Causes of hair loss range from common hereditary conditions to underlying medical disorders, medications, and lifestyle factors. In the UK, hair loss affects millions of people across all ages and genders, yet the root cause is frequently misunderstood or left uninvestigated. Whether you are noticing gradual thinning, sudden patchy loss, or diffuse shedding, understanding why hair loss occurs is the essential first step towards effective management. This article outlines the most clinically recognised causes, associated medical conditions, drug-related triggers, and the NHS diagnostic and treatment pathways available to help you seek the right support.
Summary: Causes of hair loss include hereditary androgenetic alopecia, telogen effluvium triggered by stress or illness, autoimmune conditions such as alopecia areata, thyroid disorders, iron deficiency, and certain medications.
- Androgenetic alopecia is the most common cause, driven by DHT sensitivity, affecting around 50% of men by age 50 and up to 40% of women by age 70.
- Telogen effluvium is a temporary diffuse shedding triggered by physiological stressors such as childbirth, severe illness, or nutritional deficiency, usually resolving within 6–12 months.
- Medical causes include thyroid disorders, iron deficiency, PCOS, and autoimmune conditions; scarring alopecias require urgent dermatology referral to prevent permanent follicle loss.
- Medications including anticoagulants, beta-blockers, retinoids, and chemotherapy agents are recognised causes; patients should not stop prescribed medicines without consulting their clinician.
- NHS investigations are guided by clinical findings and include FBC, serum ferritin, and thyroid function tests as baseline; hormone profiles and scalp biopsy are reserved for specific indications.
- Treatment depends on the underlying cause; options include topical minoxidil, prescription finasteride for men, corticosteroids for alopecia areata, and MHRA-approved baricitinib for severe cases.
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Common Causes of Hair Loss in the UK
Androgenetic alopecia is the most common cause of hair loss in the UK, affecting around 50% of men by age 50; telogen effluvium, alopecia areata, and traction alopecia are also frequently encountered.
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Hair loss is a widespread concern in the UK, affecting both men and women at various stages of life. The most common form is androgenetic alopecia, often referred to as male-pattern or female-pattern baldness. This hereditary condition is driven by sensitivity to dihydrotestosterone (DHT), a derivative of testosterone, which causes hair follicles to shrink progressively over time. It is estimated to affect around 50% of men by the age of 50; in women, prevalence increases notably after the menopause, with studies suggesting up to 40% of women are affected by the age of 70. Importantly, female pattern hair loss can occur even when androgen levels are within the normal range.
Another frequently encountered cause is telogen effluvium, a temporary form of diffuse hair shedding that typically follows a physiological stressor. Common triggers include:
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Significant weight loss or nutritional deficiency (particularly low iron or ferritin; low vitamin D has been associated with hair shedding in some studies, though evidence for a direct causal role remains limited and testing is recommended only where risk factors exist)
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Childbirth — postpartum shedding typically peaks around three to four months after delivery and usually improves by six to twelve months
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Severe illness, surgery, or prolonged psychological stress
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Crash dieting or restrictive eating patterns
In most cases of telogen effluvium, hair regrowth occurs naturally within six to twelve months once the underlying trigger is addressed. However, persistent shedding warrants further investigation.
Alopecia areata, an autoimmune condition causing patchy hair loss, affects approximately 2% of people over their lifetime and can occur at any age. Traction alopecia — caused by prolonged tension on the hair from tight hairstyles, extensions, or chemical treatments — is an increasingly recognised and preventable cause. Trichotillomania, a compulsive urge to pull out one's own hair, is another important differential that may require psychological support. Understanding the root cause is essential before pursuing any treatment, as management strategies differ considerably depending on the underlying aetiology.
Further information: NHS – Hair loss (alopecia); BAD Patient Information Leaflets; NICE CKS – Alopecia areata.
