What causes alopecia hair loss is a question that affects millions of people across the UK, from children to older adults. Alopecia — the medical term for hair loss — can range from mild thinning to complete baldness and may affect the scalp, face, or body. Causes are wide-ranging, including genetics, autoimmune conditions, hormonal imbalances, nutritional deficiencies, and certain medications. Understanding the specific type and underlying trigger is essential, as treatment approaches and prognosis vary considerably. This article explains the main causes, when to seek NHS assessment, and the evidence-based treatment options available in the UK.
Summary: Alopecia hair loss is caused by a range of factors including genetic predisposition, autoimmune responses, hormonal imbalances, nutritional deficiencies, physical or emotional stress, scalp conditions, and certain medications.
- Androgenetic alopecia, driven by the hormone DHT in genetically susceptible individuals, is the most common cause of hair loss in both men and women.
- Alopecia areata is an autoimmune condition in which the immune system attacks hair follicles, causing patchy hair loss; it is associated with thyroid disease and vitiligo.
- Telogen effluvium is triggered by physiological stressors such as childbirth, illness, or rapid weight loss, causing diffuse shedding two to three months after the event.
- Scarring alopecias permanently destroy hair follicles and require prompt dermatology referral to prevent irreversible loss.
- Medications including chemotherapy agents, anticoagulants, retinoids, and some hormonal contraceptives are recognised causes of hair loss; patients should not stop prescribed medicines without consulting their GP.
- JAK inhibitors such as ritlecitinib (Litfulo) have received MHRA approval and NICE appraisal for severe alopecia areata and must be initiated and monitored by a specialist.
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Understanding Alopecia and the Types of Hair Loss
Alopecia encompasses several distinct types of hair loss — including androgenetic alopecia, alopecia areata, telogen effluvium, and scarring alopecias — each with different causes, prognoses, and treatments. Suspected scarring alopecia requires prompt dermatology referral to prevent permanent follicle damage.
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Alopecia is the medical term for hair loss, and it can affect the scalp, face, and other areas of the body. Hair loss is common and can affect both men and women, as well as children. It can range from mild thinning to complete baldness, and understanding the type of alopecia involved is the first step towards appropriate management.
There are several recognised forms of alopecia, each with distinct characteristics:
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Androgenetic alopecia (male- or female-pattern baldness): the most common type, caused by a combination of genetic predisposition and hormonal factors.
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Alopecia areata: an autoimmune condition causing patchy hair loss on the scalp or body.
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Alopecia totalis: complete loss of scalp hair.
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Alopecia universalis: total loss of all body hair.
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Telogen effluvium: diffuse shedding triggered by physical or emotional stress, illness, or hormonal changes.
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Traction alopecia: hair loss caused by prolonged tension on the hair follicles, often related to certain hairstyles.
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Trichotillomania: a hair-pulling disorder that can cause patchy hair loss, particularly in children and adolescents; psychological or behavioural assessment is an important part of management.
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Scarring (cicatricial) alopecia: a group of rarer conditions — including lichen planopilaris, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia — in which inflammation permanently destroys hair follicles.
It is important to distinguish between these types because the underlying causes, prognosis, and treatment approaches differ considerably. Some forms of hair loss are temporary and reversible, whilst others — particularly scarring alopecias — may result in permanent follicle damage if not identified and treated promptly. Suspected scarring alopecia warrants prompt referral to a dermatologist to minimise irreversible loss. A thorough clinical assessment is therefore essential before any management plan is initiated.
