Does low testosterone cause hair loss? It is a question many people ask, yet the relationship between testosterone and scalp hair is far more nuanced than commonly assumed. Whilst testosterone and its derivative dihydrotestosterone (DHT) do influence hair follicle behaviour, low testosterone is not a direct cause of scalp hair loss. Understanding the hormonal mechanisms involved — and the many other factors that contribute to hair thinning — is essential before seeking diagnosis or treatment. This article explains the science, outlines when to seek medical advice, and summarises the evidence-based options available through the NHS.

How Testosterone Levels Affect Hair Growth

Low testosterone is not a direct cause of scalp hair loss; androgens stimulate body and facial hair but paradoxically contribute to scalp thinning only in genetically predisposed individuals.

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Testosterone is a steroid hormone produced primarily in the testes in men and, in smaller quantities, in the ovaries and adrenal glands in women. It plays a central role in a wide range of physiological processes, including muscle development, bone density, libido, and mood regulation. Its relationship with hair growth, however, is nuanced and often misunderstood.

Hair follicles are sensitive to androgens — the group of hormones that includes testosterone — but the effect varies considerably depending on the location of the follicle on the body. Androgens generally stimulate hair growth on the face, chest, and body, whilst paradoxically contributing to hair thinning or loss on the scalp in genetically predisposed individuals.

Importantly, low testosterone itself is not a direct cause of scalp hair loss. Some observational data have suggested that men with lower testosterone levels may experience less androgenetic alopecia than those with higher levels, though this relationship is not straightforward and should not be taken to mean that hair loss signals low testosterone. The picture is considerably more complex, and other factors — including genetics, thyroid function, nutritional status, and stress — play equally significant roles in hair health. The NHS notes that hair loss is very common and has many possible causes beyond hormonal changes.

The Role of DHT in Male and Female Hair Loss

DHT, produced from testosterone via 5-alpha reductase, drives pattern hair loss by miniaturising scalp follicles; follicle sensitivity to DHT — not absolute hormone levels — determines susceptibility.

The key hormonal driver of pattern hair loss is not testosterone itself, but rather dihydrotestosterone (DHT) — a potent androgen derived from testosterone through the action of an enzyme called 5-alpha reductase. DHT binds to androgen receptors in scalp hair follicles, causing them to miniaturise over time. This process, known as follicular miniaturisation, leads to progressively finer, shorter hairs and, eventually, follicle dormancy.

In men, this manifests as androgenetic alopecia — the classic receding hairline and crown thinning. In women, the pattern is typically more diffuse, presenting as a widening parting or generalised thinning across the top of the scalp, rather than complete baldness. Whilst DHT may contribute to hair loss in some women — particularly after the menopause, when falling oestrogen levels reduce its counterbalancing effect — it is important to note that many women with female pattern hair loss have entirely normal circulating androgen levels. The condition in women is polygenic and multifactorial, and androgens are only one part of the picture.

Crucially, it is the sensitivity of the hair follicle to DHT, rather than the absolute level of testosterone or DHT in the bloodstream, that largely determines susceptibility to pattern hair loss. This explains why some individuals with normal or even low testosterone levels still experience significant hair thinning, whilst others with high testosterone retain a full head of hair. Genetic predisposition — particularly variants in the androgen receptor gene — is the dominant factor in this sensitivity, as recognised by the British Association of Dermatologists (BAD) and the Primary Care Dermatology Society (PCDS).

Recognising Symptoms of Low Testosterone

Low testosterone presents with reduced libido, fatigue, low mood, reduced muscle mass, and loss of body and facial hair — scalp hair loss is not a hallmark symptom.

Low testosterone, clinically referred to as hypogonadism or testosterone deficiency syndrome, presents with a constellation of symptoms that extend well beyond hair changes. Recognising these symptoms is important, as they can significantly affect quality of life and may indicate an underlying medical condition requiring investigation.

