Wegovy hair loss is a recognised side effect: the UK product information lists hair loss as common, and in the clinical studies it was reported in 2.5% of people taking semaglutide compared with 1.0% on placebo, and more often in people who lost 20% or more of their body weight. It is usually a temporary form of shedding called telogen effluvium, triggered by rapid weight loss, a sharp fall in calories or protein, or physical stress on the body. Shedding typically begins around two to three months after the trigger and settles over several months, with regrowth following. Enough protein, a balanced diet that covers iron and other nutrients, gentle hair care and patience help most. See a clinician for patchy loss, a sore scalp or loss that is not settling.
The UK Summary of Product Characteristics for Wegovy lists hair loss among its common side effects, meaning it affects between 1 in 100 and 1 in 10 people. The product information describes the figures from phase 3a clinical studies: hair loss was reported in 2.5% of patients treated with semaglutide and in 1.0% of patients who received a placebo. It also notes that hair loss was reported more frequently in people with greater weight loss, specifically 20% or more of body weight.
This is worth keeping in perspective. Most people taking Wegovy do not notice significant hair loss, and the difference between treatment and placebo in the studies was modest. But because Wegovy can produce large weight loss, and because hair loss is linked to how fast and how far weight falls, it is a well-recognised experience for a minority of people.
Percentage of people reporting hair loss in the semaglutide phase 3a studies described in the UK product information. Bars drawn to scale. Hair loss was also reported more often in people who lost 20% or more of their body weight.
Each hair follicle goes through a repeating cycle. In the growth phase (anagen), which lasts several years, the hair grows. In a short transition phase (catagen) growth slows, and in the resting phase (telogen) the hair rests for around three months before it falls out and a new one begins. At any one time, most scalp hairs, usually around 85 to 90%, are growing, and a small proportion are resting. Losing 50 to 100 hairs a day is normal.
When the body is put under stress, a larger share of follicles can be pushed into the resting phase at the same time. Around two to three months later, they all shed together. This is called telogen effluvium. It causes diffuse thinning across the scalp rather than bald patches, and it usually corrects itself once the trigger passes, because the follicles themselves are not damaged.
Why hair loss can happen on WegovyWegovy is not thought to attack hair follicles directly. The most widely accepted explanation is that the changes that come with rapid weight loss act as triggers.
- Rapid weight loss itself, which the body can register as a physical stress.
- Eating much less, so that calorie intake falls sharply.
- Low protein intake, because hair is made of the protein keratin and growth is energy-intensive.
- Shortfalls in iron, zinc, vitamin D, vitamin B12 or other nutrients when the diet becomes very restricted.
- Other stressors happening at the same time, such as illness, surgery, significant emotional stress or pregnancy.
- Hormonal changes, including those around the menopause, which can also affect hair density.
| Likely contributor | Why it matters for hair | What can help |
|---|---|---|
| Fast, large weight loss | Can trigger a wave of shedding 2 to 3 months later | Discuss pace with your prescriber; do not add crash dieting |
| Low calorie intake | Follicles need energy to grow | Regular meals; avoid very low intakes |
| Low protein | Hair is made of protein | Aim for protein at every meal |
| Low iron or ferritin | A common and treatable cause of diffuse thinning | Ask your GP about blood tests |
| Low vitamin D, B12 or zinc | Linked to hair and scalp health | Balanced diet; test before supplementing |
| Hormonal change | Menopause and thyroid changes affect hair | Discuss with your GP |
| Other illness or stress | Can trigger telogen effluvium on its own | Treat the cause; allow time |
It helps to know what to expect, because the delay between the trigger and the shedding often catches people out. You may notice shedding months after your weight loss began, even when your eating has recently stabilised.
| Stage | What you may notice | Typical timing |
|---|---|---|
| Trigger | Rapid weight loss, low intake or other stress begins | Month 0 |
| Hairs move into the resting phase | Nothing visible yet | Weeks 1 to 8 |
| Shedding begins | More hair in the shower, brush or pillow; thinner ponytail | Around 2 to 3 months after the trigger |
| Shedding peaks and settles | Gradual reduction in shedding | Over several months, often up to 6 months |
| Regrowth | Short new hairs along the hairline and parting | From around 3 to 6 months, with full density taking longer |
These timings are typical, not guaranteed. Shedding can last longer when weight loss continues for a long period, and regrowth is gradual, because hair grows only about a centimetre a month.
What helpsEat enough, and eat protein
- Aim to eat regularly even if appetite is low, because very low intakes make the problem worse.
- Include protein at each meal: eggs, fish, chicken, dairy, tofu, beans or a shake on low-appetite days. A 2025 US joint advisory on nutrition during GLP-1 treatment suggests 1.2 to 1.6 grams of protein per kilogram per day during active weight loss, with a practical target of about 80 to 120 grams a day. This is US guidance, but the principle applies.
- Include iron-rich foods such as lean red meat, pulses and leafy greens, and vitamin C foods alongside plant iron to help absorption.
