What Is Erectile Dysfunction? A Complete Guide to Causes, Symptoms and Treatment

Medically reviewed by Professor Ilan Gruenwald, MD, FECSM — Consultant Urologist, Neuro-Urology and Sexual Medicine

Erectile dysfunction (ED) is the medical term for a persistent difficulty getting or keeping an erection firm enough for satisfactory sexual activity. It’s one of the most common conditions in men’s health prevalence rises with age, and by some estimates over 350 million men worldwide live with some degree of it. It is not simply “a normal part of getting older,” and in a meaningful number of cases it’s an early warning sign of cardiovascular or metabolic disease, which is exactly why getting it properly assessed matters not just for your sex life, but for your general health.

For years ED was assumed to be mostly psychological. Current medical understanding is the opposite: in the majority of cases, the root cause is physical — usually something affecting blood flow, the structure of penile tissue, or nerve signalling — even when stress or anxiety makes the experience of it worse.

Facts about ED that are worth knowing

ED can appear at any age, but prevalence rises steadily with age. Broadly speaking, epidemiological studies put the rate at roughly 10-25% in men under 40, around 40% at age 40, about 50% from age 50 onward, and 70-95% from age 70 onward.
Around 8 in 10 cases of chronic ED have a physical (organic) cause rather than a purely psychological one.
Men with diabetes or obesity are disproportionately affected – some studies report ED in up to 75% of men with diabetes and 79% of men with obesity.
Cardiovascular disease is the single most common physical risk factor for ED in men over 40 – and research shows this link exists in younger, apparently fit men too, not just older or unwell ones.
A long list of common medications can cause ED as a side effect, including some blood pressure medications, diuretics, antidepressants, antipsychotics, medications for an enlarged prostate, antihistamines, and sedatives.
ED is associated with a significantly increased risk of depression.
Despite how common it is, most men who experience ED don’t seek professional advice about it.

How does an erection actually happen?

Understanding the mechanics helps explain why so many different things – vascular, neurological, hormonal, or structural – can each disrupt the same end result.

The penis contains two cylindrical chambers called the corpora cavernosa – spongy tissue riddled with tiny blood vessels. An erection unfolds in stages:

A signal reaches the brain. Sexual stimulation – physical touch, thought, sight, even smell – travels as a nerve signal down the spinal cord to the penis.
Nerve chemistry triggers relaxation. The nerve signal causes local nerve cells to release nitric oxide (NO). Inside the smooth muscle of the penile blood vessels, this triggers production of a molecule called cGMP, which relaxes the surrounding muscle.
Blood flows in. As the smooth muscle relaxes, blood vessels widen and blood floods into the corpora cavernosa, making the penis longer and thicker.
The blood gets “locked in.” As the chambers fill, the tunica albuginea – a collagen-rich sheath wrapped around them – stretches and presses against the veins that would normally drain blood away. erection firm the tunica’s strength and elasticity depend on a healthy network of collagen fibres. When blood flows in and veins are compressed- this causes a significant rise in intracorporal pressure (ICP). Blood retention & a high ICP result in a firm erection for the full duration of sexual activity.
The erection subsides. After ejaculation, or when stimulation stops, an enzyme called PDE5 breaks down cGMP. The vessels return to their resting state, the venous lock releases, and the penis gradually softens.

How do I know if it’s erectile dysfunction?

ED is only one part of a broader category called male sexual dysfunction, which also includes changes in libido, problems with ejaculation, and difficulty reaching orgasm – so it’s worth being clear about which one you’re actually dealing with.

The defining symptom of ED is difficulty achieving or maintaining an erection firm enough for the sexual activity you want to have. But there’s an important distinction: an occasional off night – after drinking, when you’re exhausted, distracted, or stressed about something unrelated – isn’t ED. A persistent pattern over weeks or months is what defines the condition clinically.

If you suspect you have ED, the right next step is talking to a doctor. A proper diagnosis matters for two reasons: getting the most appropriate treatment, and ruling out (or catching early) an underlying condition like cardiovascular disease, diabetes or high blood pressure – conditions that often show up as ED before they’re diagnosed on their own.

What causes erectile dysfunction?

Causes are generally grouped into physical (organic), psychological (psychogenic), or a combination of both.

Physical causes

Roughly 8 in 10 cases of chronic ED have a physical basis, most commonly involving reduced blood flow to the penis.

