What Is Erectile Dysfunction (ED)? Causes and Treatments

Erectile dysfunction is the persistent inability to get or keep an erection firm enough for satisfactory sexual intercourse. It affects a substantial share of men at some point in their lives, with prevalence climbing steeply after age 40. Once dismissed as purely psychological or an unavoidable part of aging, ED is now understood as a condition with identifiable physical, hormonal, neurological, and psychological roots, and the range of effective treatments has expanded well beyond a single pill.

How an Erection Actually Works

An erection is fundamentally a vascular event. When a man becomes sexually aroused, nerve signals trigger the release of nitric oxide from nerve and endothelial cells inside the erectile tissue of the penis. Nitric oxide acts as a chemical messenger that relaxes the smooth muscle lining the two spongy chambers (the corpora cavernosa), allowing blood to rush in and fill them under pressure.¹ The expanding tissue compresses the veins that would normally drain blood away, trapping it inside and producing rigidity. Anything that disrupts this chain of events at any step, from the brain’s initial arousal signal to the blood vessels’ ability to dilate, can cause ED.

Vascular Causes Are the Most Common

Because erections depend on healthy blood flow, the same conditions that damage arteries elsewhere in the body damage the small arteries feeding the penis. Atherosclerosis, the buildup of fatty plaques inside artery walls, is a leading driver. High blood pressure, high cholesterol, diabetes, and smoking all accelerate this process. These risk factors create a two-way relationship: vascular disease worsens erectile function, and ED frequently shows up before a man develops obvious heart symptoms.² The connection is so strong that researchers now describe ED itself as a vascular event, closely tied to the health of the endothelium, the thin cell layer lining all blood vessels.³

ED as a Warning Sign for Heart Disease

One of the most clinically useful facts about ED is that it often appears years before a heart attack or stroke. The penile arteries are smaller in diameter than the coronary arteries, so the same plaque buildup that will eventually restrict blood flow to the heart shows up first in the penis. A systematic review found that ED can serve as an early marker to identify men at higher risk of cardiovascular events, because erectile problems usually precede symptomatic heart disease rather than following it.⁴ If you develop ED in your 40s or 50s with no obvious psychological explanation, it is worth talking to your doctor about cardiovascular screening. The erection trouble may be the earliest visible sign of a systemic problem.

Nerve Damage and Neurogenic ED

Erections require intact nerve pathways running from the brain and spinal cord down to the pelvis. Conditions that damage these nerves, such as multiple sclerosis, spinal cord injuries, and diabetes-related neuropathy, can all impair erectile function. But the most well-documented neurogenic cause is surgery in the pelvic region, especially radical prostatectomy for prostate cancer. The cavernous nerves that trigger erections run along the surface of the prostate, and even with modern nerve-sparing surgical techniques, damage is common. Research has found that cavernous nerve injury during prostate and other pelvic surgeries results in ED in more than 80 percent of patients.⁵ This form of ED is a major quality-of-life concern for prostate cancer survivors, and has driven significant research into nerve regeneration strategies.⁶

Hormonal Factors

Testosterone does not single-handedly produce erections, but it plays a supporting role that matters more than many men realize. Low testosterone, or hypogonadism, is one recognized cause of ED.⁷ Animal studies confirm that testosterone deprivation has a damaging effect on the structure of penile tissues and the nerves involved in erection, and that administering testosterone can prevent those changes.⁸ In men with confirmed low levels, testosterone therapy has been shown to improve libido and, in many cases, erectile function. A placebo-controlled trial in men aged 65 and older with low testosterone found that libido improved in proportion to the rise in testosterone levels.⁹

That said, testosterone therapy is not a universal fix for ED. Many men with normal testosterone levels have erectile difficulties driven by vascular or psychological causes, and boosting their testosterone further will not help. The hormone’s role is most relevant when blood tests confirm levels are genuinely low.

Psychological and Emotional Causes

ED is not always a plumbing problem. Anxiety, depression, relationship conflict, performance pressure, and stress can all interfere with arousal. In younger men especially, psychological factors are a common contributor. The mechanism is fairly intuitive: an anxious nervous system ramps up the body’s sympathetic “fight or flight” response, which constricts blood vessels and works directly against the relaxation needed for an erection. Research into anxiety disorders and sexual function suggests that this heightened sympathetic tone distracts from erotic stimuli and impairs the arousal process.¹⁰

The tricky part is that psychological and physical causes frequently overlap. A man who experiences one episode of ED due to a physical issue may develop performance anxiety that perpetuates the problem long after the original cause resolves. This cycle is one reason ED tends to persist once it starts, and why treatment sometimes needs to address both mind and body.