- Include foods with zinc, such as meat, shellfish, dairy, nuts and seeds, and sources of vitamin B12 such as meat, fish, eggs and dairy, particularly if your diet is mostly plant-based.
Be careful with supplements
- A multivitamin may be considered if you are eating very little, but ask your pharmacist or GP first.
- Do not take high doses of single supplements without a reason. Too much of some, such as vitamin A and selenium, can itself cause hair loss.
- Biotin supplements are popular, but they help hair only in the rare case of a true deficiency, and high doses can interfere with some blood tests, including thyroid tests. Tell any clinician who orders blood tests if you take it.
Be gentle with your hair
- Avoid tight hairstyles, harsh chemical treatments and very hot styling tools while you are shedding.
- Use a soft brush and avoid brushing wet hair roughly.
- Gentle shampoos are fine. Shampoo does not cause the shedding, and washing does not make it worse; the hairs were already due to fall.
Consider pace and dose
If shedding is distressing, your prescriber may discuss whether your dose, pace of weight loss or eating pattern needs adjusting. Do not skip or change doses on your own. Staying longer on a lower dose before stepping up can be a reasonable choice in some cases.
Be patient and keep perspective
Because the shedding is delayed, nothing you do today changes hair that is already due to fall. What you eat and how you look after yourself now supports the hairs that come through over the coming months. Many people find tracking progress with a monthly photo in the same light more reassuring than checking the brush.
- Cutting calories further in the hope of staying slim while regrowing hair.
- Expensive hair-loss shampoos or serums with no evidence behind them.
- Stopping Wegovy suddenly purely because of shedding, without discussing it first. Stopping brings its own consequences for weight and health, and hair loss can also happen after stopping, as the weight changes.
Not all hair loss on Wegovy is caused by Wegovy, and some causes need separate treatment. A pharmacist, GP or dermatologist can help tell them apart.
| Type | Typical pattern | What to do |
|---|---|---|
| Telogen effluvium | Diffuse shedding all over the scalp, 2 to 3 months after a trigger | Allow time, correct nutrition |
| Iron deficiency | Diffuse thinning, tiredness, pallor | Ask your GP for blood tests |
| Thyroid problems | Thinning with tiredness, weight or mood changes | Ask your GP for thyroid tests |
| Female or male pattern hair loss | Gradual thinning at the crown or parting, or receding hairline | See your pharmacist or GP about options |
| Alopecia areata | Round, smooth bald patches | See your GP or a dermatologist |
| Scalp conditions | Itch, flaking, redness, tenderness | See your GP or pharmacist |
Hair shedding during weight loss is not specific to one medicine. If you take or are considering Mounjaro, our guide to hair loss on Mounjaro covers the same topic for tirzepatide.
When to get adviceSPEAK TO A CLINICIAN
Seek advice if hair loss is patchy or leaves bald areas, comes with a sore, red, scaly or scarred scalp, is accompanied by tiredness, a pale complexion, cold intolerance or other new symptoms, has not started to settle after six months, or is affecting your wellbeing. Ask for blood tests to check for iron, thyroid and vitamin deficiencies if shedding is heavy or prolonged.
Hair is closely tied to identity, and thinning can be distressing, even when it is temporary. If you feel low, anxious or are avoiding social situations, tell your GP or prescriber. Support is available, and emotional wellbeing is part of safe weight management.
Questions to ask your pharmacist or prescriber- Could my dose or pace of weight loss be contributing?
- Should I have blood tests for iron, ferritin, thyroid, vitamin D or B12?
- Is my protein and calorie intake adequate?
- Are any supplements appropriate for me?
- How long should I wait before I worry?
The bottom line
Hair loss on Wegovy is a recognised, common side effect, but it is usually a temporary shedding triggered by rapid weight loss rather than by the medicine damaging the follicles. It tends to start two to three months after the trigger and settles over several months, with regrowth following. Eat regularly, include protein at every meal, cover iron and other nutrients, treat your hair gently and give it time. Speak to a clinician if loss is patchy, comes with a sore scalp or other symptoms, or has not begun to settle after about six months.
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Start Your Free Online Consultation Use code SWITCH10 if you're switching from another provider Happy Pharmacy is a GPhC-registered pharmacy (No. 9013192). Superintendent Pharmacist: Palvinder Deol. Rated 4.8★ Excellent on TrustpilotMedical disclaimer. This guide is for general information and is not a substitute for personal medical advice. Weight-loss medicines are prescription-only and are not suitable for everyone. Always follow the patient information leaflet and the advice of your prescriber or pharmacist.
- Wegovy (semaglutide) solution for injection in pre-filled pen: UK Summary of Product Characteristics, sections 4.4, 4.8 and 5.1. electronic Medicines Compendium (emc).
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
- Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society. 2025.
- British Association of Dermatologists. Patient information leaflet: Telogen effluvium.
- NHS. Hair loss: causes and treatment.