Common symptoms of low testosterone in men include:

• Reduced libido and sexual dysfunction, including erectile difficulties

• Fatigue and low energy, often described as persistent and disproportionate to activity levels

• Mood changes, including low mood, irritability, and difficulty concentrating

• Reduced muscle mass and strength, alongside increased body fat, particularly around the abdomen

• Decreased bone density, which may increase fracture risk over time

• Reduced body and facial hair — this refers to hair loss in androgen-dependent areas (beard, chest, axillary, and pubic hair), which is distinct from scalp hair loss

In women, testosterone testing is not routine and should generally be specialist-led. The main UK-recognised indication for testosterone therapy in women is hypoactive sexual desire disorder (HSDD) in postmenopausal women, as outlined in NICE guidance. Symptoms such as fatigue, low mood, and reduced libido in women have many possible causes and should be assessed comprehensively rather than attributed to low testosterone without specialist evaluation.

It is worth emphasising that scalp hair loss is not a hallmark symptom of low testosterone. If scalp hair thinning is occurring alongside the symptoms listed above, it is more likely that multiple factors are at play. Conditions such as hypothyroidism, iron deficiency anaemia, or telogen effluvium (stress-related shedding) can cause hair loss independently of testosterone levels and should be considered in any thorough assessment.

When to Speak to a GP About Hair Loss and Hormones

Consult a GP if hair loss is sudden, patchy, or accompanied by fatigue, weight changes, or reduced libido; testosterone is prescription-only and self-treatment is not appropriate.

Hair loss is common and, in many cases, does not require urgent medical attention. However, there are circumstances in which it is advisable to consult a GP, particularly when hair loss is accompanied by other symptoms that may suggest an underlying hormonal or systemic condition.

Consider speaking to your GP if you notice:

• Sudden or rapid hair loss, or loss in patches (which may suggest alopecia areata)

• Hair thinning accompanied by fatigue, weight changes, or cold intolerance (possible thyroid dysfunction)

• Hair loss alongside symptoms of low testosterone, such as reduced libido, low mood, or loss of muscle mass

• Hair loss in women that is diffuse or associated with menstrual irregularities or signs of excess androgens (such as acne or facial hair growth), which may warrant assessment for polycystic ovary syndrome (PCOS)

• Hair loss following a significant illness, surgery, or period of intense stress

Seek prompt medical advice if you notice:

• Scalp inflammation, redness, pustules, pain, or bleeding alongside hair loss — these may suggest scarring alopecia or infection and warrant urgent assessment

• Patchy hair loss with scaling, broken hairs, or swollen lymph nodes in the neck, which may indicate tinea capitis (a fungal infection), particularly in children

• Rapid or widespread hair loss that is causing significant distress

Your GP can help distinguish between the various causes of hair loss and determine whether hormonal testing or referral to a dermatologist is appropriate. It is important not to self-diagnose or self-treat. Testosterone is a prescription-only medicine in the UK — it cannot be purchased over the counter. Supplements marketed as 'testosterone boosters' are not testosterone and are unregulated; the MHRA advises caution with unlicensed hormonal products available online, as their safety and efficacy cannot be guaranteed. Guidance on buying medicines safely online is available from the MHRA. A structured clinical assessment is always the safest starting point.

Diagnosis and Testing on the NHS

GPs test for low testosterone using two fasting morning serum testosterone measurements, alongside LH, FSH, SHBG, thyroid function, and ferritin to exclude other causes of hair loss.

If a GP suspects that hair loss may be related to a hormonal imbalance, they will typically begin with a thorough clinical history and physical examination before requesting blood tests. This approach aligns with NICE Clinical Knowledge Summaries (CKS) on testosterone deficiency in men and guidance from the British Society for Sexual Medicine (BSSM) and the Society for Endocrinology.