Medications That Can Cause or Worsen ED

A surprisingly long list of common medications can contribute to erectile difficulties. Antidepressants are among the best-known culprits. Sexual dysfunction is a frequent side effect of this drug class, with reported problems ranging from decreased desire and difficulty with arousal to delayed orgasm and erection problems.¹¹ An analysis of the FDA’s adverse event database found that neuropsychiatric medications accounted for about 40 percent of all ED reports, with SSRIs like citalopram, sertraline, and escitalopram, as well as antipsychotics like paliperidone, showing particularly elevated reporting rates.¹² Other drug classes linked to ED include certain blood pressure medications (particularly older beta-blockers and thiazide diuretics), anti-seizure drugs like gabapentin and pregabalin, and opioids.

If you suspect a medication is contributing to ED, do not stop taking it on your own. Your doctor can often switch you to an alternative within the same class that has a lower rate of sexual side effects, or adjust your dose.

How Aging Changes Erectile Tissue

Getting older does not make ED inevitable, but it does shift the odds. Part of the reason is cumulative vascular damage from decades of blood pressure, blood sugar, and cholesterol exposure. But aging also changes the erectile tissue itself. Studies of human penile tissue have found age-related shifts in the ratio of smooth muscle to collagen inside the corpora cavernosa.¹³ Smooth muscle is what relaxes to allow blood in, and collagen is structural scaffolding. As men age, the balance tips toward more collagen and less functional smooth muscle, making the tissue stiffer and less responsive. Research at the molecular level has found that cellular signaling pathways in erectile tissue shift with age in ways that promote fibrosis, essentially scarring, at the expense of healthy tissue turnover.¹⁴ These structural changes help explain why older men may respond less robustly to treatments that work well in younger patients.

How ED Is Diagnosed

Diagnosis typically starts with a medical and sexual history. A doctor will ask about the onset, duration, and circumstances of the problem: whether erections fail entirely or only partially, whether they occur during sleep or masturbation but not with a partner, and whether desire has changed. These details help distinguish between predominantly physical and psychological causes. In one large diagnostic study, medical history alone revealed ED-associated conditions in roughly 57 percent of patients, while blood tests uncovered previously undiagnosed conditions in about 6 percent.¹⁵ Physical examination and injection testing added smaller diagnostic contributions. Blood work typically checks testosterone, blood sugar, cholesterol, and thyroid function. Specialized tests such as penile Doppler ultrasound exist but are reserved for cases where the cause remains unclear or surgery is being considered.

First-Line Treatment With PDE5 Inhibitors

When sildenafil (Viagra) received FDA approval in 1998, it fundamentally changed how ED was treated, transforming a condition that was often managed with injections or implants into one that could be addressed with a pill before sex.¹⁶ Sildenafil and its successors (tadalafil, vardenafil, avanafil) belong to a class called PDE5 inhibitors. They work by blocking the enzyme that breaks down the chemical messenger produced during arousal, essentially amplifying the body’s own erection signal. They do not create desire or spontaneous erections on their own; sexual stimulation is still required.

These drugs are effective for many men, but they fail in roughly 30 to 35 percent of cases. Failure can stem from patient-related factors like incorrect timing, taking the pill with a heavy meal, or unrealistic expectations, as well as medical factors such as severe vascular disease, diabetes, previous pelvic surgery, or low testosterone.¹⁷ Before concluding that the medication does not work, doctors often recommend trying it at least several times with proper instructions, since first-attempt failures are common.

One safety issue worth knowing: PDE5 inhibitors must never be combined with nitrate medications, which are prescribed for chest pain (angina). Both drugs lower blood pressure through overlapping pathways, and using them together can cause a dangerous drop.¹⁸ The required time gap between the two drugs varies depending on which PDE5 inhibitor is used, but the interaction can be severe enough to cause hemodynamically significant blood pressure drops, especially during emergency cardiac situations.¹⁹ Always tell your doctor and any emergency medical team about PDE5 inhibitor use.

When Pills Are Not Enough

For men who do not respond to oral medications, several second-line and third-line options exist. Intracavernosal injection therapy involves injecting a medication directly into the side of the penis before intercourse. The most commonly used drug is alprostadil, which relaxes smooth muscle through a different chemical pathway than PDE5 inhibitors. Clinical evidence shows improved sexual activity in roughly 59 to 78 percent of men using alprostadil preparations.²⁰ The idea of a penile injection understandably makes many men wince, but patients who use it consistently report high satisfaction rates. Injection therapy has also become an important part of penile rehabilitation after prostate surgery, where regular use is thought to help preserve tissue integrity and prevent smooth muscle loss while nerve recovery occurs.²¹

Vacuum erection devices are another non-surgical option. These use a pump to draw blood into the penis mechanically, then a constriction ring at the base holds it in place. They work reliably but feel less natural, and some couples find them cumbersome.

