Erectile Dysfunction: A Doctor's Guide for 2026

What Is Erectile Dysfunction?

Erectile dysfunction is the consistent inability to achieve or maintain an erection firm enough for satisfactory sexual activity. A single episode does not meet the diagnostic threshold. The standard clinical definition requires symptoms present for at least 3 months, per the AUA/SMSNA guidelines on sexual dysfunction [1].

How Common Is ED?

The Massachusetts Male Aging Study found that 52% of men between ages 40 and 70 reported some degree of erectile difficulty, with complete ED affecting 10% of that group [2]. Prevalence rises steeply with age: roughly 5-10% of men in their 40s versus 40-70% of men over 70 experience clinically significant ED [3].

The Physiology Behind an Erection

An erection depends on nitric oxide (NO) release from cavernous nerve endings and endothelial cells. NO activates guanylate cyclase, raising cyclic GMP (cGMP), which relaxes smooth muscle in the corpora cavernosa. Blood fills the sinusoidal spaces. Phosphodiesterase type 5 (PDE5) degrades cGMP and ends the erection. PDE5 inhibitors block that degradation, prolonging smooth-muscle relaxation [4].

Vascular, neurogenic, hormonal, and psychogenic factors can each disrupt this cascade. Most ED in men over 50 has a vascular component, often reflecting the same endothelial dysfunction driving coronary artery disease [5].

Conditions That Raise ED Risk

• Type 2 diabetes (3-fold increased risk, affecting up to 75% of diabetic men over 20 years of disease) [6]
• Cardiovascular disease and hypertension
• Obesity and metabolic syndrome
• Hypogonadism (low testosterone)
• Depression and anxiety
• Medications: SSRIs, beta-blockers, thiazide diuretics, anti-androgens

Diagnosing ED: What a Workup Looks Like

A proper ED workup covers more than a symptom check. The AUA guideline (2018, amended 2024) specifies a minimum evaluation that includes a focused sexual, medical, and psychosocial history; a physical exam; and a targeted lab panel [1].

Validated Questionnaires

The International Index of Erectile Function (IIEF-5), also called the Sexual Health Inventory for Men (SHIM), is a 5-item validated tool scored 1-25. Scores of 22-25 indicate no ED; 17-21, mild ED; 12-16, mild-to-moderate; 8-11, moderate; 5-7, severe [7].

Lab Tests to Order at Baseline

| Test | Why It Matters | |------|---------------| | Morning total testosterone | Screens for hypogonadism | | Fasting glucose / HbA1c | Identifies undiagnosed type 2 diabetes | | Lipid panel | Quantifies cardiovascular risk | | TSH | Rules out thyroid dysfunction | | Prolactin | If testosterone is low or libido is absent |

A low morning testosterone (generally <300 ng/dL on two fasting measurements) warrants testosterone replacement before or alongside PDE5 inhibitor therapy [8].

Cardiovascular Risk Stratification

The Princeton Consensus III Conference stratified men with ED into three cardiovascular risk categories [9]:

• Low risk: Controlled hypertension, mild stable angina, no symptoms after moderate exertion. Sexual activity and ED treatment are safe.
• Intermediate risk: Moderate stable angina, recent MI (2-6 weeks), non-cardiac sequelae of atherosclerosis. Requires cardiac stress testing before proceeding.
• High risk: Unstable angina, severe heart failure, recent MI (<2 weeks), uncontrolled arrhythmias. Defer sexual activity and ED treatment until cardiac condition is stabilized.

First-Line Treatment: PDE5 Inhibitors

PDE5 inhibitors are the recommended first-line pharmacological therapy for most men with ED, regardless of cause, per the AUA and the European Association of Urology (EAU) [1]. Four agents hold FDA approval: sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra), and avanafil (Stendra) [10].

Head-to-Head Comparison of the Four PDE5 Inhibitors

| Drug | Approved Doses | Onset | Duration | Food Effect | Half-life | |------|---------------|-------|----------|-------------|-----------| | Sildenafil | 25, 50, 100 mg on-demand | 30-60 min | 4-6 h | High-fat meal delays absorption | 3-5 h | | Tadalafil | 10, 20 mg on-demand; 2.5, 5 mg daily | 30-45 min | Up to 36 h | None | 17.5 h | | Vardenafil | 5, 10, 20 mg on-demand | 25-60 min | 4-6 h | High-fat meal delays absorption | 4-5 h | | Avanafil | 50, 100, 200 mg on-demand | 15-30 min | 6-12 h | Minimal | 3-5 h |

A 2013 Cochrane meta-analysis of 130 randomized trials (N>17,000) found all four agents significantly improved erectile function scores versus placebo, with odds ratios for successful intercourse ranging from 3.5 to 8.0 depending on the molecule and dose [11].

