Erectile dysfunction (ED) affects an estimated 30 million American men and becomes increasingly common with age, cardiovascular risk factors, and stress. This guide covers what causes ED, when to see a doctor, and how the four leading PDE5 inhibitors compare for treatment.
What causes ED?
ED is rarely a single-cause condition. Most cases combine physical and psychological factors:
- Vascular: atherosclerosis, high blood pressure, high cholesterol — reduce penile blood flow.
- Metabolic: type 2 diabetes and metabolic syndrome damage vascular and nerve function.
- Hormonal: low testosterone, thyroid disorders, elevated prolactin.
- Neurological: spinal injury, MS, Parkinson's, prostate surgery.
- Medication side effects: some SSRIs, beta blockers, and antihistamines.
- Psychological: anxiety, depression, relationship stress, performance anxiety.
When to see a doctor
ED can be an early warning sign of cardiovascular disease — sometimes appearing 3–5 years before a heart event. See a physician if ED is persistent, sudden-onset, or accompanied by chest discomfort, breathlessness, or leg pain.
The four PDE5 inhibitors compared
All four work by inhibiting phosphodiesterase-5, allowing nitric oxide signaling to relax penile smooth muscle. They differ in onset, duration, and food sensitivity.
- Sildenafil (Viagra / Cenforce): 30–60 min onset, 4–6 hr duration. Food-sensitive.
- Tadalafil (Cialis / Vidalista): 30–45 min onset, up to 36 hr duration. Not food-sensitive. Also used daily at low dose.
- Vardenafil (Levitra / Vilitra): 30 min onset, 4–5 hr. Similar profile to sildenafil.
- Avanafil (Stendra): 15–30 min onset, 6 hr. Fastest, fewest visual side effects.
Lifestyle interventions that improve ED
- Aerobic exercise 150 min/week — the single strongest lifestyle lever.
- Weight loss of 5–10% in men with BMI 30+.
- Smoking cessation.
- Sleep 7–9 hours (sleep apnea should be ruled out).
- Mediterranean-pattern diet.
Frequently asked questions
Can I combine PDE5 inhibitors with alcohol?
Small amounts are usually fine; large amounts blunt the effect and worsen orthostatic hypotension.
Are generics as effective as brand?
Yes — generic Sildenafil, Tadalafil and Vardenafil use the same active ingredients at bioequivalent dosages. See our Sildenafil vs Tadalafil guide.
Is ED reversible?
Frequently yes — especially when the underlying cause (metabolic syndrome, medication side effects, psychological stressors) is addressed.
This article is informational and not medical advice. Always consult a licensed prescriber. For bulk clinic sourcing of generic ED medications, contact our wholesale sourcing desk.