| Type of Alopecia | Primary Cause | Who Is Affected | Reversible? | When to Seek Help |
|---|---|---|---|---|
| Androgenetic alopecia | Genetic predisposition; DHT-driven follicle miniaturisation | ~50% of men by age 50; women post-menopause | Partially; treatable but not curable | GP if causing distress; early treatment yields better outcomes |
| Alopecia areata | Autoimmune attack on hair follicles; associated with thyroid disease, vitiligo | Any age, including children | Often yes, but unpredictable | GP; dermatology referral if extensive or progressive |
| Telogen effluvium | Physiological stress: childbirth, rapid weight loss, major surgery, severe illness | Predominantly women; any adult | Yes; usually resolves within 6–12 months | GP if shedding persists beyond 6 months or cause is unclear |
| Scarring (cicatricial) alopecia | Inflammation permanently destroys follicles; includes lichen planopilaris, frontal fibrosing alopecia | Adults; varies by subtype | No; permanent if untreated | Prompt dermatology referral to prevent irreversible loss |
| Traction alopecia | Prolonged mechanical tension from tight braids, weaves, or extensions | Any age; common in those with certain hairstyling practices | Yes, if caught early | GP if hair loss persists after changing hairstyle |
| Drug-induced hair loss | Chemotherapy, anticoagulants, retinoids, beta-blockers, some SSRIs, hormonal contraceptives | Anyone on implicated medicines | Often yes, after stopping causative drug | Consult GP before stopping any prescribed medication; report via MHRA Yellow Card |
| Nutritional / hormonal causes | Iron deficiency, thyroid dysfunction, PCOS, elevated androgens | Women of reproductive age most commonly | Yes, with treatment of underlying condition | GP for targeted blood tests: FBC, ferritin, TFTs, hormone profile |
Common Causes of Alopecia in Adults and Children
Androgenetic alopecia is the most common cause in adults, whilst alopecia areata and tinea capitis are frequent causes in children. Other key triggers include telogen effluvium, iron deficiency, hormonal imbalances such as PCOS, and traction from tight hairstyles.
Hair loss has a wide range of causes, and identifying the trigger is central to effective treatment. In adults, androgenetic alopecia is by far the most prevalent cause. It affects approximately 50% of men by the age of 50 and a significant proportion of women, particularly after the menopause. This type is driven by the hormone dihydrotestosterone (DHT), which causes progressive miniaturisation of hair follicles in genetically susceptible individuals.
Telogen effluvium is another frequently encountered cause, particularly in women. It occurs when a significant physiological stressor — such as childbirth, rapid weight loss, major surgery, or severe illness — pushes a large number of hair follicles prematurely into the resting (telogen) phase. Shedding typically becomes noticeable two to three months after the triggering event and usually resolves spontaneously within six to twelve months.
In children, alopecia areata is one of the most common causes of patchy hair loss. It is an autoimmune condition in which the immune system mistakenly attacks hair follicles. Whilst the exact trigger is not fully understood, there is a recognised association with other autoimmune conditions such as thyroid disease and vitiligo. Stress and genetic factors are also thought to play a role. Trichotillomania should also be considered in children and adolescents presenting with patchy or irregular hair loss; characteristic findings include broken hairs of varying lengths, and appropriate psychological or behavioural support should be sought.
Other common causes across age groups include:
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Nutritional deficiencies: iron deficiency (with or without anaemia) and inadequate protein intake are the most clinically relevant. Zinc deficiency is sometimes implicated, though the evidence supporting routine zinc testing in hair loss is limited; testing should be guided by clinical risk factors rather than performed routinely.
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Hormonal imbalances: including polycystic ovary syndrome (PCOS) and thyroid dysfunction.
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Scalp conditions: such as tinea capitis (a fungal infection more common in children) and seborrhoeic dermatitis. Tinea capitis requires systemic antifungal treatment. A painful, boggy, inflammatory scalp mass known as a kerion is a complication of tinea capitis that requires urgent assessment and treatment to prevent scarring alopecia.
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Traction alopecia: increasingly recognised in individuals who regularly wear tight braids, weaves, or extensions.
Medical Conditions and Medications Linked to Hair Loss
Thyroid disorders, lupus, PCOS, and iron deficiency are established medical causes of hair loss, and treating the underlying condition often leads to regrowth. Medications including chemotherapy agents, anticoagulants, and retinoids can also cause hair loss; patients should not stop prescribed medicines without GP advice.
A number of underlying medical conditions are directly associated with hair loss, and in many cases, treating the primary condition leads to hair regrowth. Thyroid disorders — both hypothyroidism and hyperthyroidism — are well-established causes of diffuse hair thinning. Thyroid hormones play a key role in regulating the hair growth cycle, and imbalances can disrupt this process significantly.
Autoimmune conditions such as lupus (systemic lupus erythematosus) can cause both scarring and non-scarring hair loss. Iron deficiency, even in the absence of frank anaemia, is a commonly identified contributor to hair shedding in women of reproductive age, though the precise ferritin threshold at which treatment benefits hair regrowth remains debated; management should follow standard iron deficiency guidance and be guided by clinical context. PCOS leads to elevated androgen levels, which can cause androgenetic-pattern hair loss alongside other symptoms such as irregular periods and acne.
Several medications are also known to cause hair loss as a side effect. Individual responses vary, and not everyone taking these medicines will be affected. Patients should not stop any prescribed medication without first consulting their GP or specialist. Medication classes commonly associated with hair loss include:
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Chemotherapy agents: cause anagen effluvium by disrupting rapidly dividing hair follicle cells.
