Clinically reviewed by Dr Muhammad Najam-Ul-Arfeen, General Practitioner
Bachelor of Medicine and Bachelor of Surgery (MBBS)
AHPRA-registered
Last updated: 18 September 2026
Hair loss in women can have several causes. The causes of female hair loss range from temporary shedding after illness, childbirth, stress or weight loss to female pattern hair loss, nutritional deficiencies, hormonal conditions and scalp disorders.
The pattern and timing of hair loss can provide important clues about the underlying cause. Some women experience increased shedding across the whole scalp, while others develop gradual thinning around the part or crown, defined bald patches, or hair loss around the hairline. Identifying the pattern can help a doctor determine the likely cause and whether further testing or treatment is needed.
How to Tell What May Be Causing Your Hair Loss
| Pattern | Possible Cause |
|---|---|
| Sudden, diffuse shedding | Telogen effluvium |
| Gradually widening part | Female pattern hair loss |
| Round or defined bald patches | Alopecia areata |
| Hairline/temple thinning from tight hairstyles | Traction alopecia |
| Hair loss with scalp scaling/itching | Scalp condition |
| Hair loss with irregular periods/acne/excess facial hair | Possible androgen excess/PCOS |
Understanding the Different Causes of Hair Loss
A normal scalp holds around 100,000 hairs, with roughly 90 percent in the active growth (anagen) phase and about 8 to 10 percent resting (telogen) at any given time. Losing around 100 hairs a day is considered normal shedding.
What causes hair loss in women usually comes down to one of a few underlying mechanisms: a temporary disruption to the hair-growth cycle (telogen effluvium), gradual follicle miniaturisation (female pattern hair loss), an autoimmune reaction (alopecia areata), a scalp condition, a hormonal change, certain medicines, or physical damage to the hair itself.
Knowing which one you are dealing with changes everything downstream.
Telogen Effluvium: The Most Common Cause of Sudden Hair Shedding
Telogen effluvium is one possible explanation when hair shedding is diffuse and begins a few months after an illness, childbirth, major stressor, or other physical change. A physical or emotional shock can force an unusually large share of follicles to shift prematurely from the growth (anagen) phase into the resting (telogen) phase.
Those resting hairs are not shed immediately. Hair shedding usually becomes noticeable 2 to 4 months after the triggering event, which is why the connection between the original trigger and the hair loss can be easy to miss. You may be shedding hair now because of something that happened several months ago, not something happening today.
Common triggers include:
- Childbirth (postpartum telogen effluvium, typically peaking around 2 to 4 months after delivery)
- A high fever, surgery, or significant illness
- Rapid weight loss or a crash diet
- A major emotional stressor or loss
- Starting, stopping, or switching a hormonal medication, including the oral contraceptive pill
- Severe iron deficiency
The reassuring part is that telogen effluvium is non-scarring and does not permanently destroy the hair follicle. Once the underlying trigger resolves, shedding usually gradually settles, and normal hair growth can resume. Acute telogen effluvium commonly improves over several months, although the timeline varies between people.
Female Pattern Hair Loss (Androgenetic Alopecia): The Cause Most Women Miss
Female pattern hair loss, also called androgenetic alopecia, is often confused with telogen effluvium because both cause diffuse thinning rather than bald patches — but where telogen effluvium is temporary, female pattern hair loss is a progressive condition in which follicles gradually produce finer, shorter hairs. Genetics play a key role, and the link to androgen hormones is more complex than in male pattern baldness: most affected women have normal androgen levels, though androgen excess can contribute in some, including those with PCOS.
The pattern is distinctive — widening of the centre part, thinning concentrated at the crown and frontal scalp, with the hairline usually intact — and is graded clinically using the Ludwig scale, which describes three stages of increasing central thinning.
Because it tends to progress without treatment, early assessment by a GP or dermatologist matters. Topical minoxidil is the main evidence-based treatment, helping slow hair loss and promote some regrowth, though results vary and benefits take several months and ongoing use to maintain.