| Cause | Type of Hair Loss | Who Is Affected | Key Features | Reversible? | When to Seek Help |
|---|---|---|---|---|---|
| Androgenetic alopecia (male/female-pattern) | Progressive thinning, patterned | ~50% of men by age 50; up to 40% of women by age 70 | DHT-driven follicle miniaturisation; worsens after menopause in women | No, but manageable | If causing distress or rapid progression |
| Telogen effluvium | Diffuse shedding, temporary | Any age; common postpartum or after illness | Triggered by stress, surgery, childbirth, iron deficiency, or crash dieting | Yes, usually within 6–12 months | If shedding persists beyond 6–12 months |
| Alopecia areata | Patchy, non-scarring | ~2% lifetime prevalence; any age | Autoimmune attack on follicles; can progress to total scalp or body hair loss | Often yes, but unpredictable | At onset; urgent if rapidly spreading |
| Thyroid disorders / iron deficiency / PCOS | Diffuse thinning | Women of reproductive age most commonly | Treatable systemic causes; ferritin, TFTs, and hormone profile guide diagnosis | Yes, with treatment of underlying condition | If accompanied by fatigue, weight change, or irregular periods |
| Drug-induced (e.g., warfarin, beta-blockers, isotretinoin, sodium valproate) | Usually diffuse telogen effluvium | Any patient on implicated medicines | MHRA-documented adverse effect; do not stop medication without GP advice | Often yes, after review with prescriber | Discuss with GP; report via MHRA Yellow Card Scheme |
| Traction alopecia | Recession at hairline/temples | Those using tight hairstyles, extensions, or chemical treatments | Preventable; caused by prolonged mechanical tension on follicles | Yes, if identified early and cause removed | At first signs of hairline recession |
| Scarring alopecia (e.g., lichen planopilaris, lupus, kerion) | Permanent follicle destruction | Any age; kerion more common in children | Scalp may appear shiny or smooth; inflammation present; urgent treatment needed | No — permanent if untreated | Urgent dermatology referral required |
Medical Conditions Linked to Hair Loss
Thyroid disorders and iron deficiency are among the most important treatable medical causes of hair loss; autoimmune conditions such as alopecia areata and lupus, and scalp infections such as tinea capitis, also require consideration.
A number of systemic and dermatological conditions are well-established causes of hair loss, and identifying these is a key part of clinical assessment. Thyroid disorders — both hypothyroidism and hyperthyroidism — are among the most frequently implicated medical causes. Thyroid hormones play a central role in regulating the hair growth cycle, and disruption can result in diffuse thinning across the scalp.
Iron deficiency is another important and treatable cause, particularly in women of reproductive age. Low ferritin levels, even in the absence of frank anaemia, have been associated with increased hair shedding; however, the threshold at which iron repletion improves hair loss is debated, and management should follow local clinical guidance. Polycystic ovary syndrome (PCOS) can cause androgenic hair loss in women due to elevated androgen levels, typically accompanied by other features of hyperandrogenism such as irregular periods, hirsutism, or acne. Hormone testing is most appropriate when these features are present, rather than as a routine investigation for all women with hair loss.
Autoimmune conditions deserve particular attention:
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Alopecia areata — patchy, non-scarring hair loss caused by immune-mediated attack on hair follicles
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Lupus (SLE) — can cause both diffuse thinning and scarring alopecia
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Lichen planopilaris — a form of scarring alopecia associated with follicular inflammation
Scalp conditions such as tinea capitis (a fungal infection more common in children) and seborrhoeic dermatitis may also be associated with hair shedding. It is important to note that seborrhoeic dermatitis does not typically cause permanent hair loss and usually responds well to treatment with antifungal shampoos and topical anti-inflammatory agents. Tinea capitis, however, can occasionally present as a kerion — a severe inflammatory reaction — which should be treated urgently with oral antifungal therapy and referred promptly to prevent scarring and permanent follicle loss.
Scarring alopecias more broadly are particularly important to identify early, as permanent follicle destruction can occur if treatment is delayed. Any suspicion of a scarring process should prompt urgent referral to a dermatologist.
Further information: NICE CKS – Alopecia areata; PCDS – Scarring alopecia; Tinea capitis; BAD Guidelines on lichen planopilaris.
Medications and Treatments That Can Cause Hair Loss
A wide range of medications — including anticoagulants, beta-blockers, retinoids, and chemotherapy agents — can cause hair loss; patients should not stop prescribed medicines without consulting their GP or specialist.
Drug-induced hair loss is a recognised but often overlooked cause, and it is important for both patients and clinicians to be aware of the medications most commonly implicated. The MHRA and EMA have documented hair loss as an adverse effect for a wide range of medicines. The mechanism typically involves disruption of the normal hair growth cycle, most often precipitating a telogen effluvium-type response. The following list is illustrative, not exhaustive.
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Medications commonly associated with hair loss include:
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Anticoagulants such as warfarin and heparin
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Beta-blockers (e.g., atenolol, propranolol) used for cardiovascular conditions
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Retinoids (e.g., isotretinoin for acne) — known to cause dose-dependent hair thinning
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Antidepressants, including some SSRIs and tricyclics
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Mood stabilisers such as lithium and sodium valproate
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Oral contraceptives, particularly those with higher androgenic activity
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Antithyroid drugs such as carbimazole
For medicine-specific adverse effect information, patients and clinicians should consult the Patient Information Leaflet (PIL) or Summary of Product Characteristics (SmPC), available via the Electronic Medicines Compendium (EMC), and the British National Formulary (BNF).
Chemotherapy represents a distinct category, causing anagen effluvium — a rapid, often complete hair loss resulting from direct damage to actively dividing hair follicle cells. This is usually temporary, with regrowth expected after treatment concludes, though hair texture or colour may change. The NHS provides scalp cooling services in many oncology units, which can help reduce chemotherapy-related hair loss; further information is available on the NHS website.