Cardiovascular disease. The leading physical cause of ED in men over 40, responsible for roughly half of all cases. Hardening and narrowing of the arteries supplying the penis (atherosclerosis) restricts blood flow, often producing partial erections or a longer time to reach full erection. Risk factors – obesity, high blood pressure, high cholesterol, smoking, inactivity – frequently cause ED before they show up as diagnosed heart disease, which is why ED is sometimes described as an early warning sign.

Venous leak. As men age, the collagen fibres in the tunica albuginea naturally weaken and their number decreases. This natural phenomena of collagen degeneration results in a state that the tunica can no longer compress the veins effectively, blood drains out of the penis faster than it should, and the erection softens prematurely – even if blood flow in is perfectly normal. Despite the name, this isn’t primarily a vein problem; it’s a tissue-elasticity problem. Difficulty maintaining an erection, rather than achieving one, is often an early sign of this specific cause.

Neurological conditions. Anything that disrupts the nerve pathway from the brain to the penis can cause ED – Parkinson’s disease, multiple sclerosis, stroke, spinal cord injury (including from a slipped disc or surgery), and pelvic surgery or radiotherapy.

Diabetes. Affects both the blood vessels and the nerves supplying the penis. High blood sugar over time stiffens the arteries (reducing their ability to widen for an erection) and damages the nerves (diabetic neuropathy), often producing a combined vascular-and-neurological picture.

Hormonal factors.

Low testosterone – testosterone plays a role in libido, erectile tissue structure and function; levels decline gradually from around age 35, typically 1–2% per year, and low levels are linked to fewer, weaker erections and reduced desire.
Thyroid dysfunction – both an underactive and overactive thyroid can disrupt hormone balance, sexual desire, and testosterone levels.
Cushing’s syndrome – elevated cortisol is linked to hormonal imbalance, arterial narrowing and reduced testosterone.
Elevated prolactin – high levels suppress testosterone production and can contribute to ED.

Anatomical issues, including Peyronie’s disease (scar tissue causing curvature), significant trauma to the penis, and, rarely, an unusually small penis.

Medication side effects, including some blood pressure medications, diuretics, antidepressants, antipsychotics, prostate medications, and antihistamines.

Long-distance cycling, due to sustained pressure on the pudendal nerve and blood vessels from the saddle.

Post-viral effects. Emerging research has associated COVID-19 infection with a heightened short-term risk of ED in some men, possibly via effects on penile blood vessels or testosterone production. Most cases resolve, though some men report longer-lasting symptoms. This remains an active area of research.

Psychological causes

Purely psychological factors account for roughly 1 in 10 cases of chronic ED and include performance anxiety, general stress, relationship difficulties, guilt, and psychiatric conditions such as clinical depression or generalised anxiety disorder.

A useful clue: if you still get firm erections during sleep, on waking, or during masturbation, but struggle in partnered sexual situations, a psychological component is more likely. Psychogenic ED also tends to appear suddenly, whereas physical ED usually develops gradually.

It’s also worth knowing that psychological and physical causes often feed each other – a physical episode of ED can trigger performance anxiety, which then makes the problem worse and harder to untangle.

“Impotence” vs. erectile dysfunction – is there a difference?

You’ll see both terms used, sometimes interchangeably, and it’s worth knowing why.

Impotence is the older term, from the Latin impotentia (“lack of power”). Historically it was a catch-all for a wide range of male sexual difficulties, and for centuries was attributed – inaccurately – to psychological weakness or even superstition. Merriam-Webster still defines it two ways: generally, as “lacking in power, strength, or vigour,” and medically, as “an abnormal physical or psychological state of a male characterised by inability to engage in sexual intercourse because of failure to have or maintain an erection: erectile dysfunction.”

Erectile dysfunction is the modern, medically precise term. It refers specifically to one stage of male sexual function – the erection itself – distinct from the three other stages: desire, orgasm, and ejaculation. Clinicians have largely moved away from “impotence” in professional use, partly because of its imprecision and partly because of the negative, shame-laden connotation it carries.

Worth flagging while we’re at it: ED is not the same as infertility. ED is a difficulty achieving or sustaining an erection sufficient for penetrative sex. Infertility relates to sperm production or ejaculation. A man can have one without the other.

What are the symptoms of ED?

ED typically develops gradually, with intermittent difficulty that becomes more consistent over time.

Difficulty achieving a firm erection. A persistent inability to get an erection firm enough for satisfying sexual activity. Contrary to a common assumption, ED doesn’t mean never getting an erection – inconsistent ability counts too.

