Erectile Dysfunction: Causes & Treatments

Medically reviewed by our clinical team | Last reviewed: April 22, 2026
This guide is for educational purposes only and is not a substitute for personalized medical advice. Erectile dysfunction can be a sign of underlying cardiovascular or hormonal disease — please consult a qualified clinician for evaluation.

Erectile dysfunction (ED) is one of the most common — and least talked about — health concerns men face. By age 40, roughly 40 percent of men have experienced it. By 70, that number climbs to about 70 percent. And yet most men either ignore it, self-medicate with online pills of unknown origin, or assume it is “just part of getting older.”

Here is what most guys are not told: ED is rarely just a sexual issue. It is often the first visible symptom of something deeper — vascular disease, hormonal imbalance, sleep dysfunction, medication side effects, mental health issues, or a combination. Treating the symptom without finding the cause leaves the underlying problem to keep doing damage.

This guide walks through what causes ED, how it should be evaluated, what treatments actually work, and what to do if pills are not enough.

What is erectile dysfunction?

ED is the consistent inability to achieve or maintain an erection sufficient for satisfying sexual activity. The key words are consistent and satisfying. Occasional difficulty — after a stressful day, too much alcohol, or with a new partner — is normal and not ED. A pattern that persists for several weeks or months, or that begins to affect your relationship and confidence, is worth evaluating.

Erections are a vascular event. Sexual stimulation triggers a nervous-system signal that releases nitric oxide, which relaxes the smooth muscle in penile arteries. Blood rushes in, the corpora cavernosa expand, and outflow veins are compressed — trapping the blood and producing rigidity. If anything in this chain is impaired — nerves, blood vessels, hormones, brain signaling, or psychological factors — erectile function suffers.

Why ED is often a warning sign

The arteries supplying the penis are smaller than the coronary arteries supplying the heart. Atherosclerosis — the buildup of plaque inside artery walls — narrows smaller vessels first. This means ED frequently appears 3 to 5 years before a heart attack or stroke. Studies have repeatedly shown that men with new-onset ED have a meaningfully higher risk of cardiovascular events in the years that follow.

This is why a serious clinician will not just hand you a prescription for sildenafil and send you home. The right response to new ED is to ask: what does this tell us about your overall vascular and metabolic health?

Common causes of ED

Vascular disease

The most common cause of ED in men over 40. Hypertension, high cholesterol, atherosclerosis, smoking, and diabetes all damage the small blood vessels that supply the penis. Improving cardiovascular health often improves erectile function.

Low testosterone

Testosterone supports libido, the brain’s response to sexual cues, and the health of the smooth muscle and nerves involved in erections. Low T can cause low desire, weaker erections, and reduced response to ED medications. Many men with ED also have undetected low testosterone — and treating only one without checking the other often leaves a man frustrated. Read our complete guide to low testosterone for more.

Diabetes and insulin resistance

Diabetes damages both nerves and blood vessels, and is one of the strongest risk factors for ED. Pre-diabetes (elevated fasting glucose or HbA1c without a formal diabetes diagnosis) is also associated with erectile dysfunction.

Sleep apnea

Untreated obstructive sleep apnea suppresses testosterone, raises cortisol, increases cardiovascular risk, and is independently associated with ED. Many men report meaningful improvement in erectile function after treating their sleep apnea — sometimes more than from any pill.

Medications

A surprisingly long list of common medications can cause or worsen ED, including certain blood pressure drugs (especially older beta-blockers and thiazide diuretics), SSRIs and other antidepressants, finasteride, opioids, and some antihistamines. Often, switching medications (with your prescriber’s guidance) resolves the issue.

Mental health and stress

Anxiety, depression, performance pressure, relationship conflict, and chronic stress all affect arousal and erectile function. Psychological causes are more common in younger men but can affect men of any age. ED also worsens depression and anxiety, creating a feedback loop worth interrupting early.

Lifestyle factors

Smoking, excessive alcohol, recreational drug use, sedentary lifestyle, obesity, and poor diet all contribute. The good news: each of these is modifiable, and improvements show up in the bedroom relatively quickly.

