Erectile function and difficulties

The mechanism

Erection is a neurovascular event. Sexual stimulation triggers parasympathetic nitric oxide release; smooth muscle in the corpora cavernosa relaxes; arterial inflow increases; the expanding tissue compresses the veins against the tunica albuginea, trapping blood. Anything affecting nerves, arteries, hormones, smooth muscle or mood affects erections.

This is why erectile difficulty is rarely "all in the head" and rarely purely physical. Both routes are usually involved.

How common

The Massachusetts Male Aging Study (Feldman et al., 1994), following 1,290 men aged 40–70, found 52 percent reported some degree of erectile difficulty: 17 percent minimal, 25 percent moderate, 10 percent complete. Prevalence rises steeply with age but occasional difficulty occurs at every age and is not diagnostic of anything.

Erectile dysfunction is defined as persistent inability to achieve or maintain an erection sufficient for satisfactory sexual activity, generally for three months or more.

Erectile dysfunction is a cardiovascular warning sign

This is the most clinically important fact in the article. Penile arteries are narrower than coronary arteries, so atherosclerosis affects them first. Erectile dysfunction typically precedes a cardiac event by 3–5 years. Vlachopoulos et al.'s meta-analysis (2013) found ED associated with a 44 percent increase in cardiovascular events and a 25 percent increase in all-cause mortality.

New persistent erectile difficulty warrants a cardiovascular assessment: blood pressure, lipids, HbA1c, and a discussion of smoking and weight. The Princeton Consensus recommends this explicitly. A prescription without that assessment is incomplete care.

Causes worth investigating

Vascular: atherosclerosis, hypertension, diabetes, smoking, high cholesterol, obesity, sedentary lifestyle. Diabetes is the strongest single medical association.

Neurological: diabetic neuropathy, multiple sclerosis, Parkinson's, spinal cord injury, pelvic surgery — particularly radical prostatectomy — and pelvic radiotherapy.

Hormonal: hypogonadism, thyroid disease, hyperprolactinaemia. Testosterone should be measured on a morning sample and repeated before acting on it.

Medication: thiazide diuretics, beta blockers, SSRIs and SNRIs, antipsychotics, finasteride and dutasteride, anti-androgens, opioids, and heavy alcohol use.

Psychological: performance anxiety, depression, relationship distress, and spectatoring. A useful distinguishing sign: preserved morning and masturbatory erections with difficulty in partnered sex points toward a psychological or situational component; loss of all erections including nocturnal ones points toward an organic cause.

Treatments with evidence

Lifestyle. Not a consolation prize. Gupta et al.'s meta-analysis (2011, Archives of Internal Medicine) found lifestyle modification and cardiovascular risk factor treatment produced significant improvement in erectile function. Exercise in particular has consistent trial support; smoking cessation improves function over months.

PDE5 inhibitors — sildenafil, tadalafil, vardenafil, avanafil. Effective in roughly 60–70 percent of cases. They do not create an erection; they amplify the response to stimulation, which is the most common reason people conclude they have failed. Tadalafil's long half-life allows daily low-dose use, decoupling timing from planning. Absolutely contraindicated with nitrates — the combination causes profound hypotension. Caution with alpha blockers. Side effects: headache, flushing, nasal congestion, dyspepsia, transient visual changes.

Vacuum erection devices. Effective, non-pharmacological, particularly useful in penile rehabilitation after prostatectomy.

Intracavernosal alprostadil injection and intraurethral alprostadil. High efficacy, including where PDE5 inhibitors fail. Priapism is the main risk and requires emergency treatment within hours.

Penile prosthesis. Surgical, with the highest satisfaction rates of any treatment in long-term series, reserved for cases where other options fail.

Testosterone replacement only where hypogonadism is confirmed on repeated morning measurement with symptoms. It is not a treatment for erectile dysfunction with normal testosterone.

Psychosexual therapy, alone or alongside medication, has good evidence particularly where anxiety is prominent. Combined medical and psychological treatment outperforms either alone in several trials.

Low-intensity shockwave therapy has some supportive trial data but remains investigational; evidence quality is mixed and it is frequently sold well ahead of the evidence. Platelet-rich plasma injections have no adequate evidence and should be treated with scepticism.

Priapism

An erection lasting more than four hours without stimulation is a medical emergency. Ischaemic priapism causes permanent tissue damage and erectile dysfunction if untreated beyond roughly 24 hours. Attend an emergency department; do not wait it out.

Sources

• Feldman HA et al. "Impotence and its medical and psychosocial correlates: the Massachusetts Male Aging Study." Journal of Urology, 1994.
• Vlachopoulos CV et al. "Prediction of cardiovascular events and all-cause mortality with erectile dysfunction: a systematic review and meta-analysis." Circulation: Cardiovascular Quality and Outcomes, 2013.
• Nehra A et al. "The Princeton III Consensus recommendations for the management of erectile dysfunction and cardiovascular disease." Mayo Clinic Proceedings, 2012.
• Gupta BP et al. "The effect of lifestyle modification and cardiovascular risk factor reduction on erectile dysfunction: a systematic review and meta-analysis." Archives of Internal Medicine, 2011.
• European Association of Urology. Guidelines on sexual and reproductive health, current edition.
• Salonia A et al. EAU guidelines on male sexual dysfunction and priapism management.

Last reviewed: August 2026.