Difficulty maintaining an erection. Achieving an erection but losing it before, or during, sex – whether it fades quickly or comes and goes.

Losing the erection before climax. Often linked to a psychological component such as performance anxiety or general stress.

Partial erections. ED exists on a spectrum, from mild to complete absence of erection. Clinicians often use the Erection Hardness Score (EHS), a simple 0–4 scale:

Score	Description
0	The penis does not enlarge
1	The penis enlarges but isn’t hard at all
2	The penis is hard, but not hard enough for penetration
3	Hard enough for penetration, but not fully hard
4	Fully hard

How is ED diagnosed?

Start with your GP. They’ll ask about your general health, medical history, current medications, and lifestyle, and carry out a physical examination – checking for signs of circulation problems, examining the genital area, and, where relevant, a rectal exam to check the prostate.

Targeted follow-up, based on what’s suspected:

Suspected hormonal cause → blood tests for testosterone and related hormones, and possible referral to an endocrinologist.
Suspected vascular cause → a Doppler ultrasound to assess blood flow to the penis.
Suspected neurological cause → referral for more detailed neurological assessment.
Suspected cardiovascular risk → blood pressure, cholesterol and blood sugar checks, since ED often precedes a formal cardiovascular diagnosis.

If no physical cause is found, or alongside treatment for a physical cause, referral to a psychosexual therapist or counsellor is common – in the UK, this typically means a therapist accredited by COSRT (the College of Sexual and Relationship Therapists) or a clinician working within NHS or private sexual health services.

What are the treatment options for ED?

Treatment depends on the underlying cause, severity, and personal preference. Here’s the full landscape, in the order most UK clinicians would typically consider them.

First-line: oral medication (PDE5 inhibitors)

Medicines such as sildenafil (Viagra and similar) , tadalafil (Cialis and similar) and vardenafil (Levitra and similar) work by blocking the PDE5 enzyme, extending the window during which increased blood flow can produce and sustain an erection. Taken 30–60 minutes before sexual activity (tadalafil lasts longer and offers more flexibility in timing). Effective for many men, particularly those with mild-to-moderate vascular impairment. Possible side effects include headache, flushing, nasal congestion and indigestion; these medicines can interact with nitrates and some heart medications, so they’re not suitable for everyone.

Vacuum erection devices

A cylinder placed over the penis draws blood in by creating a vacuum; an elastic ring is then fitted at the base to maintain the erection for roughly 30 minutes. Non-drug and low-risk, though it requires some manual coordination and planning immediately before sex.

Penile injections

A self-administered injection into the side of the penis relaxes smooth muscle and dilates blood vessels, producing an erection typically within minutes. Highly effective for many men, including some who don’t respond to oral medication, but requires proper training and comfort with self-injection.

Urethral suppositories (MUSE)

A small pellet inserted into the urethra, delivering medication that widens blood vessels within 10–15 minutes. Generally considered less effective than injections but avoids needles.

Shockwave therapy (Li-ESWT)

Low-intensity acoustic (sound) waves delivered to the penile tissue over a course of clinic sessions, aiming to stimulate new blood vessel growth and improve circulation. Evidence is mixed – some studies show modest benefit, particularly for men with mild vascular ED – and major urology guidelines don’t yet list it as an established standard of care. It remains under active research, and is mostly considered experimental.

Radiofrequency therapy (RF therapy): Vertica® – home use

Vertica is a CE-marked, MHRA-cleared, drug-free medical device for home use, delivering low-intensity RF energy to the penile tissue. Rather than producing an on-demand erection, it’s designed to support collagen renewal in the tunica albuginea, increase blood inflow, support cellular health and enhance nerve function – targeting the structural side of erectile function rather than providing short-term symptomatic relief. As mentioned before- today the understanding is that ED relies on blood inflow, cellular function, tissue-elasticity problem and tunal structure. It’s used as a regular at-home routine, separate from the timing of sexual activity, which some men find preferable to planning around a pill or injection.

In a clinical study published in the International Journal of Impotence Research, the majority of men using Vertica showed measurable improvement in erectile function within the first month, with continued improvement by three months – supported by objective changes in blood flow, not just self-reported outcomes.¹

Vertica is intended for men with mild-to-moderate ED, including those with venous leakage or diabetes-related ED, and doesn’t require a prescription. It isn’t a substitute for urgent medical assessment, and outcomes vary depending on the underlying cause and consistency of use.

