Erectile dysfunction: evidence-based causes, vascular mechanisms, diagnostic workup, and modern treatment options

Erectile dysfunction (ED) is the persistent or recurrent inability to achieve and/or maintain an erection sufficient for satisfactory sexual performance. It is common, multifactorial, and frequently signals underlying systemic disease. Clinically, ED is not merely a quality-of-life issue; it can reflect vascular endothelial dysfunction, impaired nitric oxide (NO) signaling, neuropathic pathology, hormonal imbalance, medication effects, or psychological factors.

Pathophysiologically, erection depends on coordinated arterial inflow, venous occlusion, smooth muscle relaxation, intact neural pathways, and adequate endocrine function. Sexual stimulation triggers parasympathetic activation, increasing NO release and cyclic guanosine monophosphate (cGMP) in cavernosal smooth muscle. This promotes relaxation, arterial dilation, and increased intracavernosal pressure. Effective veno-occlusion then traps blood within the corpora cavernosa, sustaining rigidity. ED arises when any step fails—e.g., atherosclerotic narrowing reduces inflow, diabetes damages autonomic nerves, and hypogonadism diminishes libido and erectile responsiveness.

Vascular disease is among the most important organic causes. Atherosclerosis, hypertension, dyslipidemia, smoking, obesity, and metabolic syndrome impair endothelial function, reducing NO bioavailability. ED can precede overt coronary artery disease and therefore serves as an early marker of cardiovascular risk. Neurogenic etiologies include diabetic peripheral/autonomic neuropathy, spinal cord injury, multiple sclerosis, and after pelvic surgery or radiation. Endocrine causes include low testosterone, hyperprolactinemia, and thyroid dysfunction. Medication-related ED is also common; drugs that affect vascular tone, neurotransmission, or hormones include certain antihypertensives (particularly nonselective beta-blockers and thiazides), antidepressants (especially selective serotonin reuptake inhibitors), antipsychotics, finasteride, opioids, and some agents for prostate disease.

Psychogenic ED may coexist with organic disease. Performance anxiety, maladaptive beliefs, depression, relationship stress, and sleep disruption can impair arousal pathways and increase sympathetic tone, counteracting erection physiology. Importantly, mixed etiologies are typical; organic impairment can prime anxiety and avoidance cycles, further worsening outcomes. Assessment should therefore integrate both physical and psychological contributors rather than treating ED as purely behavioral.

Evaluation begins with a detailed sexual and medical history: onset (sudden vs gradual), situational vs consistent dysfunction, nocturnal/morning erections, medications, comorbidities (diabetes, cardiovascular disease, kidney disease), smoking and alcohol use, neurologic symptoms, and endocrine signs. Physical examination should include general health metrics (blood pressure, BMI, waist circumference), cardiovascular and genitourinary evaluation, and focused neurologic assessment when indicated.

Laboratory testing is individualized but commonly includes fasting glucose or HbA1c, lipid profile, serum creatinine, total testosterone (ideally in the morning with repeat confirmation if low), and additional studies guided by symptoms such as prolactin or thyroid-stimulating hormone. If there is concern for vascular or hormonal pathology, referral to urology and consideration of specialized testing may follow. Imaging or functional studies are reserved for complex or treatment-refractory cases.

First-line management for most patients is lifestyle optimization and targeted risk-factor control: weight reduction, regular aerobic and resistance exercise, smoking cessation, improved glycemic control, blood pressure management, and moderation of alcohol. These interventions improve endothelial function and can enhance treatment responsiveness.

Pharmacologic therapy with phosphodiesterase type 5 (PDE5) inhibitors—such as sildenafil, tadalafil, vardenafil, and avanafil—enhances the NO–cGMP pathway and improves erections in response to sexual stimulation. Selection depends on comorbidities, drug interactions, dosing convenience, and onset/duration preferences. A critical safety point is the absolute contraindication of PDE5 inhibitors with nitrates (e.g., nitroglycerin) due to risk of profound hypotension. Caution is also required with certain alpha-blockers and significant cardiovascular instability.

If PDE5 inhibitors are ineffective or contraindicated, alternatives include vacuum erection devices, intracavernosal injections (e.g., alprostadil), intraurethral alprostadil, and for selected patients, combination regimens under specialist guidance. For men with refractory ED or unfavorable pharmacologic response, penile prosthesis implantation offers high satisfaction rates. Psychosexual interventions—such as cognitive-behavioral therapy, performance anxiety reduction, and couple-based strategies—are essential when psychological drivers are prominent.

Because ED may reflect systemic vascular and metabolic disease, clinicians should screen for cardiovascular risk and coordinate care with primary care and cardiology when appropriate. Prognosis improves with early identification and treatment of reversible causes, adherence to lifestyle changes, and careful selection of therapies. Source: [@ifly93/Jun 13, 2026]