It is important that patients do not stop prescribed medications without first consulting their GP or specialist, even if they suspect a drug is contributing to hair loss. Not all reports of hair loss imply causation; the benefit–risk balance must always be carefully considered with the prescribing clinician. If a patient suspects a medicine is causing hair loss, this can be reported to the MHRA via the Yellow Card Scheme at yellowcard.mhra.gov.uk.
Further information: MHRA/EMC SmPCs for listed medicines; BNF adverse effects sections; NHS – Scalp cooling during chemotherapy.
When to See a GP About Hair Loss
You should see a GP promptly if hair loss is sudden, patchy, accompanied by scalp changes or systemic symptoms, or if scarring alopecia is suspected, as early treatment can prevent permanent follicle loss.
Many people experience some degree of hair shedding throughout their lives, and not all hair loss requires medical attention. However, there are specific circumstances in which it is advisable to seek a GP assessment promptly. Early consultation is particularly important when hair loss is sudden, rapid, or accompanied by other symptoms that may suggest an underlying medical condition.
You should contact your GP if you notice:
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Sudden or patchy hair loss appearing over a short period
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Hair loss accompanied by scalp redness, scaling, itching, or pain
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Diffuse thinning that is worsening despite no obvious lifestyle trigger
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Hair loss alongside symptoms such as fatigue, weight changes, or irregular periods
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Hair loss in a child, which may indicate tinea capitis or alopecia areata
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Signs of scarring on the scalp, such as shiny or smooth skin where hair has been lost
Urgent or expedited referral to a dermatologist is appropriate if scarring alopecia is suspected or if a child presents with a painful, inflamed scalp mass (kerion), as prompt treatment is needed to prevent permanent hair loss.
If you regularly wear tight hairstyles, hair extensions, or use chemical treatments and have noticed hair thinning or recession at the hairline or temples, mention this to your GP, as traction alopecia is preventable and often improves when the cause is removed.
It is also worth seeking advice if hair loss is causing significant psychological distress. The NHS recognises that hair loss can have a profound impact on self-esteem and mental wellbeing, and GPs can refer patients to appropriate support services, including dermatology and psychological therapies where indicated.
In most cases, a GP will begin with a thorough history and examination before arranging blood tests. Patients are encouraged to keep a note of when the hair loss started, any recent illnesses or stressors, current medications, and any family history of hair loss, as this information greatly assists diagnosis.
Further information: NHS – Hair loss (when to see a GP); NICE CKS – Alopecia areata (referral advice); PCDS – Hair loss red flags in primary care.
Diagnosis and Tests Available on the NHS
NHS diagnosis begins with clinical history and examination; baseline blood tests include FBC, serum ferritin, and thyroid function tests, with further investigations such as hormone profiles or scalp biopsy guided by clinical findings.
Diagnosing the cause of hair loss involves a combination of clinical history, physical examination, and targeted investigations. A GP will typically begin by assessing the pattern and distribution of hair loss — whether it is diffuse, patchy, or follows a specific pattern — alongside examination of the scalp for signs of inflammation, scarring, or infection.
Baseline blood tests commonly requested on the NHS include:
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Full blood count (FBC) — to identify anaemia
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Serum ferritin — a sensitive marker of iron stores
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Thyroid function tests (TFTs) — to exclude hypothyroidism or hyperthyroidism
Additional investigations are guided by the clinical history and examination findings, rather than being requested routinely for all patients:
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Hormone profile (including testosterone, DHEAS, and sex hormone-binding globulin) — indicated in women with signs of hyperandrogenism (e.g., irregular periods, hirsutism, acne) or suspected PCOS
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Vitamin D and B12 levels — where risk factors for deficiency are present (e.g., limited sun exposure, malabsorption, restrictive diet)
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Coeliac serology — if unexplained iron deficiency or malabsorption is suspected
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Inflammatory markers (ESR, CRP) — if autoimmune disease is suspected
This risk-factor-driven approach is consistent with NICE CKS, BAD, and PCDS guidance, and helps avoid unnecessary over-investigation.
In some cases, a scalp biopsy may be required to differentiate between scarring and non-scarring alopecias, or to confirm a specific diagnosis such as lichen planopilaris. This is usually arranged via a dermatology referral. Trichoscopy — a non-invasive dermoscopic examination of the scalp and hair follicles — is increasingly used in specialist settings to aid diagnosis without the need for biopsy.
Referral to a consultant dermatologist is appropriate when the diagnosis is uncertain, when scarring alopecia is suspected, or when initial treatments have not produced the expected response.
