Skin · · 8 min read

Hair loss: causes, treatment and when to see a doctor

Losing up to 100 hairs a day is normal, because each hair grows for years, falls out and is replaced. It is worth a visit when shedding increases, your part widens, you notice bald patches or the scalp burns or itches. The cause decides the treatment, and fixing the cause, such as an iron or thyroid problem, is sometimes enough to let the hair grow back.

Illustration of a head seen from above with brown hair parted in the center, next to a teal comb and two loose hairs

In short

  • Shedding up to 100 hairs a day is normal, and in most people those hairs grow back.
  • Shedding that starts a few months after a stressful event, illness or hormonal change is usually temporary.
  • Pattern baldness, the most common type, is hereditary and affects both men and women.
  • Blood tests, such as thyroid and iron levels, help look for treatable causes.
  • Treatments work only while you keep using them, so give any method time and ask a clinician first.

How hair grows and what is normal

MedlinePlus says most hairs grow for up to six years and then fall out, and new hairs replace them. The average person has about 5 million hairs and loses up to 100 from the scalp each day, which is usually not noticeable.

Hair loss becomes a concern when shedding increases and fewer or no strands grow back. Photos taken a few months apart can show the change more objectively than counting hairs in the brush.

The main types

  • Androgenic alopecia (pattern baldness): hereditary thinning, the most common type, in men and women.
  • Telogen effluvium: rapid shedding that typically begins a few months after physical or emotional stress, or after sudden hormonal changes.
  • Alopecia areata: an autoimmune condition in which the immune system attacks hair follicles, usually causing small round patches with no rash or scarring.
  • Anagen effluvium: very rapid loss caused by treatments such as chemotherapy.
  • Scarring alopecia, which a dermatologist assesses.

Tight hairstyles can also cause hair loss, which is one reason to look at your habits as well as your health.

Common causes

  • Genetics and family history.
  • Stress, illness or surgery, with shedding that starts a few months later.
  • Hormonal changes such as pregnancy, childbirth and menopause.
  • Thyroid disease, and diseases such as diabetes or lupus.
  • Iron or protein shortfalls, a low-protein diet or sudden weight loss.
  • Some medicines and cancer treatments.
  • Tight hairstyles, chemical processing and scalp fungal infections.

The NHS says hair loss from a medical condition usually stops or regrows once the person recovers.

What you can do

  1. Look at the timeline.Note any illness, surgery, childbirth, diet change or new medicine in the 3 to 4 months before shedding began.
  2. Eat enough.Cleveland Clinic suggests a diet with enough calories, protein and iron.
  3. Go easy on your hair.Avoid tight hairstyles and rough chemical processing.
  4. Manage stress and treat other conditions.Treating thyroid or other conditions can help the hair.
  5. See a clinician before a hair clinic.The NHS advises seeing a GP before considering a commercial hair clinic.

When to see a doctor, and red flags

See a primary care provider or a dermatologist if you are worried about your hair loss, if shedding stays high, if you lose hair on the body as well as the scalp, or if you lose a lot of hair suddenly. Cleveland Clinic also lists burning, itching or irritation of the scalp.

Alopecia areata raises the risk of thyroid disease, eczema and other autoimmune diseases, so NIAMS advises regular visits with your primary care provider. If hair loss brings stress, depression or anxiety, a mental health professional can help.

How a clinician works out the cause

A provider reviews your family and medical history and looks at your hair and scalp. For alopecia areata, doctors usually examine the bald areas and your nails, and may use a handheld magnifier to look at hair and follicle openings.

Blood tests for thyroid function and iron levels may be ordered, and a scalp biopsy can rule out other conditions that cause similar hair loss. A scalp check for infection is also possible.

Treatment options in general terms

  • Treating the cause, such as a medicine, a hormone problem, thyroid disease or diet, is often enough.
  • Topical minoxidil, available over the counter, is usually the first option for thinning hair. Women can use minoxidil but should not use finasteride.
  • Oral finasteride is prescription-only and approved only for men with male pattern baldness.
  • These treatments do not work for everyone, and they only work while you keep using them.
  • For patchy alopecia areata, corticosteroid injections are often used, and JAK inhibitors are approved for adults with severe disease.
  • Hair transplants and platelet-rich plasma (PRP) injections are other options, and wigs or hairpieces are a choice some people prefer.

Most hair loss needs no treatment at all. Many people with alopecia areata regrow hair without it, although the course is unpredictable and the hair does not always come back.

Living with hair loss

Hair loss can be upsetting, and NIAMS notes that stress, depression and anxiety are more common in people with alopecia areata. The NHS says a clinician can arrange counseling, and that support groups or online forums can help.

If you have lost scalp hair, protect bare skin with sunscreen and use hats or scarves against sun and cold. If you have lost eyebrows or eyelashes, glasses or sunglasses protect your eyes. Wigs, bandanas, makeup and other cosmetic options are a personal choice, and some wigs are available through health services, though you may have to pay.

Questions and answers

Can iron deficiency cause hair loss?

Yes. The NHS lists iron deficiency among temporary causes, and Cleveland Clinic points to gaps in iron and protein. A clinician can check your levels.

Is stress-related shedding permanent?

Usually not. It tends to start a few months after the stressful event and settles as you recover.

Can women use minoxidil?

Yes, but not finasteride, according to the NHS. Ask your clinician first, especially if you are pregnant or planning a pregnancy.

Will alopecia areata grow back?

It varies. Some people regrow fully and others do not. Less extensive loss, later onset, no nail changes and no family history make regrowth more likely.

Does hair loss mean I am sick?

Often not, since pattern baldness is hereditary. But thyroid disease and other conditions can play a part, which is why a short checkup is worthwhile.

Sources

  1. NHS — Hair loss
  2. NIAMS — Alopecia Areata
  3. NIAMS — Alopecia Areata: Diagnosis, Treatment, and Steps to Take
  4. MedlinePlus — Hair Loss
  5. Cleveland Clinic — Hair Loss

Sources checked on 29 October 2026.

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