Whilst testosterone is widely recognised as the primary male sex hormone, oestrogen also plays an important role in men's sexual health. Men produce oestrogen through the conversion of testosterone, and maintaining appropriate levels is essential for various physiological functions, including libido, vascular health, and potentially erectile function. However, the relationship between low oestrogen and erectile dysfunction (ED) in men is complex and not fully understood. This article examines the current evidence on whether low oestrogen causes ED in men, explores how hormone imbalances affect erectile function, and outlines the diagnostic and treatment approaches recommended in UK clinical practice.

Understanding Estrogen's Role in Male Sexual Health

Whilst testosterone is widely recognised as the primary male sex hormone, oestrogen also plays a crucial role in men's health, including sexual function. Men produce oestrogen through the conversion of testosterone via an enzyme called aromatase, which is found in various tissues including adipose (fat) tissue, the brain, and the testes. Normal oestradiol levels in men typically range from approximately 40–160 pmol/L, though reference intervals are laboratory and assay-specific. These levels are significantly lower than in women but nonetheless essential for optimal physiological function.

Oestrogen in men contributes to several important processes that support sexual health. It helps regulate libido (sex drive), supports bone density, influences mood and cognitive function, and may play a role in vascular health. The endothelium—the inner lining of blood vessels—contains oestrogen receptors, though the clinical significance of this in erectile function remains an area of ongoing research. Erections depend fundamentally on adequate blood flow to the penile tissues, so factors affecting vascular health may influence erectile function.

The relationship between oestrogen and male sexual function is complex and involves a delicate balance. Both excessively high and abnormally low oestrogen levels can potentially disrupt sexual function. Research suggests that oestrogen receptors are present in penile tissue, indicating a possible direct role in erectile physiology. However, the precise mechanisms and clinical significance remain under investigation, with the balance between testosterone and oestrogen appearing more important than absolute oestrogen levels alone.

Does Low Estrogen in Men Cause Erectile Dysfunction?

The relationship between low oestrogen and erectile dysfunction (ED) in men is not straightforward, and there is no definitive consensus that low oestrogen alone directly causes ED. Current evidence suggests that whilst oestrogen plays a supportive role in male sexual function, it is the balance between testosterone and oestrogen—rather than isolated low oestrogen—that appears most clinically relevant.

Some research has indicated that men with very low oestrogen levels may experience reduced sexual desire and potentially erectile difficulties. Case reports involving men with oestrogen deficiency due to rare genetic conditions (aromatase deficiency) have shown that these individuals experienced improvements in sexual function when given oestrogen replacement. However, such cases are exceptionally rare, and most men with ED do not have clinically significant oestrogen deficiency.

More commonly, erectile dysfunction in men is associated with low testosterone levels (hypogonadism), which may secondarily affect oestrogen production since testosterone is converted to oestrogen. The majority of research and clinical focus has centred on testosterone's role in ED, as low testosterone is a well-established contributor to erectile problems, reduced libido, and other sexual difficulties.

It is important to note that excessively high oestrogen levels in men—often due to obesity, certain medications, or liver disease—are more frequently linked to sexual dysfunction than low levels. Elevated oestrogen can suppress testosterone production and contribute to ED.

ED often has vascular and psychological causes and may be an early marker of cardiovascular disease. Therefore, whilst there is limited evidence suggesting very low oestrogen may affect erectile function in rare cases, there is no established link indicating low oestrogen as a primary or common cause of ED in the general male population. The interplay of multiple hormones, vascular health, psychological factors, and underlying medical conditions typically determines erectile function.

How Hormone Imbalances Affect Erections in Men

Erectile function depends on a complex interplay of neurological, vascular, hormonal, and psychological factors. Hormonal imbalances can disrupt this delicate system in several ways, affecting both the physiological capacity for erections and sexual desire. Understanding these mechanisms helps clarify why hormone-related ED requires comprehensive assessment rather than focusing on a single hormone.

Testosterone plays the most prominent hormonal role in male sexual function. It influences libido, supports the production of nitric oxide (a key molecule for penile blood vessel dilation), and maintains the structural integrity of erectile tissue. Low testosterone can lead to reduced sexual desire, difficulty achieving or maintaining erections, and decreased spontaneous erections. Hypogonadism diagnosis requires compatible symptoms plus two early-morning total testosterone measurements below the laboratory reference range, with levels below 8 nmol/L generally considered low and 8-12 nmol/L borderline in UK practice.

When testosterone levels fall, oestrogen production may also decline since testosterone serves as the precursor for oestrogen synthesis. However, in some cases—particularly in men with obesity—testosterone may be low whilst oestrogen is elevated. Excess adipose tissue contains aromatase enzyme, which converts more testosterone to oestrogen, creating an unfavourable hormonal ratio. This imbalance can suppress the hypothalamic-pituitary-gonadal axis, further reducing testosterone production and contributing to ED.

Other hormones also influence erectile function. Prolactin, when elevated (hyperprolactinaemia), can suppress testosterone production and directly impair sexual function. Thyroid disorders, both hyperthyroidism and hypothyroidism, are associated with increased ED risk. Cortisol excess (Cushing's syndrome) can also contribute to sexual dysfunction. Certain medications, including some antidepressants, antihypertensives, and finasteride, may cause or worsen ED. The vascular effects of hormone imbalances are particularly important: adequate hormone levels support endothelial function and blood vessel health, which are essential for the haemodynamic changes required for erections. Chronic hormone imbalances may lead to structural changes in penile tissue, potentially making ED more difficult to reverse.