Further information: NICE CKS – Female pattern hair loss; Alopecia areata; PCDS – Hair loss workup in primary care; BAD guidelines and position statements.
Treatment Options and Support for Hair Loss
Treatment is cause-specific; options include topical minoxidil and prescription finasteride for androgenetic alopecia, corticosteroids or baricitinib for alopecia areata, and NHS wigs and psychological support for eligible patients.
Treatment for hair loss depends entirely on the underlying cause, and a one-size-fits-all approach is not appropriate. Where a reversible cause is identified — such as iron deficiency, thyroid dysfunction, or a causative medication — addressing that underlying condition is the primary intervention and often leads to natural hair regrowth over several months.
For androgenetic alopecia, the following evidence-based options are available:
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Minoxidil (available over the counter as a topical solution or foam) — licensed in the UK for both men and women, though licensed strengths differ by sex (2% and 5% formulations; check product labelling). It prolongs the anagen (growth) phase of the hair cycle and increases follicle size. Results typically take three to six months to become apparent. Common adverse effects include scalp irritation and unwanted facial or body hair (hypertrichosis). Importantly, benefits are maintained only with continued use and will reverse if treatment is stopped.
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Finasteride (oral, prescription-only for men) — a 5-alpha reductase inhibitor that reduces DHT levels. Men should discuss the benefit–risk balance with their GP before starting, as the MHRA has issued Drug Safety Updates highlighting risks of sexual dysfunction (which may persist after stopping) and mood changes including depression and suicidal ideation. Finasteride also lowers PSA levels, which should be taken into account when interpreting prostate cancer screening results. It is contraindicated in women of childbearing potential due to teratogenic risk; women who are pregnant or may become pregnant should not handle crushed or broken tablets.
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Dutasteride — used off-label in some specialist settings for male androgenetic alopecia; initiation should be under specialist supervision.
For alopecia areata, treatment options include potent topical corticosteroids, intralesional steroid injections, and — in more extensive cases — immunotherapy with diphencyprone (DPCP), available in specialist dermatology centres. The JAK inhibitor baricitinib has received MHRA approval in the UK for severe alopecia areata in adults and has been appraised by NICE (NICE Technology Appraisal TA885); eligibility criteria apply and prescribing should follow current NHS commissioning guidance. As with all JAK inhibitors, safety monitoring (including infection risk, cardiovascular risk, and malignancy) is required; patients should be counselled accordingly by their specialist.
For tinea capitis, oral antifungal treatment (typically terbinafine or griseofulvin, guided by local guidance and patient age) is required; contact screening may be appropriate. For seborrhoeic dermatitis, first-line treatment includes ketoconazole shampoo and topical anti-inflammatory agents; this condition does not typically cause permanent hair loss.
Beyond medical treatment, the NHS and charitable organisations such as Alopecia UK and the British Association of Dermatologists (BAD) offer valuable support resources. Wigs are available on the NHS for patients with certain medical conditions causing hair loss, including alopecia areata and chemotherapy-related hair loss. Psychological support, including cognitive behavioural therapy (CBT), may be beneficial for those experiencing significant distress; GPs can facilitate referrals through NHS Talking Therapies (formerly IAPT) services.
If you suspect a medicine is causing hair loss, report it to the MHRA via the Yellow Card Scheme at yellowcard.mhra.gov.uk and discuss with your prescriber before making any changes to your treatment.
Further information: MHRA Drug Safety Update – Finasteride (sexual dysfunction; depression and suicidal ideation); EMC SmPC – Minoxidil topical; Finasteride 1 mg; NICE TA885 – Baricitinib for severe alopecia areata; NHS Talking Therapies; BAD Patient Information Leaflets (Alopecia areata; Androgenetic alopecia); BNF monographs.
Frequently Asked Questions
What are the most common causes of hair loss in the UK?
The most common cause is androgenetic alopecia (male- or female-pattern baldness), driven by sensitivity to DHT. Other frequent causes include telogen effluvium following illness or stress, alopecia areata, iron deficiency, thyroid disorders, and traction alopecia from tight hairstyles.
When should I see a GP about hair loss?
You should see a GP if hair loss is sudden, patchy, or accompanied by scalp redness, pain, or scaling, or if you have other symptoms such as fatigue or irregular periods. Suspected scarring alopecia or hair loss in a child warrants prompt referral to a dermatologist.
Can medications cause hair loss?
Yes, a range of medications including anticoagulants, beta-blockers, retinoids, certain antidepressants, and chemotherapy drugs are recognised causes of hair loss. Patients should not stop prescribed medicines without first consulting their GP or specialist, as the benefit–risk balance must be carefully considered.
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The information on this site is not a substitute for professional medical advice. For any health concerns, please speak with a qualified medical professional. By using this information, you acknowledge responsibility for any decisions made and understand we are not liable for any consequences that may result.
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