Sildenafil: The Reference Standard

Sildenafil was the first oral ED therapy approved by the FDA in March 1998 [10]. In the key Phase III trials, 69% of all attempts at intercourse were successful in men taking sildenafil 50-100 mg versus 22% on placebo [12]. The 50 mg dose is a reasonable starting point; dose can be halved for men over 65 or those on alpha-blockers.

Tadalafil: On-Demand or Daily

Tadalafil's 17.5-hour half-life allows either on-demand dosing (10-20 mg taken before activity) or a once-daily regimen at 2.5-5 mg. The daily option removes the need to time the dose relative to sex. A network meta-analysis published in the European Urology found tadalafil on-demand numerically superior to sildenafil on the IIEF erectile function domain score (mean difference 1.4 points), though the clinical significance of this difference remains debated [13].

Avanafil: Fastest Clinical Onset

Avanafil 100 mg can produce an erection adequate for intercourse within 15 minutes in some men. In the REVIVE trial (N=440), 57% of avanafil 200 mg attempts succeeded at 15 minutes post-dose, versus 27% on placebo [14]. Its higher PDE5 selectivity compared with sildenafil produces fewer visual side effects.

Common Side Effects and Absolute Contraindications

All PDE5 inhibitors share a class-wide contraindication with nitrates (including nitroglycerin, isosorbide mono/dinitrate, and recreational nitrite "poppers"). Co-administration can cause severe, potentially fatal hypotension [15]. Other contraindications include:

• Recent stroke or MI (<90 days for most agents)
• Severe hepatic impairment
• Concomitant use of riociguat or soluble guanylate cyclase stimulators
• Hypotension (resting BP <90/50 mmHg)

Common side effects: headache (10-16%), flushing (5-12%), nasal congestion, dyspepsia. Sildenafil and vardenafil may cause transient blue-green visual tint due to partial PDE6 inhibition.

Lifestyle Interventions: Evidence and Targets

Lifestyle changes are not optional add-ons. They address root causes and can restore erectile function without medication.

Weight Loss

A landmark RCT published in JAMA (N=110 obese men, BMI >30) found that a 2-year supervised weight-loss program restoring a mean 14 kg loss improved IIEF scores by 6.9 points and restored normal erectile function in 31% of participants, versus 5% in the control group (P<0.001) [16]. The mechanism involves reduced inflammatory cytokines, improved endothelial NO production, and rising testosterone.

Exercise

A meta-analysis in Sexual Medicine Reviews (2018, 10 studies, N=1,000+) found that aerobic exercise at moderate-to-vigorous intensity (40 minutes, 4 days per week) improved IIEF scores by a mean of 3.85 points [17]. This effect was most pronounced in men with cardiovascular disease, metabolic syndrome, or hypertension.

Smoking Cessation and Alcohol

Current smoking doubles ED risk. One study of 4,764 men found that quitting smoking for 1 year improved erection quality in 25% of those who had smoked >20 cigarettes per day [18]. Heavy alcohol use (more than 14 drinks per week) suppresses testosterone and impairs neural signaling; reducing intake to moderate levels may improve function within 3-6 months.

Second-Line Therapies

When PDE5 inhibitors fail or are contraindicated, several second-line options are available.

Testosterone Replacement Therapy (TRT)

In men with confirmed hypogonadism (total testosterone <300 ng/dL on two measurements), TRT alone improves IIEF scores. A 2016 placebo-controlled trial (TRAVERSE precursor study, N=470) showed testosterone gel (1%, 50-100 mg/day) raised IIEF-EF domain scores by 2.3 points over 6 months [19]. Combining TRT with a PDE5 inhibitor in hypogonadal men produces additive benefit compared with either agent alone [20].

Vacuum Erection Devices (VED)

VEDs are mechanical, drug-free, and FDA-cleared. A pump creates negative pressure around the penis, drawing blood into the corpora. A constriction ring maintains the erection. Satisfaction rates of 68-83% have been reported in older men or those with contraindications to oral therapy [21]. VEDs are particularly useful post-radical prostatectomy during penile rehabilitation.