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Anticoagulants: such as warfarin and heparin.
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Retinoids: including isotretinoin and other high-dose vitamin A derivatives.
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Antithyroid drugs, beta-blockers, and certain antidepressants (for example, some SSRIs in susceptible individuals).
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Hormonal contraceptives: in some individuals, particularly those with an underlying sensitivity to androgens.
If you suspect a medicine is causing hair loss, speak to your GP or pharmacist before making any changes. Suspected adverse drug reactions — including drug-induced hair loss — can be reported directly to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. This helps the MHRA monitor the safety of medicines used in the UK.
When to See a GP About Hair Loss
You should see a GP if hair loss is sudden, patchy, painful, accompanied by systemic symptoms, or occurs in a child. Urgent assessment is needed for a boggy scalp lesion or signs of scarring alopecia, as early intervention can prevent permanent hair loss.
Many people experience some degree of hair shedding throughout their lives, and not all hair loss requires urgent medical attention. However, there are specific circumstances in which it is important to seek a GP assessment promptly to rule out an underlying condition or prevent further follicle damage.
You should contact your GP if you notice:
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Sudden or rapid hair loss over a short period.
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Patchy hair loss, particularly if the patches are smooth and well-defined.
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Hair loss accompanied by scalp redness, scaling, itching, or pain — which may suggest a treatable scalp condition.
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Hair loss alongside other symptoms such as fatigue, weight changes, irregular periods, or skin changes, which could indicate a systemic condition.
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Hair loss in a child, which should always be assessed to exclude tinea capitis, alopecia areata, or trichotillomania.
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Hair loss that began after starting a new medicine or following a dose change.
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Eyebrow or eyelash loss, or nail changes such as pitting, which can be associated with alopecia areata.
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Significant psychological distress related to hair loss, as this can have a considerable impact on mental health and quality of life.
Seek prompt or urgent assessment if you notice a painful, boggy, or purulent scalp lesion (which may indicate a kerion), pustules or folliculitis, or signs that may suggest scarring alopecia — such as loss of visible follicular openings, persistent redness, or scaling at the hairline. Early referral to a dermatologist in these cases can help prevent permanent hair loss.
Whilst androgenetic alopecia does not require urgent investigation, early intervention with evidence-based treatments tends to yield better outcomes. Patients should feel reassured that hair loss is a legitimate medical concern and that GPs are well-placed to carry out an initial assessment, arrange relevant blood tests, and refer to a dermatologist where necessary. Emotional support and signposting to organisations such as Alopecia UK can also be valuable.
Diagnosis and Assessment on the NHS
GP assessment begins with a clinical history and targeted blood tests — including FBC, serum ferritin, and thyroid function — guided by the individual's presentation. Complex cases are referred to an NHS dermatologist, who may use dermoscopy or scalp biopsy to confirm the diagnosis.
When a patient presents to their GP with hair loss, the assessment typically begins with a detailed clinical history and physical examination. The GP will ask about the pattern and duration of hair loss, any recent illnesses, dietary changes, medications, family history, and associated symptoms. This information helps to narrow down the likely cause before any investigations are arranged.
Investigations are targeted to the individual's clinical presentation rather than performed as a routine broad panel. A targeted blood panel may include:
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Full blood count (FBC): to identify anaemia.
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Serum ferritin: a sensitive marker of iron stores, often low in women with hair shedding.
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Thyroid function tests (TFTs): to detect hypothyroidism or hyperthyroidism.
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Hormone profile: including testosterone, sex hormone-binding globulin (SHBG), and prolactin — requested selectively in women with clinical features suggesting PCOS or androgen excess.
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Inflammatory markers and autoimmune screen: only where lupus or another autoimmune condition is clinically suspected.
For more complex or uncertain presentations, referral to an NHS dermatologist is appropriate. Dermatologists can perform dermoscopy (trichoscopy) — a non-invasive technique using a handheld magnifying device to examine the scalp and hair follicles in detail. In some cases, a scalp biopsy may be required to confirm a diagnosis of scarring alopecia or to distinguish between subtypes. If you are considering consulting a trichologist privately, it is worth noting that trichologists are not medically qualified and are not a standard NHS referral endpoint.
Whilst there is no single dedicated NICE guideline for alopecia, relevant guidance exists across several resources including NICE Clinical Knowledge Summaries (CKS) for alopecia areata and male-pattern hair loss, NICE technology appraisals for newer treatments, and guidance from the Primary Care Dermatology Society (PCDS) and the British Association of Dermatologists (BAD). Clinical management is therefore guided by established dermatological practice, NHS pathways, and investigations tailored to the individual patient's presentation.
