Does weight loss cause hair loss?

Does weight loss cause hair loss?

Yes, it can. The NHS lists weight loss as a cause of hair loss that may be temporary.

Skin doctors call it telogen effluvium. More hair than usual falls out from all over the scalp. The British Association of Dermatologists lists marked weight loss and extreme dieting as common triggers.

You’d usually see thinner hair overall, not bald patches. It shows most after washing or brushing.

Some loss is normal. The NHS says we lose between 50 and 100 hairs a day, often without noticing.

Note the month your weight loss started or sped up. It helps you and your GP spot the trigger.

Does Wegovy or Mounjaro cause hair loss?

It can. The NHS lists hair loss as a common side effect of semaglutide (Wegovy) and tirzepatide (Mounjaro).

For both, it was mainly mild. Most people recovered while they kept taking the medicine.

On Wegovy, hair loss was reported more often in people who lost 20% or more of their weight.

Bothered by it? The NHS says to speak to a pharmacist or doctor, and keep taking your medicine unless you’re advised to stop. Never stop or change a prescribed medicine without your prescriber.

On a jab? See Wegovy blood tests and Mounjaro blood tests.

Why does hair fall out months after I lost weight?

Each hair grows, rests, then falls out. At any time, about 85% of scalp hairs are growing and about 15% are resting.

A resting hair waits two to four months. Then a new hair pushes it out. After a trigger, the resting share can jump to 30% or more.

That 3-month gap is the clue. Shedding can start around 3 months after a trigger. So hair falling out now may link back to weight you lost months ago.

Count back 3 months from when shedding began. Other triggers include severe illness, childbirth, surgery, major life stress and starting a new medicine. For 1 in 3 people, no cause is found.

Will my hair grow back?

Usually, yes. Telogen effluvium usually gets completely better without treatment. Shedding lasts 3 to 6 months, then new hair starts to grow.

Full thickness can take many months to return. Taking medicine does not speed up regrowth.

Two things to watch. Shedding can come back if a cause such as iron deficiency isn’t treated. And it’s called chronic (long-term) if it lasts more than 6 months.

Sometimes shedding is how people first find out they have pattern hair loss. The NHS says that type is permanent and usually runs in families. See treatments for women and for men.

While you wait, a volumising shampoo or hair fibre powder can help hide thinning.

How can I protect my hair while losing weight?

Vegan, vegetarian or on another restricted diet? Skin doctors say to consider a supplement. On semaglutide, the NHS says you’ll need a healthy, balanced diet.

For meal ideas, see protein for weight loss. On a jab, see which nutrients to check.

Hair loss can also be a less common sign of iron deficiency anaemia. Common signs are tiredness and lack of energy, shortness of breath, noticeable heartbeats, paler skin than usual and headaches.

Your doctor may do a blood test to rule out thyroid problems and iron deficiency. See the telogen effluvium blood test and ferritin test.

When to speak to a GP

A GP may be able to tell the cause by looking at your hair. Book an appointment if:

• You’re worried about your hair loss. The NHS says to see a GP before a commercial hair clinic.
• Shedding isn’t getting better. Skin doctors advise seeing your doctor.
• You think you might have iron deficiency anaemia, such as feeling tired and short of breath.
• A jab side effect bothers you or doesn’t go away. A pharmacist can help too.

Call 111 if you’re on semaglutide or tirzepatide and think you might be having serious side effects. These include severe stomach or back pain that doesn’t go away, severe tummy pain, a swollen throat or tongue, or a raised itchy rash. Others are difficulty breathing, sweating, shaking or dizziness, or changes in your sight.

See also blood tests for hair loss.