Male Sexual Health: Erectile Dysfunction, Ejaculatory Disorders, and STI Prevention

Introduction

Male sexual health encompasses erectile function, ejaculatory control, libido, and prevention of sexually transmitted infections. Sexual dysfunction increases with age but is not a normal consequence of aging. Underlying medical conditions, medications, and psychological factors all contribute. Sexual health is an important component of overall health and quality of life.

Erectile Dysfunction (ED)

Definition and Prevalence

Aspect	Detail
Definition	Inability to achieve or maintain an erection sufficient for satisfactory sexual performance for 3+ months
Prevalence	40% of men at age 40; 70% at age 70
Complete ED (no erections)	5% at 40; 15% at 70
Underreported	Estimated that 50-70% of men with ED do not seek treatment

Pathophysiology of Erection

Phase	Mechanism
Stimulation	Sexual stimulation (visual, tactile, mental) activates parasympathetic nerves (S2-S4)
Nitric oxide release	NANC neurons release NO, endothelial cells release NO
cGMP cascade	NO activates guanylate cyclase, producing cGMP
Smooth muscle relaxation	cGMP relaxes corpus cavernosum smooth muscle
Increased blood flow	Relaxation allows blood to fill corporal sinuses
Veno-occlusion	Expanding sinusoids compress subtunical venules against tunica albuginea (traps blood)
Detumescence	cGMP hydrolyzed by PDE5; sympathetic tone returns; smooth muscle contracts

Etiology: Organic vs Psychogenic

Feature	Organic	Psychogenic
Onset	Gradual, progressive	Sudden (situational)
Quality of erections	Poor erections at all times (morning, masturbation, partner)	Morning erections present (nocturnal tumescence intact); good erections with masturbation
Situational variation	Consistent across situations	Variable by partner/situation
Risk factors present	Yes (vascular, neurologic, endocrine medications)	Often absent
Age association	Increases with age	Any age
Laboratory abnormalities	May be present	Usually normal
Percentage of cases	70-80% (mixed)	10-20% (pure)

Organic Causes

Category	Condition	Mechanism
Vascular	Atherosclerosis, hypertension, hyperlipidemia, diabetes, smoking	Reduced arterial inflow; venous leak (damaged veno-occlusive mechanism)
Neurologic	Spinal cord injury, multiple sclerosis, peripheral neuropathy (diabetic), Parkinson disease, stroke	Disrupted nerve signal to corpora cavernosa
Endocrine	Hypogonadism, hyperprolactinemia, hyperthyroidism/hypothyroidism, Cushing	Low testosterone reduces NO synthase; prolactin inhibits gonadotropins
Medications	Antihypertensives (beta-blockers, thiazides), SSRIs, antipsychotics, antiandrogens, digoxin, H2 blockers	Central or peripheral effects on erectile mechanism
Structural	Peyronie disease, penile fracture, priapism scarring	Mechanical inability to maintain erection
Lifestyle	Smoking, obesity, alcohol (>3 daily), sedentary lifestyle, sleep apnea	Vascular damage, hormonal changes, endothelial dysfunction
Iatrogenic	Post-radical prostatectomy (nerve-sparing vs non-sparing), pelvic radiation, TURP	Nerve or vascular damage

Evaluation

Test	Purpose	When Indicated
History and IIEF (International Index of Erectile Function)	Assess severity, onset, situational factors, risk factors, psychosocial	All patients
Physical exam	Testicular size, penile plaques, prostate exam, peripheral pulses, neurologic exam	All patients
Morning erections (nocturnal penile tumescence)	Differentiates organic vs psychogenic	First diagnostic step
Fasting glucose / A1c	Diabetes screening	Most patients
Lipid panel	Hyperlipidemia	Most patients
Morning total testosterone (x2)	Hypogonadism screen	All patients (especially if decreased libido)
Prolactin	Hyperprolactinemia	If low testosterone or gynecomastia
TSH	Thyroid dysfunction	If symptoms
Intracavernosal injection test	Pharmaco-cavernosometry/ultrasonography	For complex cases; evaluates vascular function
Penile duplex ultrasound	Evaluate arterial inflow and venous occlusion	Pre-operative (before bypass/ligation)
Nocturnal penile tumescence (RigiScan)	Objective overnight assessment	Medico-legal, differentiating organic from psychogenic