Diagnosing Low Estrogen and Erectile Problems

Diagnosing hormone-related erectile dysfunction requires a systematic approach that begins with a thorough clinical history and physical examination. When a man presents with ED, healthcare professionals should enquire about the onset, duration, and pattern of symptoms, as well as associated features such as reduced libido, morning erections, and general health status. A comprehensive medical history should identify cardiovascular risk factors, diabetes, medications, psychological stressors, and lifestyle factors including alcohol consumption and smoking.

According to NICE Clinical Knowledge Summary (CKS) guidance on erectile dysfunction assessment, initial investigations should include relevant blood tests to identify underlying causes. These typically comprise:

• Testosterone levels (measured in the morning between 8–10 am when levels peak)

• Sex hormone-binding globulin (SHBG) to calculate free testosterone if indicated

• Luteinising hormone (LH) and follicle-stimulating hormone (FSH) to assess pituitary function

• Prolactin if testosterone is low or symptoms suggest hyperprolactinaemia

• Fasting glucose and HbA1c to screen for diabetes

• Lipid profile to assess cardiovascular risk

• Thyroid function tests if clinically indicated

• Full blood count, renal and liver function tests where appropriate

Oestradiol levels are not routinely measured in men presenting with ED unless there are specific clinical indications, such as suspected aromatase excess, gynaecomastia (breast tissue enlargement), or when investigating unexplained hypogonadism. If required, sensitive assays (such as liquid chromatography-mass spectrometry) may be needed for accurate measurement of the lower levels found in men.

If initial tests reveal low testosterone, repeat testing is essential as levels can fluctuate. Two early-morning samples showing low testosterone with compatible symptoms confirm hypogonadism, with free testosterone calculation recommended when SHBG is abnormal. Cardiovascular risk assessment should be performed, as ED may be an early marker of cardiovascular disease. Further investigations may include pituitary imaging if secondary hypogonadism is suspected, or referral to endocrinology for complex cases. Patients should be advised to consult their GP if they experience persistent erectile difficulties, reduced sexual desire, or other symptoms of hormone imbalance such as fatigue, mood changes, or reduced muscle mass. Early assessment allows identification of treatable causes and underlying health conditions that may require intervention.

Treatment Options for Hormone-Related Erectile Dysfunction

Treatment for hormone-related erectile dysfunction should be tailored to the underlying cause and individual patient circumstances. When low testosterone is confirmed as a contributing factor, testosterone replacement therapy (TRT) may be appropriate for men with symptomatic hypogonadism. TRT is available in various formulations including transdermal gels and intramuscular injections (testosterone undecanoate or enanthate). According to UK guidelines, TRT should only be initiated after two confirmatory low testosterone readings and appropriate patient counselling about benefits and risks.

Testosterone replacement can improve libido and may enhance erectile function in men with hypogonadism, though the effect on erections is often modest and variable. Some men may require additional ED-specific treatments. Phosphodiesterase type 5 (PDE5) inhibitors—such as sildenafil, tadalafil, and vardenafil—remain first-line pharmacological treatment for ED regardless of hormonal status. These medications enhance the erectile response to sexual stimulation by increasing blood flow to the penis and can be used alongside TRT when appropriate. PDE5 inhibitors are contraindicated in patients taking nitrates or riociguat due to potentially dangerous drops in blood pressure, and caution is needed in certain cardiovascular conditions.

For the rare cases of confirmed oestrogen deficiency in men, specialist endocrinology input is essential. Treatment approaches are not standardised and must be individualised. In cases where elevated oestrogen contributes to ED (such as in obesity), addressing the underlying cause through weight loss, lifestyle modification, and management of contributing conditions is paramount. Aromatase inhibitors, which reduce oestrogen production, are occasionally used in specialist settings but are not routinely recommended and require careful monitoring.

Lifestyle interventions form a crucial component of treatment for hormone-related ED. These include:

• Weight loss in overweight or obese men (can improve testosterone levels and reduce excess oestrogen)

• Regular physical exercise (enhances cardiovascular health and hormone balance)

• Smoking cessation (improves vascular function)

• Alcohol moderation (excessive alcohol affects hormone production and erectile function)

• Stress management and adequate sleep (support healthy hormone regulation)

Patients should be monitored regularly during treatment. For those on TRT, follow-up includes checking testosterone levels, haematocrit (with action if >54%), prostate-specific antigen (PSA), and symptom response. TRT is contraindicated in men with prostate or breast cancer and requires baseline PSA and digital rectal examination as indicated by age and risk factors. Men should be advised that TRT suppresses spermatogenesis and should be avoided if trying to conceive; specialist referral for alternative treatments may be needed. Patients should report any suspected side effects via the MHRA Yellow Card Scheme and seek medical attention if they experience chest pain, breathing difficulties, leg swelling, or prolonged erections (priapism). Referral to specialist services is appropriate for complex cases, treatment-resistant ED, or when underlying endocrine disorders require expert management. A multidisciplinary approach involving GPs, urologists, and endocrinologists ensures comprehensive care for men with hormone-related erectile dysfunction.

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