Intraurethral Alprostadil (MUSE)

Alprostadil (prostaglandin E1) delivered as a urethral suppository (MUSE, 125-1000 mcg) produces erections in 43-65% of men in clinical trials [22]. Penile pain is the most common complaint, reported in up to 36% of users.

Intracavernosal Injections (ICI)

Self-injection of alprostadil (Caverject, 5-40 mcg) directly into the corpus cavernosum produces erections in 70-90% of men, including those who do not respond to oral therapy [23]. The Tri-Mix formulation (alprostadil, phentolamine, papaverine) extends efficacy further. Priapism is the main serious risk; men must be counseled to seek emergency care for erections lasting >4 hours.

Low-Intensity Shockwave Therapy (LiSWT)

LiSWT uses acoustic waves to stimulate penile neovascularization and NO release. A 2019 meta-analysis of 14 RCTs (N=833) found LiSWT improved IIEF scores by a mean of 3.58 points over sham, with the strongest effects in vasculogenic ED [24]. The AUA currently classifies LiSWT as investigational for ED outside a clinical trial context, citing heterogeneity in protocols [1]. HealthRX providers discuss this option in the context of its current evidence limitations.

Third-Line and Surgical Options

Penile Prosthesis

Inflatable penile prosthesis (IPP) implantation is the definitive surgical option for men who have failed or cannot tolerate medical and mechanical therapies. Three-piece IPP devices (AMS 700, Coloplast Titan) produce rigidity on demand via a scrotal pump. Patient satisfaction rates exceed 90% at 5 years in published series [25]. Infection is the primary risk (1-3% in modern series with antibiotic-impregnated devices).

Vascular Surgery

Penile arterial reconstruction is reserved for young men (<45 years) with focal arterial occlusion from pelvic trauma and no systemic atherosclerosis. The number of appropriate candidates is small; AUA guidelines do not recommend penile venous surgery for most men [1].

ED in Special Populations

Men With Type 2 Diabetes

Diabetic men respond to PDE5 inhibitors, though response rates are modestly lower than in the general population. A pooled analysis of 12 trials found sildenafil effective in 63% of diabetic men versus 83% in non-diabetic controls [26]. Optimizing glycemic control (target HbA1c <7%) is part of ED management in this group.

Post-Prostatectomy ED

Radical prostatectomy causes cavernous nerve injury. Early penile rehabilitation (PDE5 inhibitor nightly or VED use within 4-6 weeks post-surgery) appears to speed recovery of spontaneous erections, though long-term RCT evidence remains limited [27]. Nerve-sparing surgery is associated with 40-70% return of erections at 2 years, depending on patient age and nerve preservation quality.

ED and Cardiovascular Disease

ED is now recognized as an independent cardiovascular risk marker. A 2011 meta-analysis in Archives of Internal Medicine (14 studies, N=92,757) found men with ED had a 44% higher relative risk of cardiovascular events (HR 1.44, 95% CI 1.27-1.63) [28]. Clinicians should screen men with new-onset ED for undiagnosed cardiovascular risk factors.

Psychogenic ED

Pure psychogenic ED accounts for roughly 10-20% of cases, most commonly in men under 40. Sex therapy, cognitive behavioral therapy (CBT), and couples counseling are first-line approaches; PDE5 inhibitors may serve as a short-term adjunct to break the performance anxiety cycle. A systematic review in Journal of Sexual Medicine (2020) found CBT plus sildenafil superior to either treatment alone in men with mixed psychogenic and organic ED [29].

Monitoring and Follow-Up

After initiating therapy, the AUA recommends follow-up at 4-6 weeks for response assessment using the IIEF-5 and to screen for side effects [1]. Men on daily tadalafil should have blood pressure and cardiovascular status reviewed at 3 months. Testosterone levels should be re-checked 3 months after starting TRT. Men on intracavernosal injections require annual review and priapism counseling at each visit.

If a patient has not responded to an adequate trial of two different PDE5 inhibitors (correct dose, correct timing, at least 6 attempts per agent), referral to urology is appropriate.

When to Refer

• Absence of morning erections or libido suggests hypogonadism or neurogenic cause: refer to endocrinology or urology.
• Penile curvature with ED: evaluate for Peyronie's disease before recommending implant.
• Failure of second-line therapies: urology for prosthesis discussion.
• Young men with new-onset ED and no obvious risk factors: consider vascular workup.