Surgical options

Penile implants – for men who haven’t responded to other treatments. Two main types: semi-rigid rods (constant firmness, bent down when not in use) and inflatable implants (pumped up via a scrotal pump for a more natural resting, flaccid state). High success and satisfaction rates, reserved for more severe or treatment-resistant cases.
Penile revascularisation (bypass) surgery – a narrower option, suitable only for ED caused by a specific, identifiable arterial blockage, usually after a physical trauma or in young otherwise healthy patients and only when there are no other identifiable significant risk factors.

Psychosexual therapy and counselling

Where ED has a psychological component – performance anxiety, stress, depression, or relationship difficulties – therapy (individual or with a partner) with a psychosexual counsellor or sexologist can be highly effective, either alone or alongside a physical treatment.

Where ED research is heading

Current research continues to focus on treatments that address the underlying cause rather than providing only in-the-moment symptomatic relief. Two areas worth knowing about, with an honest note on how far along the evidence actually is:

Platelet-rich plasma (PRP) injections. PRP uses a concentrated preparation of the patient’s own blood platelets and growth factors, injected into penile tissue to encourage repair. A 2024 meta-analysis of placebo-controlled trials found PRP outperformed placebo on several validated outcome measures, with the benefit appearing to grow over the following months.² A separate 2024 literature review of PRP for ED and Peyronie’s disease found small-to-moderate improvements with mild, temporary side effects.³ Bottom line: PRP is not currently FDA-approved or endorsed by major European or American urological associations as a proven ED treatment. The studies to date are small, and larger, methodologically consistent trials are needed before firm conclusions can be drawn.

Stem cell therapy. Research explores whether stem cells can regenerate the vascular, nerve and muscle tissue involved in erections – of particular interest for ED following nerve damage from prostate surgery (where ED can affect up to 90% of patients) and diabetes-related ED. Early clinical studies have reported meaningful improvement after stem cell injection in both groups.⁴ Bottom line: most evidence to date comes from animal studies; human clinical trials remain limited. Larger phase 2/3 human trials are expected to provide a clearer scientific basis in the coming years.

To date these 2 latter treatments are considered experimental as well.

Can erectile dysfunction be reversed?

In many men, ED can improve significantly – particularly when an underlying condition (diabetes, high blood pressure, low testosterone) is identified and addressed early, and when treatment targets the structural or vascular cause rather than only the symptom. Outcomes vary depending on the cause, overall health, and how established any tissue changes already are. Treatments that focus on restoring blood flow and tissue health may support longer-term improvement, while purely symptomatic treatments act only for a limited period.

When should I see a doctor?

See a doctor if erectile difficulties persist for more than a few weeks, appear suddenly, or come with other symptoms such as pain or changes to the penis. Because ED is so often linked to cardiovascular and metabolic health, it’s worth taking seriously even if it feels like a minor inconvenience – it can be an early signal of a broader health issue, sometimes appearing well before that issue is otherwise diagnosed.

Gruenwald I, Appel B, Shechter A, Greenstein A. Radiofrequency energy in the treatment of erectile dysfunction – a novel cohort pilot study on safety, applicability, and short-term efficacy. International Journal of Impotence Research. 2023;36:728–733. DOI: 10.1038/s41443-023-00733-1 ↩

Meta-analysis of placebo-controlled PRP trials for ED, published 2024 (tandfonline.com/doi/pdf/10.1080/13685538.2024.2358944). ↩

Literature review of PRP for ED and Peyronie’s disease, published 2024 (link.springer.com/article/10.1007/s00345-024-05065-3). ↩

Reviews of stem cell therapy for ED following nerve damage and diabetes-related ED, published 2024 (link.springer.com/article/10.1007/s40259-024-00650-9; ncbi.nlm.nih.gov/pmc/articles/PMC10330142/). ↩

This information is provided for general educational purposes only and is not a substitute for professional medical advice. If you’re experiencing erectile difficulties, please speak to your GP or another qualified healthcare professional.

Always read the Instructions for Use (IFU) before use. Vertica® is a registered trademark of Ohh-Med Medical Ltd.

Professor Ilan Gruenwald, MD, FECSM Consultant Urologist specialising in neuro-urology and male and female sexual dysfunction. Graduate of the Tel Aviv University Faculty of Medicine, specialist qualification in urological surgery and neuro-urology and sexual dysfunction, with further training in pelvic floor disorders and urinary incontinence at St George’s Hospital, London. Research focus: male and female sexual dysfunction, pelvic floor neurophysiology and pathology and urinary incontinence.

Posted on: August 30, 2026