PCOS Hair Loss: When Hormonal Symptoms May Provide a Clue
PCOS can be associated with female pattern hair loss, particularly when androgen levels are elevated. However, hair thinning alone does not mean you have PCOS.
If hair loss occurs alongside irregular or absent periods, acne or increased facial or body hair, it is worth discussing these symptoms with a GP. Depending on your symptoms and examination, your doctor may consider hormone testing to look for androgen excess and assess whether PCOS or another hormonal condition could be contributing.
f you’re noticing hair thinning alongside irregular periods or other hormonal symptoms, you can [speak with a GP about PCOS or hormonal symptoms] through HelloGP.
Female Hair Loss During Menopause: Why Hair Thinning Can Increase
Menopause hair loss is extremely common and is driven by a genuine hormonal shift, not simply ageing in the abstract. Oestrogen and progesterone both support the hair growth phase, and as their levels drop during perimenopause and menopause, the relative influence of androgens increases even without any absolute rise in androgen levels.
Female pattern hair loss also becomes more common after menopause, although the exact role of oestrogen in the condition is not fully understood.
For some women, menopause may coincide with the first noticeable signs of female pattern hair loss. Other causes of shedding can also occur during this stage of life, so persistent or progressive thinning should not automatically be attributed to menopause alone.
Nutrient Deficiencies: The Cause With an Actual Number Attached
Iron deficiency can cause diffuse hair shedding, especially when other symptoms or medical history suggest low iron stores. Vitamin D deficiency and hair loss show a similar pattern in the research: women with diffuse hair loss have been found to have significantly lower average vitamin D levels than women without hair loss.
Some studies have found an association between low vitamin D levels and certain types of hair loss. However, this does not mean that vitamin D deficiency is the cause of hair loss in every woman, and supplementation is not appropriate unless a deficiency or increased risk of deficiency has been identified.
Other nutrient-related contributors worth knowing:
- Zinc deficiency, which plays a role in follicle protein synthesis and repair
- Inadequate protein or overall calorie intake, from very low-calorie or low-protein diets, since hair is structurally almost entirely keratin, a protein
- Vitamin B12 and folate deficiency, more common in vegetarian and vegan diets without adequate supplementation
Thyroid dysfunction — whether an underactive or overactive thyroid — is a separate but common trigger for telogen effluvium, and is usually reversible once thyroid levels are corrected with treatment.
If you have persistent or unexplained diffuse hair shedding, discuss it with your GP. Depending on your symptoms, diet, menstrual history, medical history and examination, your GP may consider blood tests such as iron studies, thyroid function or other tests to investigate possible causes.
Stress Related Hair Loss in Women: More Physiological Than People Assume
Stress-related hair loss in women is not purely psychological, it works through the same telogen effluvium mechanism described above. Because of the 2–4 month delay, the stressor may have occurred well before the shedding became noticeable. Other triggers, including illness, childbirth, rapid weight loss and some medicines, can cause the same type of delayed shedding.
Other Causes of Hair Loss
Traction Alopecia
Traction alopecia, from prolonged tension on the hair shaft caused by tight ponytails, braids, or extensions, which causes thinning concentrated specifically along the hairline and temples rather than diffusely
Alopecia Areata
Alopecia areata, an autoimmune condition causing well-defined, often coin-sized patches of hair loss rather than diffuse thinning, distinct from every cause described above
Certain Medications
Certain medications, including some blood pressure medications, anticoagulants, and retinoids, which can trigger a drug-induced telogen effluvium
Scalp Conditions
Scalp conditions, such as seborrheic dermatitis or fungal infections, which can cause localised shedding and irritation
How Is Hair Loss in Women Diagnosed?
A GP or dermatologist will usually assess the pattern and timing of your hair loss and ask about recent illness, childbirth, weight changes, stress, diet, medicines and other health conditions. Examining the scalp and hair can help distinguish diffuse shedding from patterned, patchy or scalp-related hair loss.
Blood tests are not necessary for everyone with hair loss. Depending on your symptoms, medical history and examination, your doctor may consider a full blood count, iron studies (including ferritin), and thyroid function tests (TSH), and: thyroid function tests (TSH); and, if your history suggests it, hormone tests such as testosterone or DHEA-S to check for conditions like PCOS.