Treatment

Step	Treatment	Details	Efficacy
1	Lifestyle modification	Weight loss, exercise (40 min/day), smoking cessation, limit alcohol, treat sleep apnea	30-50% improvement in mild ED
2	Address underlying condition	Optimize diabetes, hypertension, lipids; replace testosterone (if hypogonadism); change offending medication	Variable
3	PDE5 inhibitors (oral)	See below	60-80%
4	Second-line: intraurethral/intracavernosal	Alprostadil (urethral suppository or intracavernosal injection); combination therapy (bimix, trimix)	70-85%
5	Mechanical: vacuum erection device (VED)	Negative pressure device; constriction ring at base	70-80%
6	Surgical: penile prosthesis	Inflatable (3-piece) or malleable (semi-rigid)	>95% satisfaction

PDE5 Inhibitors

Drug	Onset	Duration	Effect of Food	Dosing Flexibility	Side Effects
Sildenafil (Viagra)	30-60 min	4-6 hours	High-fat meal delays absorption	25, 50, 100 mg	Flushing (10%), headache (16%), dyspepsia (7%), nasal congestion (4%), blue vision (3%)
Tadalafil (Cialis)	30-60 min (PRN); 2-3 days (daily)	24-36 hours (PRN); continuous (daily)	Not affected	5 mg daily; 10, 20 mg PRN	Headache, dyspepsia, back pain/myalgia (7%), nasal congestion
Vardenafil (Levitra, Staxyn)	30-60 min	4-6 hours	Moderate-fat meal delays	5, 10, 20 mg	Similar to sildenafil; less vision change
Avanafil (Stendra)	15-30 min	4-6 hours	Not significantly affected	50, 100, 200 mg	Similar to others; fewer side effects per dose

PDE5i Contraindications

Absolute	Relative
Nitrate use (any form: nitro, isosorbide, nitroglycerin) - can cause profound hypotension	Alpha-blocker use (especially tamsulosin) - use lowest ED dose
Cardiovascular: recent MI (<3 months), unstable angina, uncontrolled HTN, severe hypotension	Severe hepatic impairment
Severe renal impairment (CrCl <30)	Bleeding disorder / active peptic ulcer
Hereditary degenerative retinal disorders (retinitis pigmentosa)	Anatomic penile deformity (Peyronie, cavernosal fibrosis)
	Priapism risk (sickle cell, multiple myeloma, leukemia)

Testosterone Replacement Therapy (TRT) for ED

Aspect	Detail
Indication	ED + documented low testosterone (total T <300 ng/mL, ideally with free T) + symptoms
Response	40-60% improvement in erectile function; may take 3-6 months
Combination	Add PDE5i if inadequate (synergistic)
Contraindications	PSA >4 ng/mL, palpable prostate nodule, breast cancer, erythrocytosis, untreated severe sleep apnea

Premature Ejaculation (PE)

Definition

Criteria	Detail
Intravaginal ejaculatory latency time (IELT)	<1 minute (lifelong) or <3 minutes (acquired)
Control	Perceived lack of control over ejaculation
Distress	Negative personal consequences (distress, bother, frustration, avoidance)
Lifelong PE	Present from first sexual experiences
Acquired PE	Began at some point after prior normal function

Causes

Type	Causes
Lifelong (primary)	Genetic predisposition (5-HT receptor polymorphism), neurobiological (low serotonergic activity)
Acquired (secondary)	ED (most common cause - hurry before losing erection), prostatitis/CPPS, hypothyroidism, anxiety, depression, relationship issues

Treatment

Treatment	Dose	Efficacy	Mechanism
Dapoxetine (PO, not available in US)	30-60 mg 1-2 hours before sex	3-4x increase in IELT	Short-acting SSRI; delays ejaculation
Paroxetine (off-label)	10-40 mg daily or 20 mg 3-6 hours before sex	6-8x increase in IELT (daily); 3-5x (on-demand)	SSRI; longest half-life
Sertraline (off-label)	50-200 mg daily	3-4x increase	SSRI
Fluoxetine (off-label)	20-40 mg daily	3-4x increase	SSRI
Clomipramine (off-label)	25-50 mg daily or 25 mg 4-6 hours before sex	3-5x increase	Tricyclic antidepressant
Topical lidocaine/prilocaine (EMLA)	Apply 20-30 min before sex	5-8x increase in IELT	Topical anesthetic; reduces penile sensitivity
Topical lidocaine spray	3 sprays to glans 5 min before sex	5-6x increase	Same
Behavioral (stop-start, squeeze technique)	Integrated into sexual activity	Variable (requires partner cooperation)	Learn to recognize pre-ejaculatory sensations

