

Yes and no. The medications themselves don't directly damage hair follicles. What causes the shedding is the rapid weight loss they trigger — specifically a condition called telogen effluvium.

Here's what happens: when your body goes through significant physical stress — like losing weight quickly — a large number of hair follicles shift from the growth phase into the resting phase at the same time. Around 2 to 4 months later, those follicles shed their hair simultaneously, causing noticeable thinning.

It's the same process that happens after surgery, illness, pregnancy, or crash dieting. The GLP-1 medications are just very effective at causing rapid weight loss — which is why some people experience this.

The stats:

• Around 3% of Wegovy users reported hair loss in clinical trials vs 1% on placebo
• Around 4–6% of Mounjaro users reported hair loss in trials
• The higher your weight loss, the higher your risk

When Does It Start and How Long Does It Last?

Hair loss typically starts 2 to 4 months after the trigger — so you may not notice it until you've been on the medication for several months.

It usually resolves on its own within 3 to 6 months, and hair regrows fully for most people. The shedding tends to slow as your weight loss stabilises.

Why Is It Worse for Some People?

Nutritional deficiencies are the biggest factor. When you're eating much less than usual, it's easy to miss key nutrients:

• Protein — hair is made of protein (keratin). Aim for at least 80–100g per day
• Iron — especially common in women
• B12 — especially if you're also taking metformin
• Vitamin D — most UK adults are already low
• Zinc — involved in hair tissue growth and repair
• Biotin — supports keratin production

How to Prevent and Treat Hair Loss on GLP-1s

1. Hit Your Protein Target Every Day

Aim for at least 100g of protein per day. Protein shakes are brilliant when appetite is suppressed.

→ Best protein powders for GLP-1 users UK

2. Take the Right Supplements

B12 methylcobalamin — best absorbed form, especially important if also taking metformin

👉 BetterYou Vitamin B12 Spray on Amazon

Vitamin D3 — most UK adults are deficient, year-round supplementation recommended

👉 BetterYou Vitamin D3 3000IU Spray on Amazon

Iron — get levels checked first, especially if you're a woman

Biotin — specifically supports hair, skin and nails

Omega-3 — supports scalp health and reduces inflammation

→ Full supplement guide for GLP-1 users

3. Be Gentle With Your Hair

• Avoid heat styling where possible
• Use a wide-tooth comb
• Switch to a gentle sulphate-free shampoo
• Try scalp massage when washing

4. Don't Crash Your Calories

Even if you're not hungry, eat enough to meet protein and nutrient needs. A 500–800 calorie diet with no protein focus is the fast track to hair loss.

5. Get Blood Tests Done

Ask your GP for ferritin, B12, Vitamin D, zinc and thyroid function. Many deficiencies are silent until they cause symptoms.

Should You Stop Medication Because of Hair Loss?

In most cases, no. The hair loss is almost always temporary. Most people find it peaks around months 3 to 6 then naturally improves as weight loss stabilises.

Speak to your GP if:

• Hair loss is severe or continues beyond 6 months
• You're losing eyebrows or body hair too
• It started immediately when you began medication (could indicate another cause)

Quick Summary

• Hair loss is caused by rapid weight loss, not the medication itself
• It's called telogen effluvium — temporary shedding triggered by physical stress
• Starts 2 to 4 months after beginning treatment, resolves within 3 to 6 months
• Most important actions: 100g protein daily, B12, Vitamin D3, iron and biotin supplements
• Hair fully regrows for most people once weight loss stabilises
• Don't stop medication without speaking to your prescriber first

This article is for informational purposes only and does not constitute medical advice. Always consult a UK-registered healthcare professional before making changes to your medication or supplement routine.

glp1guide.live may earn a small commission if you purchase through links on this page, at no extra cost to you.