If the cause is unclear, a dermatologist may use trichoscopy to examine the scalp and hair more closely. In selected cases, further assessment, including a scalp biopsy, may be considered.
When to See a Doctor
Book an appointment rather than waiting it out if any of the following apply:
- Shedding has continued for more than 6 months without improving
- You notice a defined bald patch rather than diffuse thinning
- Hair loss is accompanied by irregular periods, new acne, or new facial or body hair growth
- You have symptoms of thyroid dysfunction, such as fatigue, weight change, or temperature sensitivity
- Thinning is progressive and concentrated at the crown or part line, suggesting female pattern hair loss rather than a temporary shed
- You have persistent or unexplained hair shedding and want to understand whether further assessment or blood tests are needed.
- You have scalp pain, burning, significant redness, crusting or persistent scaling along with hair loss.
A GP can order the right bloodwork, rule out or confirm the mechanisms above, and refer you on for further specialist assessment if needed.
Frequently Asked Questions (FAQ)
What is a major cause of hair loss?
For women, the two most common underlying mechanisms are telogen effluvium (a temporary, trigger-driven disruption to the hair growth cycle, often from stress, illness, childbirth, or nutrient deficiency) and female pattern hair loss (androgenetic alopecia), a progressive, genetically influenced miniaturisation of the follicle. Identifying which one you have changes the entire treatment approach.
Which vitamin or nutrient deficiency causes hair loss?
Iron deficiency can be associated with diffuse hair shedding, and a doctor may consider iron studies when investigating unexplained hair loss. Some studies have also reported associations between hair loss and vitamin D, zinc, vitamin B12 or folate deficiencies. Testing and supplementation should be guided by your symptoms, diet, medical history and clinical assessment rather than assuming a deficiency is the cause.
What blood tests are done for hair loss in women?
A GP will usually start with a full blood count, iron studies (including ferritin) and thyroid function tests. Depending on your symptoms — such as irregular periods, acne or excess facial hair — hormone tests may also be considered to check for conditions like PCOS. Not everyone with hair loss needs blood tests; your GP will decide based on your history and examination.
Which hormone causes hair loss in females?
There is no single hormone responsible for all female hair loss. Female pattern hair loss has a strong genetic component, and most women with the condition have normal androgen levels. Androgen (a group that includes testosterone) excess can contribute to hair loss in some women, even at the relatively low levels normally present in women. It can drive follicle miniaturisation in genetically sensitive individuals. This mechanism underlies both female pattern hair loss and PCOS-related hair loss. Falling oestrogen during perimenopause and menopause can also unmask this androgen sensitivity.
How to stop hair from falling out?
Treatment depends on the cause. Telogen effluvium often improves once the underlying trigger has resolved, although shedding can continue for several months. Female pattern hair loss tends to progress gradually without treatment, and treatments such as topical minoxidil may help slow hair loss and promote some regrowth in some people. If hair loss is persistent or progressive, a GP or dermatologist can assess the likely cause and discuss appropriate treatment.
What is the best treatment for thinning hair?
There is no single best treatment for every type of hair loss, because thinning hair in women has several distinct causes. Topical minoxidil has the strongest evidence base for female pattern hair loss specifically. For telogen effluvium, treatment means correcting the underlying trigger (iron repletion, thyroid correction, stress management) rather than a topical product. A proper diagnosis is what determines which approach will actually work for you.
Can stress cause hair loss in women?
Yes. Significant physical or emotional stress can trigger telogen effluvium, a type of diffuse hair shedding. The shedding often becomes noticeable several months after the stressful event rather than immediately, so the timing of the hair loss may not seem connected to the original stressor.
Is postpartum hair loss normal, and how long does it last?
Postpartum shedding is a common form of telogen effluvium associated with hormonal and physiological changes after childbirth. Hair shedding often becomes noticeable around 2 to 4 months after delivery and usually gradually improves over the following months. If shedding remains heavy or does not improve, it is worth discussing it with a GP rather than assuming it is still normal postpartum shedding.
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