Libido (Male Hypoactive Sexual Desire Disorder)

Aspect	Detail
Definition	Persistently or recurrently deficient or absent sexual fantasies and desire for sexual activity, causing personal distress
Prevalence	5-15% of men
Causes	Low testosterone, hyperprolactinemia, depression, medications (SSRIs, opioids), chronic illness, relationship issues, stress, fatigue
Combined with ED	30-40% of men with ED also have low desire

STI Prevention

Common STIs in Men

STI	Pathogen	Symptoms	Treatment
Chlamydia	Chlamydia trachomatis	Urethritis (dysuria, discharge); often asymptomatic (30-50%)	Azithromycin 1 g PO single dose or doxycycline 100 mg BID x7d
Gonorrhea	Neisseria gonorrhoeae	Urethritis (purulent discharge, dysuria); rectal, pharyngeal	Ceftriaxone 500 mg IM + azithromycin 1 g PO (or doxycycline if concern)
Syphilis	Treponema pallidum	Primary: painless chancre; Secondary: rash, fever, lymphadenopathy; Tertiary: neurologic, cardiac	Penicillin G benzathine 2.4 million units IM x1 (primary/secondary); 3 doses for late
HIV	HIV-1 (HIV-2 rare)	Acute: flu-like illness; chronic: may be asymptomatic for years; AIDS: opportunistic infections	Antiretroviral therapy
HSV-2 (genital herpes)	Herpes simplex virus type 2	Painful vesicular lesions; recurrent outbreaks; can shed virus without lesions	Acyclovir, valacyclovir, famciclovir (first episode or suppressive)
HPV (genital warts)	Human papillomavirus (types 6, 11)	Painless warts (condylomata acuminata)	Cryotherapy, topical imiquimod, podophyllotoxin, surgical excision
Trichomoniasis	Trichomonas vaginalis	Urethritis (dysuria, discharge); often asymptomatic (50-70%)	Metronidazole 2 g PO single dose
Mycoplasma genitalium	Mycoplasma genitalium	Urethritis; persistent/recurrent after treatment of chlamydia/gonorrhea	Azithromycin 1 g (first-line, but resistance increasing); moxifloxacin 400 mg x7-14d

Prevention Strategies

Strategy	Efficacy	Recommendation
Male condoms (latex/polyurethane)	98% effective with perfect use; 85% typical; 70% for herpes/HPV/syphilis	Consistent and correct use every time
Pre-exposure prophylaxis (PrEP) for HIV	>99% reduction in HIV acquisition with daily dosing (95% with on-demand for MSM)	Consider for sexually active men with multiple partners, MSM, serodiscordant relationships
Post-exposure prophylaxis (PEP) for HIV	>80% effective (start within 72 hours of exposure)	Emergency department for high-risk exposure
HPV vaccine (Gardasil 9)	>90% against vaccine-type HPV and genital warts	Routine vaccination at age 11-12; catch-up through 26 years
Hepatitis B vaccine	>95% seroprotection	Routine; recommended for MSM, multiple partners
Hepatitis A vaccine	>95% seroprotection	Recommended for MSM
HIV testing	All men at least once; annually or q3 months if high risk	CDC guidelines
Regular STI testing	Asymptomatic screening for MSM: q3-12 months depending on risk	CDC guidelines
Mutual monogamy	Protective with testing	After confirmatory testing
Circumcision	50-60% reduction in female-to-male HIV transmission (African studies)	Individual decision

STI Screening Recommendations (CDC)

Population	Chlamydia/Gonorrhea	Syphilis	HIV	Hepatitis C
Sexually active men <25	Annually	Not routine	At least once	One-time
MSM	At least annually (q3-6 mo if high risk)	Annually (q3-6 mo if high risk)	Annually (q3-6 mo if high risk)	Annually
HIV-positive MSM	At each visit	At each visit	N/A	At baseline, then annually
Men with multiple partners	Annually	Annually	Annually	One-time
Pre-exposure prophylaxis (PrEP) users	q3-6 months	q3-6 months	q3 months	Annually