How ED should be evaluated

A proper workup goes beyond a quick prescription. Expect a thoughtful clinician to:

Take a detailed sexual history (onset, situational vs. consistent, presence of morning erections, libido)
Review medications, alcohol, recreational drug use, and sleep
Screen for cardiovascular risk factors
Order targeted labs
Discuss psychological and relationship factors openly and without judgment

Useful labs typically include:

Total testosterone, free testosterone, SHBG (morning draw)
LH, FSH, prolactin, estradiol
Fasting glucose and HbA1c
Complete lipid panel
TSH and full thyroid panel
Comprehensive metabolic panel
PSA (baseline before any hormone therapy)
Vitamin D
Home sleep study if any apnea symptoms are present

Treatment options

Lifestyle interventions

Often dismissed as “common sense,” lifestyle changes can produce remarkable improvements: regular aerobic exercise, resistance training, weight loss, smoking cessation, reducing alcohol, treating sleep apnea, and improving sleep quality. These are not optional adjuncts to medication — they treat the underlying vascular and hormonal issues that medications only mask.

PDE5 inhibitors (sildenafil, tadalafil, vardenafil)

The most well-known and well-studied class of ED medications. They enhance the nitric oxide pathway, allowing the natural erection process to work more reliably with sexual stimulation. They do not cause spontaneous erections.

Sildenafil (Viagra): Onset 30–60 minutes, lasts 4–6 hours. Best taken on an empty stomach.
Tadalafil (Cialis): Onset 30–60 minutes, lasts up to 36 hours. Often used as a low-dose daily medication.
Vardenafil (Levitra): Similar to sildenafil with somewhat fewer visual side effects.

These medications are not safe for everyone — particularly men taking nitrates for chest pain, or with certain cardiovascular conditions. Always have them prescribed and monitored by a clinician who has reviewed your medications and history. Buying online from unverified sources is risky and common: studies have repeatedly found counterfeit pills with incorrect doses or other contaminants.

Testosterone replacement therapy

For men with documented low testosterone and symptoms (including ED), TRT can restore libido and improve response to ED medications. TRT is not a stand-alone ED treatment — it works on the desire and brain side of the equation, not the vascular side.

Other medical treatments

When pills are not enough, additional options exist and should be discussed with a qualified clinician:

Vacuum erection devices
Intraurethral or intracavernosal medications
Penile implants (for men who have tried and failed less invasive options)
Pelvic floor physical therapy (often overlooked)
Sex therapy or couples counseling, especially when psychological factors are present

A note on shockwave therapy and stem cells

Low-intensity shockwave therapy and various regenerative treatments are heavily marketed in the men’s health space. The evidence is evolving — some men report benefit, but the studies are mixed, the protocols are not standardized, and the costs are high. Approach these with healthy skepticism, ask for the underlying evidence, and be cautious of clinics that promise dramatic results.

Frequently asked questions

Is ED reversible?

In many cases, yes — particularly when an underlying cause is identified and addressed. Men who lose weight, treat sleep apnea, optimize hormones, switch medications, or change cardiovascular risk factors often see meaningful improvement, sometimes without ongoing medication.

Is it safe to buy ED pills online?

Only from licensed clinicians and pharmacies who require an appropriate medical evaluation. Pills sold without prescription oversight are frequently counterfeit, incorrectly dosed, or contaminated. The bigger problem: they bypass the conversation that might catch the heart disease, diabetes, or hormone issue actually driving the ED.

Can ED happen in your 30s?

Yes. ED in younger men is more often related to anxiety, performance pressure, relationship factors, medications (especially SSRIs), excessive porn consumption patterns, or early metabolic issues. It still warrants a proper evaluation — early-onset ED can be the first warning of cardiovascular risk, and is also very treatable.

Will Viagra work forever?

For most men, yes — there is no evidence that PDE5 inhibitors stop working over time as long as the underlying physiology is intact. If a medication that previously worked stops working, that itself is information: usually it signals a worsening of the underlying vascular, metabolic, or hormonal cause and deserves re-evaluation.

Is ED ever “all in my head”?

Psychological causes are real and common — but in men over 40, there is almost always a physical component too. Even when anxiety is the primary driver, treating the physical contributors usually improves both confidence and performance.

Should my partner be involved?

If you are in a relationship, involving your partner in the conversation usually helps — both practically and emotionally. ED affects relationships, and isolation tends to worsen the cycle. Many couples find that having ED treated openly strengthens rather than weakens their connection.

Where to go from here

If you are struggling with ED, the highest-leverage first step is a comprehensive evaluation — not a prescription. The right plan depends on whether your issue is primarily vascular, hormonal, neurological, psychological, or some combination, and that requires looking at the full picture.

Learn about our sexual health services, our hormone optimization approach, or meet the clinical team.

Take the next step — in private, without judgment.

A confidential consultation is the start of a real plan, not a quick prescription.

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Erectile Dysfunction: Causes, Evaluation, and Evidence-Based Treatments