Short answer

Yes, some people notice more hair fall while on GLP-1 medicines such as semaglutide or tirzepatide, and a 2026 analysis of trials found it was reported more often than with placebo, in a small minority of users. Most of it appears to be a temporary shedding linked to rapid weight loss and eating less, which usually recovers over months. Low protein, iron, vitamin B12 or thyroid problems can add to it, so these are worth checking with your doctor.

Hair fall is one of the more upsetting things people notice a few months after starting a weight-loss injection. It is a real effect, but it is usually temporary and it is rarely a reason, by itself, to give up a treatment that is helping your health.

How common is it?

A 2026 review that pooled results from clinical studies found that hair loss was reported about three times more often in people on GLP-1 medicines than on placebo. Even so, it affected only a small minority, roughly 4 in 100 users in that analysis.

Why does it happen?

The most likely explanation is telogen effluvium. When the body goes through a stress, such as rapid weight loss, a sudden drop in food intake, illness or surgery, many hairs switch into a resting phase at once. Two to four months later, they fall together. This is the same type of shedding seen after crash dieting, dengue or childbirth. Whether the medicines also act directly on hair follicles is not known.

Other factors can add to it:

too little protein when appetite is low
low iron, vitamin B12, vitamin D or zinc
a thyroid problem. Read hair loss and the thyroid.
PCOS or genetic pattern hair loss, which can show up at the same time

Does the hair grow back?

In most cases, yes. Telogen effluvium usually settles once weight becomes stable, and new hair grows over the following months. Hair grows slowly, so full recovery can take six months or more.

What helps?

Eat enough protein at every meal, even when you are not hungry. Read protein and muscle on weight-loss medicines.
Ask your doctor whether to check ferritin, vitamin B12, vitamin D and thyroid tests.
Tell your doctor if you are losing weight very quickly. They may slow the pace.
Be careful with “hair vitamins” containing biotin, which can upset thyroid and other blood tests.

Please do not stop your medicine on your own because of hair fall. Discuss it with your doctor, who can weigh it against the benefits. For other side effects, read GLP-1 side effects and how doctors manage them.

When to see an endocrinologist

Patchy bald spots, or loss of eyebrows or eyelashes
Hair fall with tiredness, breathlessness or very heavy periods
Hair fall with weight loss much faster than your doctor expected, or very low food intake

Chest pain, fainting, severe breathlessness or confusion: call 108 or 112, or go to the nearest emergency department.

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This page is general health information and does not replace a consultation with your own doctor. Please read our medical disclaimer.

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