For suspected low testosterone in men, blood tests will usually include:

• Total serum testosterone — measured on two separate occasions, ideally in the morning between 07:00 and 11:00, and ideally fasting. Testing should not be carried out during acute illness, as this can temporarily suppress levels. A diagnosis of testosterone deficiency should not be made on a single borderline result alone

• Luteinising hormone (LH) and follicle-stimulating hormone (FSH) — to help distinguish between primary (testicular) and secondary (pituitary/hypothalamic) hypogonadism

• Sex hormone-binding globulin (SHBG) — as this affects the amount of biologically active (free) testosterone; free testosterone or the free androgen index (FAI) may be calculated where SHBG is high or borderline results are obtained

• Full blood count, ferritin, and thyroid function tests — to exclude other common causes of hair loss such as iron deficiency and hypothyroidism

In the UK, a total testosterone level below approximately 12 nmol/L is commonly used as a threshold to prompt further investigation, though results must always be interpreted alongside symptoms and laboratory reference ranges, which can vary between assays.

For women presenting with diffuse hair loss alongside menstrual irregularities or signs of hyperandrogenism (such as acne or hirsutism), a broader hormonal profile may be appropriate. This can include total testosterone, SHBG, free androgen index, DHEAS, and prolactin, alongside consideration of PCOS — a common cause of androgen-related hair changes in women.

Referral pathways depend on the clinical picture: suspected hypogonadism is typically referred to endocrinology or andrology, whilst uncertain diagnoses, scarring alopecia, or hair loss refractory to initial treatment warrant referral to dermatology. NHS testing is available through your GP; private testing, whilst accessible, should always be interpreted within a full clinical context.

Treatment Options and What the Evidence Shows

TRT treats confirmed testosterone deficiency but is not a hair loss treatment and may worsen scalp thinning; minoxidil and finasteride are the evidence-based options for androgenetic alopecia.

Treatment for hair loss depends entirely on its underlying cause. Where investigations confirm genuine testosterone deficiency alongside significant symptoms, testosterone replacement therapy (TRT) may be considered. In the UK, TRT is available on the NHS in licensed forms, principally transdermal gels (such as Testogel or Tostran) and injectable preparations (such as Nebido [testosterone undecanoate] or Sustanon [mixed testosterone esters]). TRT is prescribed under specialist supervision in line with NICE, BSSM, and Society for Endocrinology guidance.

Patients considering TRT should be aware of the following:

• TRT is not a treatment for scalp hair loss. Because TRT increases circulating testosterone — some of which is converted to DHT — it may paradoxically worsen scalp hair thinning in individuals who are genetically predisposed to androgenetic alopecia

• TRT suppresses spermatogenesis and can significantly impair fertility; men wishing to father children should discuss this with their specialist before starting treatment

• Monitoring is essential and typically includes haematocrit and haemoglobin (to detect polycythaemia), PSA (in men over 40 or with prostate risk factors), lipids, blood pressure, and symptom review at regular intervals

• TRT is contraindicated in prostate or breast cancer, and cardiovascular risk should be reviewed before initiation

For androgenetic alopecia specifically, the evidence-based treatment options available in the UK include:

• Minoxidil (available over the counter as a topical solution or foam; see the EMC SmPC for full prescribing information) — licensed for both men and women; stimulates hair follicle activity, though the precise mechanism is not fully understood

• Finasteride 1 mg (prescription only, for men) — a 5-alpha reductase inhibitor that reduces DHT levels; supported by robust clinical trial evidence. Important safety information: the MHRA issued a Drug Safety Update in 2024 highlighting risks of depression, suicidal ideation, and persistent sexual dysfunction (including after stopping treatment). Patients should be screened for mood disorders before starting finasteride and monitored during treatment. A patient alert card should be provided. Women who are pregnant or may become pregnant must not handle crushed or broken finasteride tablets, as the active ingredient can be absorbed through the skin and may harm a male foetus. Any suspected side effects should be reported via the MHRA Yellow Card Scheme (available at yellowcard.mhra.gov.uk)

• Low-level laser therapy (LLLT) and platelet-rich plasma (PRP) — emerging treatments with a growing but still limited evidence base; neither is routinely commissioned on the NHS and both should be undertaken under specialist supervision

For hair loss related to nutritional deficiencies or thyroid dysfunction, treating the underlying condition is the primary intervention. Patients are encouraged to discuss all options with their GP or a dermatologist, as individual circumstances vary considerably and a personalised approach yields the best outcomes.

Frequently Asked Questions