Erectile dysfunction

Erectile dysfunction is also known as impotence. It means a man is unable to maintain an erect enough penis for satisfactory sexual intercourse. Many men have erection problems at times and the likelihood increases with age.

Key points

  2. It can be distressing and may cause loss of confidence and self-esteem or depression, as well as relationship problems.
  3. There are several solutions, but recognising the problem and talking about it with your doctor are the key first steps.
  4. You can help yourself by cutting down on alcoholstopping smoking and reducing the stress in your life.

How does an erection happen?

Getting an erection is a complicated process. During an erection, the blood vessels that let blood into your penis relax and widen (dilate). This lets more blood in, which causes the sponge-like tissues of your penis to swell and harden.

Your thoughts and senses (touch, hearing, smell and sight) influence a part of your brain that can trigger an erection.

In addition, hormones and other substances determine how your nerves transmit ‘sexual signals’ and how blood vessels respond to the received signals. Arousing thoughts or nervous-system mechanisms such as touch reflexes are 2 ways you can get an erection.

What are the symptoms of erectile dysfunction?

Some estimates indicate that about 40% of men over the age of 40 will have erection problems at times. Symptoms of erection problems include:

  • being unable to get an erection
  • experiencing a partial erection
  • having an erection of a shorter than usual duration.

What causes an erection to fail?


Even when there is an initial physical reason, when this has passed you may still feel anxious about having sex and this can add to the problem.

Alcohol, smoking and recreational drugs

Smoking, drinking alcohol and the use of recreational drugs such as narcotics, stimulants and hallucinogens also affect sexual function.

Chemicals from smoking can interfere with blood flow to your penis and damage the lining of the blood vessels or lead to atherosclerosis (hardening of the arteries). It can also affect the smooth muscle tissue that needs to relax to allow blood to flow in.

Short-term use of alcohol affects sexual desire, reduces performance and delays orgasm and ejaculation.

Medical reasons

Medical  cause  Description
Hormone imbalance Hormone imbalance is a cause of erectile dysfunction in about 7 out of 100 men. Some hormonal conditions that affect erectile function are thyroid disease, acromegaly, low testosterone, cortisol abnormalities and high prolactin. 
Nerve damage Nerve damage can lead to reduced sensitivity or reduced signals to your penis to release the chemicals that cause erection. Nerve damage can be caused by spinal cord injury, multiple sclerosis and Parkinson’s disease. Pelvic trauma from an accident or pelvic surgery, including some cancer operations on your prostate, bladder or bowel, may result in nerve damage leading to erectile dysfunction. Stroke can also lead to erectile dysfunction.
Blood vessel disease Blood vessels often become narrowed and hardened with increasing age. This reduces blood supply to your penis. Diseases that affect blood vessels include diabetes, hypertension and high cholesterol.
Other conditions Obesity (due to multiple reasons such as low testosterone and inflammation), obstructive sleep apnoea, prolonged cycling (damage to pudendal nerve), low physical activity and chronic kidney disease can all affect erectile function.


Some medicines, including over-the-counter medicines, can cause sexual problems, including getting and maintaining an erection. Medication is a common cause of erectile dysfunction for 25 out of 100 men using medication. This varies depending on the person and type of medication.

Medicines known to cause sexual problems in some people
  • Some antidepressants, particularly SSRIs
  • Antipsychotics
  • Some medicines for heart problems, particularly thiazide diuretics and spironolactone – beta blockers only have a small increased risk of erectile dysfunction (5 per 1000)
  • Some anti-epileptic medicines
  • Opioids such as morphine, oxycodone (thought to be due to reducing testosterone levels)
  • Anti-androgens
  • Some treatments for cancer
  • Some medicines for bladder and prostate problems
  • Corticosteroids such as prednisone, dexamethasone


Psychological reasons

There are a range of psychological factors affecting erection including:

  • existing values or attitudes towards sex
  • stress, guilt, depression or fatigue
  • performance-related anxiety about your performance during sex
  • traumatic past experiences including sexual abuse 
  • poor body image
  • problems with intimacy and communication
  • intercourse less than once per week (twice the risk of developing erectile dysfunction).

Pornography consumption is not generally a cause.


What are the links between low libido, premature ejaculation and erectile dysfunction?

Other sexual problems   Description
Low libido Erectile dysfunction may lead to low libido. However, most people with erectile dysfunction do not complain of low libido. Libido tends to reduce with age. Many of the causes are the same as for erectile dysfunction.
Premature ejaculation Some men with premature ejaculation also have erectile dysfunction, but most do not. Other than psychological factors, partner factors, especially vaginismus (excessive female pelvic floor contraction), can be a cause. Some men with erectile dysfunction may “rush” sexual intercourse in order to avoid losing their erection. The main treatments are the start-stop technique, the squeeze technique and having more sexual intercourse. SSRIs can be used as a treatment in order to delay ejaculation. Topical anaesthetics and counselling can also be used.
Other types of sexual problems in men Delayed ejaculation and retrograde ejaculation are other conditions that men can experience.

How is erectile dysfunction diagnosed?

Many men are unhappy with their ability to get or maintain an erection, but only 5% of these men seek help. This is because most men, in general, are unwilling to discuss their sex life, even when it is going well.


They can check your health and any current medications for likely side effects. If psychological reasons are suspected, your doctor can advise you on what would help, including helping you access counselling services you (and your partner) may benefit from.

Tests by your doctor may include:

  • a physical examination, which may include your genitals and prostate gland
  • checking your medications for side effects
  • blood and urine tests for hormones, blood lipids, thyroid, liver and kidney function and diabetes.

If your erection problems have a medical cause, your doctor can explain the treatment options, the techniques needed to make them work and their suitability for your needs based on your overall health.

How is erectile dysfunction treated?

There are several treatments for erectile dysfunction. Your doctor can advise you on the benefits and drawbacks of each.

Lifestyle changes


Psychological counselling 

This can be useful even if there is a medical cause, as it gives you a chance to talk about how you feel about having erectile dysfunction. If there is an underlying psychological reason for the difficulty, this is a safe place to explore what this might be and what you can do about it. This is generally not available as a funded service and you would normally need to pay for this privately. If you have been sexually abused, then you may be able to access free counselling through ACC.

Sensate focus exercises


Tablets (taken by mouth)



If the tablets mentioned above don't work, then injecting a medicine called Caverject into the base of your penis is another option. It allows most men to get an erection, which may last beyond ejaculation. Some men may be put off by this method, but the injector devices are simple and convenient to use and the procedure is virtually painless. Your doctor or sexual health specialist needs to show you in person how to use it safely.

Other possible treatments


Do herbal products work?



Self-care for erectile dysfunction




  1. Sexual dysfunction in men – when Viagra doesn't work Goodfellow Unit, NZ, 2019
  2. Erectile dysfunction BPAC, NZ, 2008
  3. Erectile Problems Best Health, UK, 2014
  4. Dietary supplements for erectile dysfunction – a natural treatment for ED?  Mayo Clinic, US, 2017 
Credits: Health Navigator Editorial Team. Reviewed By: Dr Jeremy Steinberg, FRNZCGP Last reviewed: 13 May 2020