Treatment Options and Managing Alopecia in the UK
Treatment depends on the type and cause of alopecia; options include over-the-counter minoxidil and prescription finasteride for androgenetic alopecia, and corticosteroids or JAK inhibitors for alopecia areata. Telogen effluvium usually resolves by addressing the underlying trigger, and psychological support is an important part of overall care.
Treatment for alopecia depends entirely on the underlying cause, the type of hair loss, and the individual's preferences and expectations. It is important for patients to understand that not all hair loss is reversible, and that treatment aims to slow progression, stimulate regrowth where possible, and support psychological wellbeing.
For androgenetic alopecia, the following evidence-based options are available:
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Minoxidil (topical solution or foam): available over the counter in the UK for both men and women. It prolongs the anagen (growth) phase of the hair cycle and is the most widely used first-line treatment. A minimum of three to six months of consistent use is needed before assessing response, and continued use is required to maintain any benefit. Common adverse effects include scalp irritation and unwanted hair growth (hypertrichosis) at application sites.
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Finasteride (oral, 1 mg daily): licensed in the UK for adult men only. It works by inhibiting the conversion of testosterone to DHT. Finasteride is contraindicated in women, particularly during pregnancy, due to the risk of feminisation of a male foetus. The MHRA has issued safety warnings regarding potential adverse effects in men, including sexual dysfunction and mood changes (including depression and, rarely, suicidal ideation); patients should discuss these risks with their prescriber before starting treatment.
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Low-level laser therapy (LLLT): some studies suggest a modest benefit as an adjunct treatment, but the evidence is limited and heterogeneous. LLLT is not routinely commissioned on the NHS.
For alopecia areata, it is important to note that mild or limited disease may remit spontaneously, and a period of watchful waiting is appropriate in many cases. Where treatment is indicated, options include:
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Potent topical corticosteroids: first-line for patchy alopecia areata.
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Intralesional corticosteroid injections: administered by a dermatologist for localised patches.
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Immunotherapy (diphencyprone/DPCP): used in specialist centres for extensive or treatment-resistant cases.
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JAK inhibitors: a newer class of targeted therapy. Ritlecitinib (Litfulo) received MHRA approval for severe alopecia areata in people aged 12 years and over, and has been appraised by NICE (Technology Appraisal, 2024) for use within the NHS under specified criteria. Baricitinib has also been studied in alopecia areata; patients and clinicians should refer to the current MHRA/EMC Summary of Product Characteristics and NICE guidance for up-to-date licensing and commissioning status. JAK inhibitors carry important safety considerations including increased risk of serious infection, venous thromboembolism, and malignancy; they should be initiated and monitored by a specialist.
For telogen effluvium, addressing the underlying trigger — such as correcting nutritional deficiencies or managing stress — is usually sufficient, as regrowth typically occurs naturally.
Beyond medical treatment, psychological support is an important component of care. Organisations such as Alopecia UK offer peer support, and NHS Talking Therapies for anxiety and depression can help those experiencing significant distress (see nhs.uk/mental-health/talking-therapies-medicine-treatments/talking-therapies-and-counselling/nhs-talking-therapies). Wigs and hairpieces are available on the NHS for certain conditions, including alopecia areata, subject to local commissioning policies; eligibility criteria and any applicable charges or exemptions vary by area.
Frequently Asked Questions
What is the most common cause of alopecia hair loss in the UK?
Androgenetic alopecia (male- or female-pattern baldness) is the most common cause, affecting around 50% of men by age 50 and a significant proportion of women, particularly after the menopause. It is driven by the hormone dihydrotestosterone (DHT) acting on genetically susceptible hair follicles.
Can alopecia hair loss be caused by stress or illness?
Yes — telogen effluvium is a form of diffuse hair shedding triggered by significant physical or emotional stress, including severe illness, major surgery, or childbirth. Shedding typically begins two to three months after the triggering event and usually resolves spontaneously within six to twelve months.
When should I see a GP about alopecia hair loss?
You should see a GP if hair loss is sudden, patchy, or accompanied by scalp symptoms such as redness, pain, or scaling, or if it occurs alongside systemic symptoms like fatigue or weight changes. Urgent assessment is needed if you notice a painful, boggy scalp lesion or signs of scarring alopecia, as early treatment can prevent permanent follicle damage.
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