When all else fails, a surgically implanted penile prosthesis is the most definitive treatment. Modern inflatable prostheses consist of two cylinders placed inside the corpora cavernosa, a fluid reservoir, and a small pump hidden in the scrotum. Squeezing the pump transfers fluid into the cylinders, creating an erection on demand. These devices carry high overall satisfaction rates and a low risk of complications.²² Postoperative rehabilitation with vacuum therapy has been shown to improve penile dimensions and satisfaction scores significantly over the first year.²³ Implants are irreversible, since the surgery destroys the natural erectile tissue, but for men who have exhausted other options, they often represent a return to reliable sexual function.

Lifestyle Changes That Make a Real Difference

Because ED is so closely tied to vascular health, the same lifestyle changes that protect your heart also protect your erections. A meta-analysis of dietary patterns and erectile function found that combining a healthier diet with exercise roughly halved the odds of ED and meaningfully improved erection quality scores.²⁴ A Mediterranean-style diet rich in fruits, vegetables, whole grains, nuts, and olive oil has been specifically studied. In men with metabolic syndrome, two years on a Mediterranean diet improved endothelial function, reduced inflammatory markers, and significantly increased the proportion of men who recovered adequate erectile function compared to a control group.²⁵

Quitting smoking, managing blood pressure, controlling blood sugar, losing excess weight, and getting regular aerobic exercise all independently contribute. These changes are not quick fixes, and they work best for men whose ED has a vascular or metabolic component. But they address root causes rather than masking symptoms, which makes them worth pursuing alongside any other treatment.

Cognitive Behavioral Therapy for Psychogenic ED

When anxiety, depression, or relationship issues are central to the problem, psychological treatment can be highly effective, either alone or combined with medication. Cognitive behavioral sex therapy works by identifying and restructuring the anxiety-producing thoughts and beliefs that interfere with arousal. A pilot study of this approach in younger men with non-organic ED found that it improved both erectile function and anxiety scores.²⁶ Couples therapy can also help, particularly when communication around sex has broken down or when a partner’s reaction to the ED has created additional pressure.

Low-Intensity Shockwave Therapy

One of the more talked-about newer treatments is low-intensity extracorporeal shockwave therapy, which delivers acoustic energy pulses to penile tissue. The idea is that these pulses stimulate new blood vessel growth and improve blood flow. It has generated genuine interest because, unlike medications, it aims to restore natural function rather than provide a temporary boost. A randomized sham-controlled trial found that erectile function scores improved significantly at one and two years, though the improvement faded by three years and was no longer statistically different from baseline.²⁷

A Cochrane systematic review offered a cautious assessment: compared to sham treatment, shockwave therapy may produce a small short-term improvement in erectile function, but this effect may not meet the threshold for what patients would consider clinically meaningful.²⁸ A separate meta-analysis of randomized trials was more optimistic about improvements at one, three, and six months, though confidence in longer-term effects was limited by the small number of studies reporting outcomes past six months.²⁹ The evidence is genuinely mixed right now. Shockwave therapy is not yet endorsed as a standard treatment by most major urology guidelines, though it is widely offered at private clinics. If you are considering it, look for a provider using protocols similar to those in published trials and be skeptical of dramatic promises.

The Problem With “Natural” ED Supplements

Walk into any supplement store or browse online marketplaces and you will find shelves of products marketed for male sexual enhancement, typically labeled as “natural” or “herbal.” The reality is that this market has a serious safety problem. Investigations have found that many of these products are adulterated with undeclared pharmaceutical ingredients, often the same active compounds found in prescription ED drugs, but at uncontrolled doses and without any of the medical oversight or quality controls applied to regulated medications.³⁰ A man who believes he is taking a harmless herbal remedy may unknowingly be taking a PDE5 inhibitor, which becomes dangerous if he is also using nitrate medications for a heart condition. The lack of clear regulation in this space makes the products a genuine health hazard. For herbs that are not adulterated, the clinical evidence for effectiveness is generally thin and inconsistent.

How ED Affects Partners and Relationships

ED is often framed as a man’s problem, but it reverberates through the relationship. A large study of female partners of men with ED found that sexual activity dropped significantly after the man developed erectile problems, and that female sexual desire, arousal, orgasm frequency, and satisfaction all declined in parallel. The severity of the decline in women’s sexual satisfaction tracked with the severity of their partner’s ED.³¹ Partners often report feelings of rejection, self-blame, and frustration, particularly when the man avoids discussing the issue or withdraws from physical intimacy altogether. Including a partner in the conversation about ED, and when appropriate in treatment decisions, tends to improve outcomes for both people. ED is a shared problem, and treating it as one tends to produce better results than treating it in isolation.