What Causes Erection Problems? Including Vascular ED

A question I hear a lot is: "Why does it work some days and not others?" The answer is that an erection doesn't depend on the penis alone. It is teamwork between the brain, nerves, blood vessels and hormones. If any one of them stumbles, the result shows up in the penis. This article goes through them layer by layer.

How an erection works

When you are aroused, the brain sends signals through the parasympathetic nerves (the "rest and relax" system) to release nitric oxide. The smooth muscle in the penile blood vessels relaxes, blood flows into the spongy erectile tissue, and the swelling tissue then presses on the veins so that blood can't drain out. That is how the erection is maintained.

On the other hand, when you are stressed or startled, the sympathetic system (the "fight or flight" system) switches on, blood vessels narrow, and the penis can go soft straight away.

1. 1Sexual arousalThe brain signals through the relaxing nerve pathways
2. 2Nitric oxide releasedSmooth muscle in the blood vessels relaxes
3. 3Blood flows inThe spongy tissue fills and expands
4. 4Blood is trappedSwollen tissue compresses the veins; the erection holds

Under stress or fright, the fight-or-flight system tightens blood vessels and an erection can soften at once.

Causes in your thoughts and emotions

1. Little arousal from the start. Some men don't get hard even when they start thinking about sex. This may be due to low desire, chronic fatigue, depression, low hormones, or growing up feeling that sex is wrong. Accepting that sexual thoughts are a normal part of being human, and building closeness with your partner during the day, can help.

2. Stimulation that doesn't quite hit the spot. Everyone likes different kinds of touch. Exploring your own body and talking with your partner about what you enjoy matters more than rushing to penetration.

3. Your mind isn't in the moment. If, during sex, you keep thinking "Will I get hard?" or "Will I finish too fast?", your brain switches into alert mode, which is the opposite of the mode needed for an erection. Read more in Stress, relaxation and erections.

4. Pressure from goals. For example, trying for a baby until sex becomes a scheduled task, or comparing yourself with porn, which is not real life. Read about this in Sex isn't perfect like in the movies.

Your surroundings and your relationship

A crowded house, children running past the bedroom door and no privacy all make it hard to relax. Setting aside private time and space, such as going away together now and then, really does help.

Boredom with the same old routine also has an effect. Couples who can talk openly about trying something new, with both partners' consent, tend to have a livelier sex life. Read more in Common couple problems and how to talk them through.

Physical and lifestyle causes

• Not exercising, carrying belly fat
• Smoking (both cigarettes and e-cigarettes), heavy drinking, recreational drug use
• Too little sleep, or obstructive sleep apnoea
• Some medicines, such as antidepressants: see When antidepressants affect your sex life
• Low testosterone, thyroid problems

Vascular ED

This is the most common physical cause in middle-aged men. There are two types.

1. Not enough blood flowing in (arterial insufficiency)

This is caused by hardening and narrowing of the arteries (atherosclerosis). The inner lining of the blood vessels is damaged by diabetes, high blood pressure, high cholesterol, smoking and age. Symptoms usually develop gradually: erections come more slowly, are not fully firm, and morning erections become less frequent.

2. Blood draining out too quickly (venous leak)

The mechanism that closes off the veins doesn't work well. You can get hard but it doesn't last, softening quickly during sex. It can be caused by degeneration of the erectile tissue, injury, or Peyronie's disease.

Signs that suggest vascular ED

• Gradual, steady worsening over months to years
• Fewer or no morning erections
• Risk factors such as diabetes, high blood pressure, high cholesterol, smoking or being over 40
• It happens in every situation, not only with certain people or in certain places

Diagnosis

The doctor starts with your history, a physical examination and blood tests for sugar, cholesterol and hormones. Some men may have a penile Doppler ultrasound together with an injection that triggers an erection, to look at blood flow in and out. This is usually done by a urologist.

Why vascular ED matters for your heart

The penile arteries are smaller than the heart's arteries, so they show damage first. Studies have found that ED often appears about 2–5 years before symptoms of coronary heart disease. The Princeton IV recommendations (2024) therefore treat ED as an opportunity to find and reduce heart disease risk. Treating ED becomes a doorway to looking after your heart at the same time.

Not enough blood in

Arterial insufficiency

• Arteries hardened and narrowed
• From diabetes, blood pressure, lipids, smoking, age
• Slower, less firm erections
• Fewer morning erections

Blood draining out too fast

Venous leak

• Vein-sealing mechanism works poorly
• Gets hard but does not last
• Softens quickly during sex
• May follow tissue ageing, injury or Peyronie's

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Vascular ED often appears about 2-5 years before symptoms of coronary heart disease.

Care, and when to see a doctor

Treatment starts with lifestyle changes and good control of any chronic illnesses. Where appropriate, a doctor may consider a PDE5 inhibitor, which works well in vascular ED. Read the comparison in Tadalafil vs sildenafil.

See a doctor if erection problems have lasted more than 3 months, if you have a chronic illness, or if you also have chest pain or get breathless easily. At Dr. Kris Clinic we assess the psychological, relationship, hormonal and vascular sides, do basic blood tests, and refer you to a urologist or cardiologist when needed. Consultations are available in English, in person in Surat Thani or online. For the full overview, read Erectile dysfunction (ED).