Hair loss in women: causes, blood tests and treatments

Losing more hair than usual is stressful, and the internet is full of oils and supplements that promise fast results. The first step is not a product. It is finding out which type of hair loss you have, because each type has a different plan.

Quick answer: Most hair loss in women is either sudden, all-over shedding a few months after a shock to the body (telogen effluvium, which usually recovers), or slow thinning on the top of the head (female pattern hair loss, which needs ongoing treatment). A doctor may check iron, thyroid and other blood tests. Topical minoxidil is the best-proven non-prescription treatment for thinning; give it 6–12 months.

How much hair loss is normal?

Most people lose about 50 to 100 hairs a day, often without noticing. You may see more on wash days, because hairs that had already come loose rinse out together. Hair loss becomes a concern when you notice clumps in the shower or on your brush, a wider parting, more scalp showing through, or bald patches.

The main types of hair loss in women

Telogen effluvium

Hair grows in cycles. A big shock to the body (a high fever, an illness, surgery, childbirth, a crash diet or severe stress) can push many hairs into the resting phase at once. About 2–3 months later, they fall out together. It can feel alarming, but the hair roots are not destroyed. Once the trigger is gone, shedding usually slows within several months, and regrowth follows.

Female pattern hair loss

This is the most common cause of thinning in women. Hair follicles slowly shrink, so thick hairs are replaced by finer, shorter ones. It usually starts with a wider center part. It tends to run in families and becomes more common after menopause. It does not stop on its own, so earlier treatment helps keep more hair.

Traction alopecia

Styles that pull hard on the roots, day after day, can damage follicles. Caught early, hair often grows back once the pulling stops. After years of tension, the loss can become permanent.

Tests your doctor may suggest

A doctor or dermatologist will look at your scalp and ask about your health, diet, periods and recent events. Depending on what they find, they may order blood tests such as:

• Ferritin and iron levels. Low iron stores are common in women with heavy periods or diets low in iron.
• Thyroid function. Both an underactive and an overactive thyroid can cause shedding.
• A full blood count, and sometimes vitamin D, vitamin B12 or folate.
• Hormone tests if you also have irregular periods, acne or extra facial or body hair, which can be signs of polycystic ovary syndrome (PCOS).

A note about biotin

Biotin is in many "hair, skin and nails" supplements. The FDA has warned that high amounts of biotin can interfere with some lab tests and give false results. Tell your doctor if you take biotin before any blood test. Biotin supplements only help hair if you are actually low in biotin, which is rare.

Treatments with evidence

Topical minoxidil

Minoxidil applied to the scalp is FDA-approved for female pattern hair loss and is sold without a prescription as a liquid or foam. It helps keep hairs in their growing phase longer. It works best for early thinning and will not regrow a full head of hair.

What to expect:

• A temporary increase in shedding in the first 2–8 weeks is common and usually stops as new growth starts.
• You need to use it for about 6–12 months before judging whether it works.
• You must keep using it to keep the results. If you stop, the extra hair is gradually lost.
• The most common side effect is an itchy, flaky scalp. Unwanted facial hair can happen if it runs onto the face.
• Do not use it if you are pregnant, planning a pregnancy or breastfeeding.

Follow the label or your doctor's advice on which strength to use and how often.

Prescription options

A dermatologist may suggest prescription medicines, sometimes together with minoxidil:

• Anti-androgen tablets, such as spironolactone, which reduce the effect of male-type hormones on hair follicles.
• Low-dose oral minoxidil, a tablet some dermatologists prescribe when the topical form is not suitable. It needs medical follow-up.
• Other hormone-blocking medicines in selected cases.

Many of these must not be used in pregnancy, and women who could become pregnant are usually advised to use birth control while taking them. Talk to your doctor about the benefits and side effects for you.

Fixing what is underneath

If your blood tests show low iron or a thyroid problem, treating it can stop the shedding. Do not start iron tablets without a test, because too much iron can be harmful.

Devices and procedures

• Laser caps, combs and helmets (low-level red light): some are FDA-cleared for home use. A few studies show modest benefit; long-term safety is not fully known.
• Platelet-rich plasma (PRP): your own blood is processed and injected into the scalp. Early research is promising, but more study is needed.
• Hair transplant: may suit women with stable, patchy thinning, but not women whose hair is thin all over.

What about oils and supplements?

Rosemary oil is the most talked-about oil. One small trial in men with pattern hair loss found similar results to a low-strength minoxidil after 6 months. That is interesting, but it is one study, so rosemary oil is best seen as an add-on, not a replacement. Learn more about rosemary oil.

Supplements only help if you are actually deficient. A balanced diet with enough protein and iron matters more than any "hair gummy."

What not to mix

• Minoxidil and scalp oils at the same moment. Apply minoxidil to a dry scalp, and use oils at a different time, if at all.
• Minoxidil and pregnancy or breastfeeding. Not recommended.
• Tight styles and treatment. No treatment can win against daily pulling on the roots.

Daily hair care that helps

• Wash as often as your scalp needs with a gentle shampoo, and condition the lengths.
• Detangle wet hair with a wide-tooth comb, starting from the ends.
• Keep heat styling low and use a heat protectant.
• Choose loose styles and switch them up; take breaks from extensions and weaves.
• Sleep on a satin or silk pillowcase or bonnet to reduce friction.
• Treat an itchy or flaky scalp. Look after your scalp care as much as your lengths.

For more everyday tips, see thinning hair and shedding.

How long until results?

• Telogen effluvium: shedding usually settles within several months after the cause is fixed. Full regrowth can take up to a year, because hair grows slowly.
• Minoxidil: shedding often slows after a few months; new growth tends to show from around 6 months. Judge it at 12 months, and keep going to keep the result.

When to see a doctor

• Sudden round bald patches.
• A shiny scalp, redness, scaling, pain, burning or itching where hair is lost.
• Hair loss with weight change, tiredness, feeling cold or hot, irregular periods, acne or new facial hair.
• Heavy shedding that lasts more than about 6 months.
• Hair loss after starting a new medicine.
• Any hair loss that is affecting how you feel day to day.

A dermatologist can confirm the type of hair loss, sometimes with a closer look through a magnifier or a small scalp sample, and build a plan that fits you.

FAQ

Does washing hair often cause hair loss?

No. Washing only removes hairs that were already shed. It can look like more on wash day because hairs collect between washes.

Is hair loss after giving birth normal?

Yes. Many women shed more hair a few months after giving birth. It usually recovers on its own within months to a year. If it does not, see a doctor.

Will dyeing my hair make it fall out?

Dye can damage the hair shaft and cause breakage, but it does not usually affect the root. A burning, itchy or swollen scalp after dyeing can be an allergic reaction: rinse and see a doctor.

Can stress cause hair loss?

Yes. Severe stress can trigger telogen effluvium, usually a few months after the stressful event. It typically recovers once things settle.

Can women use finasteride?

Finasteride is not used in women who are or could become pregnant, because it can harm a developing baby. A dermatologist may consider hormone-blocking medicines in specific cases.

Sources

• Thinning hair and hair loss: Could it be female pattern hair loss? (American Academy of Dermatology)
• Hair loss (NHS)
• Telogen effluvium (hair shedding) (DermNet)
• Testing for Biotin Interference in In Vitro Diagnostic Devices (US Food and Drug Administration)
• Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial (PubMed, NIH)