Why do women lose hair, and how much is too much?

When women lose more hair than usual, the cause is most often something hard on the body or mind, such as a lot of stress, giving birth, rapid weight loss, a high fever or illness, or hairstyles that pull. Most of the time it is temporary, and hair tends to return to its normal fullness once the trigger has passed. Losing 50 to 100 hairs a day is normal anyway. If hair falls out in patches, your scalp itches or hurts, or things do not improve with time, see a doctor.

How many hairs a day is too many?

The UK's NHS and the American Academy of Dermatology (AAD) agree that losing 50 to 100 hairs a day is normal, and most of the time we do not even notice. Each hair has its own cycle of growing and falling out, so seeing some hair on your brush or in the bathroom every day is not a warning sign.

What shedding more than normal looks like

• Clearly more hair than usual on your pillow, brush or drain for several days in a row
• Hair coming out in handfuls when you wash, comb or run your fingers through it
• Hair that looks thinner overall, or a ponytail that feels smaller around

Shedding is not the same as hair that stops growing

The AAD separates the two. The first is excessive shedding, which usually follows something hard on the body and stops on its own as the body readjusts. The second is hair that stops growing because something is getting in the way, such as family history, some medicines, hairstyles that pull or harsh hair products. In that case, hair will not grow back until the cause stops. Some people have both, and a dermatologist can tell which one you have.

What causes hair loss in women?

The NHS says temporary hair loss can be caused by illness, stress and weight loss. The AAD and MedlinePlus, from the US National Library of Medicine, give more detail.

Events that are hard on the body or mind

According to the AAD, excessive shedding is common in people who have recently:

• been under a lot of stress, such as caring for a sick loved one, going through a divorce or losing a job
• given birth
• lost 20 pounds (about 9 kg) or more
• had a high fever, or are recovering from an illness, especially one with a high fever
• had an operation

MedlinePlus notes that physical or emotional stress may cause one half to three quarters of scalp hair to shed, and that you may not notice it until weeks to months after the stressful episode.

Crash dieting or rapid weight loss

MedlinePlus lists crash diets among the causes. If your hair starts shedding heavily after a period of strict dieting, a large drop in weight over a short time is worth considering.

How you style and treat your hair

The AAD says that wearing tight styles often, such as tight ponytails, buns or updos, hair extensions or weaves, and rollers worn to bed most nights, keeps pulling on the hair and can lead to hair loss. The hairline is often the first place it shows. Rough washing and frequent heat or chemical treatments also make hair fragile and more likely to break.

Gradual thinning with age and family history

The NHS notes that some types of hair loss are permanent and tend to run in families. The AAD says a widening part or thinning hair is the first sign many women notice. MedlinePlus adds that some women aged 30 to 60 notice thinning across the whole scalp with no known cause. It may be heavier at first and then gradually slow or stop.

Some medicines

Some medicines can affect hair shedding. If you take a regular medicine and think it may be linked to your hair loss, talk to your doctor or pharmacist. The AAD warns against stopping on your own, because stopping a medicine suddenly can cause serious side effects.

My hair is falling out from stress. When will it stop?

Hair shed because of stress does not fall out straight away. The AAD says most people notice heavy shedding a few months after the stressful event, which is why many people do not connect the two.

How long it takes

• AAD: as the body readjusts, the heavy shedding stops, and hair tends to regain its normal fullness within 6 to 9 months.
• MedlinePlus: shedding decreases over 6 to 8 months and is usually temporary.

If the stress is still there

The AAD notes that if the stress stays with you, shedding can go on for a long time. So the focus is on the source of the stress more than on the hair itself. The self-care section below includes tips from the NHS.

I'm losing so much hair after giving birth. How long will it last, and what can I do?

Heavy shedding after childbirth is something many new mothers go through. The AAD says it is normal, is not true hair loss, and is caused by falling estrogen levels after the birth.

When it starts and when it settles

The AAD says this shedding stops on its own without you needing to do anything.

While you wait: making hair look fuller

The AAD suggests a few things to help hair look fuller until it recovers:

• Use a volumising shampoo, and avoid shampoos labelled "conditioning shampoo", which can weigh hair down and make it look limp.
• Use a conditioner made for fine hair and apply it mainly to the ends. Avoid "intensive" conditioners.
• Try a new hairstyle. A shorter cut can make hair look fuller and is easier to manage, and an experienced stylist can suggest what will suit you.

The AAD adds that finding the right shampoo and conditioner for thin hair is a matter of trial and error, and no single ingredient is clearly better than the rest.

What can I do myself about hair loss?

What you can do is cut down on things that break or pull your hair, and keep your daily routine steady. The tips below come from the AAD, the NHS and the WHO.

Washing and drying

• Gently massage shampoo into your scalp, and let it rinse through the length of your hair rather than rubbing it into the ends.
• Use conditioner after every wash.
• Wrap your hair in a towel to soak up water instead of rubbing it, and let it air dry when you can.
• Straight hair: let it dry a little, then comb gently with a wide-tooth comb. Textured or tightly curled hair: comb while damp with a wide-tooth comb.
• Brush and comb only to style. Brushing 100 strokes a day is a myth.

Heat and chemicals

• Use your hair dryer on the lowest heat setting, and use hot combs or curling irons less often, aiming for once a week or less.
• Leave more time between colour touch-ups, at least 8 to 10 weeks when the air is dry.
• Have one service at a time. If you want a perm or relaxer as well as colour, do the perm or relaxer two weeks before colouring.

Hairstyles that do not pull

• Avoid wearing tight styles often. When you tie your hair back, keep it loose and use covered hair bands.
• Switch styles now and then so your hair gets a break from tight ones.
• Wear braids for no longer than 6 to 8 weeks, and hair extensions for two or three months at most.
• If you cover your hair, pull it back loosely underneath, and choose silk or satin, which are gentler than other fabrics.
• The AAD says that if a hairstyle hurts, it is too tight, so change it straight away.

Everyday eating: a general guide

Avoid crash dieting even when watching your weight. The World Health Organization (WHO) recommends a varied diet of vegetables, fruit, whole grains, pulses and lean sources of protein. Everyone older than 10 should aim for at least 400 g of fruit and vegetables a day.

Everyday stress

The NHS suggests several ways to manage stress, including:

• Be active. It will not make stress disappear, but it can ease the emotional intensity and help you think more clearly.
• Talk things through with friends, family or colleagues.
• Set aside some time for yourself to rest and do things you enjoy.
• Do not rely on alcohol, smoking or caffeine to cope.

When should I see a doctor about hair loss?

The NHS advises seeing a GP if you are worried about your hair loss, and getting an idea of the cause from a doctor before going to a commercial hair clinic. MedlinePlus advises contacting a health care provider if you have any of the following:

• Hair falling out in patches or in an unusual pattern
• Losing hair very quickly, or at an early age, such as in your teens or twenties
• Itching or pain where the hair is falling out
• Red, scaly or otherwise unusual skin on the scalp in that area
• Acne, more facial hair, or changes in your periods
• Bald spots in your eyebrows
• Weight gain, muscle weakness, feeling the cold more than usual, or tiring easily at the same time

Also see a dermatologist if your hair has not regained its normal fullness a year after giving birth, or if stress-related shedding is not getting better after several months. The AAD notes that some types of hair loss, such as from tight hairstyles worn over a long time, can become permanent if left alone, so seeing a doctor early helps you find the cause and know what to do next.