Understanding the Causes of Erectile Dysfunction (ED)

Erectile dysfunction (ED) usually has more than one cause. Physical health, mental health, lifestyle and medicines can all play a part, and they often overlap. Understanding what might be behind your ED helps your doctor find the right approach, and it can also uncover health problems that are worth treating in their own right.

This article looks at the causes of ED in depth. For a general overview, including how common ED is and what treatment involves, see Erectile dysfunction in Australia: causes and when to get help.

How an erection works

When you’re sexually aroused, your brain sends signals along the nerves to the penis. Blood vessels in the penis relax and widen, letting blood flow into spongy tissue, which makes the penis firm. Veins are squeezed so the blood stays in place. Hormones, particularly testosterone, support sex drive and this whole process.

So anything that affects your blood vessels, nerves, hormones or state of mind can affect erections.

Blood vessel and heart conditions

Problems with blood flow are among the most common physical causes of ED, especially in men over 40. Conditions that damage or narrow blood vessels include:

• heart and blood vessel disease
• high blood pressure
• high cholesterol
• smoking-related damage to the arteries

Because the arteries in the penis are small, ED can appear before other signs of heart disease. Healthdirect notes that ED can be the first sign of conditions such as cardiovascular disease, diabetes, high blood pressure and high cholesterol. This is one of the main reasons to see a GP rather than ignore it. Our pages on blood pressure and cholesterol explain how these are checked and managed.

Diabetes

Over time, high blood sugar can damage both blood vessels and nerves, so diabetes is a common cause of ED. ED can sometimes be the symptom that leads to a diabetes diagnosis. Keeping blood sugar, blood pressure and cholesterol well controlled can help protect erections as well as your general health.

Hormone problems

Low testosterone can reduce sex drive and contribute to erection problems, although it’s less often the main cause than people think. Other hormone issues, such as thyroid problems or high levels of the hormone prolactin, can also play a part. A GP may suggest blood tests if your symptoms point that way, for example low libido, tiredness or loss of muscle. Our thyroid page has more on thyroid testing.

Nerve conditions and surgery

Erections depend on healthy nerve signals. Things that can interfere with these include:

• conditions such as multiple sclerosis, Parkinson’s disease or stroke
• spinal cord injury
• surgery or radiotherapy for prostate, bladder or bowel cancer
• injury to the pelvis or penis

Men who have had prostate cancer treatment often benefit from specialist support, and a GP can help arrange this.

Psychological and emotional causes

Your mind plays a big part in arousal. Psychological causes are more common in younger men, but they can affect anyone, and they often add to a physical cause. They include:

• Performance anxiety. One difficult experience can lead to worry about the next time, and that worry makes it harder to get an erection. This cycle is very common.
• Stress from work, money or family.
• Depression and anxiety, which can reduce interest in sex and affect erections. Some treatments for these conditions can also affect sexual function.
• Relationship difficulties, such as conflict, poor communication or loss of closeness.
• Past negative sexual experiences or feelings of guilt or shame about sex.

A clue that the cause may be mainly psychological is still having erections at some times (for example, on waking or when alone) but not with a partner. Even so, it’s worth having a check-up. Our pages on anxiety and depression explain how a GP can help.

Medicines that can contribute

A number of medicines can affect erections or sex drive as a side effect. These can include some medicines for:

• high blood pressure
• depression and anxiety
• psychosis
• prostate enlargement or prostate cancer
• allergies, and some strong pain relief

If you think a medicine may be affecting you, don’t stop it on your own. Talk to your doctor, who may be able to adjust the dose or suggest an alternative.

Lifestyle factors

• Smoking damages the lining of blood vessels and reduces blood flow.
• Alcohol: drinking a lot can stop an erection on the night, and heavy drinking over time can damage nerves and lower hormone levels.
• Recreational drugs can affect erections and sex drive.
• Being inactive and carrying extra weight raise the risk of diabetes and heart disease, which in turn affect erections.
• Poor sleep, including sleep apnoea, can affect energy, mood and hormone levels.

The upside is that these are things you can change. Regular activity, stopping smoking and cutting back on alcohol help your heart and blood vessels as well as your sex life.

Who is more at risk?

ED becomes more common with age, mainly because the conditions that cause it become more common. You’re more likely to have ED if you:

• have diabetes, heart disease, high blood pressure or high cholesterol
• smoke or drink heavily
• are above a healthy weight or not very active
• live with depression, anxiety or ongoing stress
• have had prostate, bladder or bowel surgery or radiotherapy

How a doctor works out the cause

A GP will usually ask about when the problem started, whether it happens every time, whether you still get morning erections, your sex drive, your mood, your relationship, alcohol and smoking, and any medicines you take. They may arrange blood tests to check blood sugar, cholesterol and sometimes hormone levels, and suggest a blood pressure check. Some men will need a referral to a urologist or other specialist.

When to get urgent help

Call 000 or go to your nearest emergency department if you have:

• chest pain, pressure or shortness of breath, including during or after sex
• an erection that lasts more than 3 to 4 hours, or is painful and won’t go down
• sudden severe pain, swelling or bruising of the penis after an injury
• new numbness or weakness in the legs, or loss of bladder or bowel control

How Teldoc can help

Our AHPRA-registered GPs can assess ED by phone or video, 7 days a week from 9 am to 7 pm (Sydney time), and most patients are seen within 15 minutes. Your doctor can talk through possible causes, arrange blood test referrals, prescribe treatment if clinically appropriate with an eScript sent to your phone, and refer you to a specialist if needed.

ED consultations are a private fee: $55 on weekdays and $75 on weekends and public holidays, with no Medicare rebate. See our fees page or learn more about erectile dysfunction treatment online. If talking about ED feels hard, our guide to overcoming ED stigma may help.

Frequently asked questions

What is the most common cause of erectile dysfunction?

In older men, problems with blood flow linked to heart disease, high blood pressure, high cholesterol, diabetes or smoking are common causes. In younger men, stress and anxiety play a bigger part. Often there’s more than one cause.

Can stress cause erectile dysfunction?

Yes. Stress, anxiety and worry about performance can make it hard to get or keep an erection, and one bad experience can lead to a cycle of worry. A GP can help with strategies, counselling and other treatment.

Can medicines cause ED?

Yes. Some medicines for blood pressure, depression, anxiety, psychosis and prostate conditions can affect erections. Don’t stop a medicine yourself. Talk to your doctor about other options.

Is ED caused by low testosterone?

Sometimes, but low testosterone is less often the main cause than many people think. If you also have low sex drive or tiredness, your GP may suggest a blood test.

Can lifestyle changes improve ED?

For some men, yes. Stopping smoking, drinking less alcohol, being more active and reaching a healthier weight can improve blood flow and general health, which may help erections.

This article is general health information and isn’t a substitute for advice from your own doctor. If you’re worried about your health, speak to a GP. In an emergency, call 000.

Medically reviewed by Dr Vafa Derakshan (MBBS, FRACGP), September 2026