Erectile dysfunction (ED) or impotence is the inability to achieve or maintain an erection strong enough for sexual intercourse.

How common is ED?

It becomes more common with age, affecting up to 67% of men by age 70. A Perth study looked at 1240 men (age > 18 years) and asked them to fill out a questionnaire. About 40% of the men reported having ED, with 18.6% reporting complete ED. Only 11.6% of men with ED received treatment. ED is a medical condition that can be treated. It should not be viewed as an unavoidable part of the ageing process.

What are the causes of ED?

ED is multifactorial; there are many causes for it:

  • Social (e.g., age, occupation, relationships).
  • Lifestyle (e.g., smoking, substance abuse, obesity, alcohol).
  • Psychological health (e.g., stress, anxiety, depression).
  • Medications (e.g., antihypertensives, antidepressants, hormones, cholesterol-lowering drugs).
  • Neurological diseases (e.g., stroke, spinal cord disease, multiple sclerosis).
  • Surgery (e.g., major pelvic surgery, radical prostatectomy, resection of rectum). Nerve-sparing during prostate cancer surgery can reduce the risk of ED.
  • Radiotherapy (external beam or radioactive seed irradiation of the pelvis).
  • Penile disorders (e.g., Peyronie’s disease, penile trauma).
  • Cardiovascular disease (e.g., hypertension, heart attack, peripheral vascular disease, high cholesterol level).
  • Endocrine disorders (e.g., diabetes, low testosterone levels, thyroid disease).
  • Any acute or chronic illness (e.g., kidney failure, major surgery).

The most common cause is vascular (blood vessel) disease. The incidence of ED is higher in men with hypertension (26%), ischaemic heart disease (38%), peripheral vascular disease (57%) and diabetes (34%). That is why the presence of ED in an otherwise healthy man may indicate some underlying vascular disease.

What is involved in the assessment of ED?

History taking

A thorough history should be obtained including medical and sexual history. Medical risk factors for ED should be checked – in particular, heart disease, diabetes, and vascular disease. The medications being taken, smoking history, and psychological factors should all be ascertained. In terms of the ED, medical causes can often be differentiated from psychological causes by some of the symptoms.

Medical causes (organic)

Psychological causes

Gradual onset

Fast onset

Older man

Younger man

Morning erections poor

Morning erections normal

Consistent, persistent ED

Intermittent, variable erection

Has risk factors

No risk factors

Masturbatory erection poor

Masturbatory erection good

A useful questionnaire called the IIEF-5 (International Index of Erectile Function) contains five questions that can help the doctor identify and assess the severity of the problem.

Download International Index of Erectile Function (IIEF - 5) – PDF (35 KB)

Physical examination

The physical examination should cover the external genitalia (penis and testes), prostate, peripheral pulses, and secondary sexual characteristics.


Some blood tests may be indicated:

  • Fasting blood glucose (diabetes).
  • Kidney function.
  • Cholesterol levels (vascular disease).
  • Liver function (drug/alcohol abuse).
  • Testosterone level (libido) +/- other hormone tests (prolactin, LH, FSH).
  • PSA levels.
  • Thyroid hormones levels.

Other tests are more uncommonly done:

  • Sleep studies looking at the frequency and degree of spontaneous erection.
  • Doppler ultrasound looking at penile tissue and vasculature.
  • Cavernosography and cavernosometry are relatively invasive tests which look for the leakage of penile blood internally through a vein, such that an erection cannot be maintained.

How do I know if I am fit enough to resume sex?

One’s overall fitness should also be assessed before resuming sexual intercourse. High-risk patients are those with heart risk factors like uncontrolled hypertension, unstable angina, recent heart attack or stroke (< 6 weeks), severe heart valve disease and irregular heart rhythm.

In general, a man is fit enough for sex if he can do the following without chest discomfort or undue breathlessness:

  • Walk 1 km on the flat in 15 minutes (equivalent exertion to intercourse).
  • Climb 2 flights of stairs (20 steps) in 10 secs (equivalent exertion to orgasm).

What are the treatments?

Treatments should always start with non-invasive to more invasive ones. They range from lifestyle modifications, treating reversible medical conditions, oral drug therapy, penile insertion therapy, penile injection therapy, vacuum device and penile prosthesis surgery.

Lifestyle modification

  • Stop smoking and substance abuse.
  • Lose weight, exercise.
  • Stress relief.
  • Changing medications which may cause ED.
  • Counselling if there are psychological or relationship issues.

Treat reversible medical problems:

  • Control diabetes and hypertension.
  • Treat hormonal imbalance (thyroid hormones, testosterone).

Oral medications (PDE5 inhibitors)

The mainstay of oral drug treatment is a class of medications called PDE5 inhibitor. Some examples of these drugs are Viagra, Cialis and Levitra. They work by enhancing the natural response to sexual stimulation, not by directly inducing an erection as with injectable therapies. They cause the blood vessels in the penis to relax and engorge with blood and thus an erection will ensue. They are effective in about 8 out of 10 men with ED.

Side effects

  • Headache, facial flushing, and nasal congestion.
    • This is due to the effect of dilating blood vessels elsewhere other than the penis.
    • A nasal decongestant spray or paracetamol can help relieve symptoms.
  • Reflux and indigestion
    • Due to the relaxation of the oesophageal sphincter.
    • Avoid a heavy meal before taking the drug and take an antacid for symptom relief.
  • Visual side effects:
    • In a few patients, Viagra and Levitra can cause temporary blue-green vision, light sensitivity, or blurred vision.
    • These drugs do not cause blindness.
  • Back pain and muscle aches:
    • Cialis may cause lower back pain and muscle aches in the thighs and buttocks.
    • They usually spontaneously resolve within 48 hours.
  • Priapism (prolonged erection):
    • More common if a PDE5 inhibitor is used in combination with other ED therapy.

Some men should not have PDE5 inhibitors

  • Recent heart attack (< 3 months ago) or stroke (< 6 months ago).
  • Men on nitrate medications. Nitrate drugs are mainly used to treat angina. The combination of PDE5 inhibitor and nitrates can lead to life-threatening low blood pressure.
  • Men who are not fit enough to resume sex.
  • Uncontrolled low blood pressure (<90/50) or high blood pressure (> 170/110).
  • Men with high-risk factors for heart disease.
  • Men on blood pressure pills including certain prostate medications (alpha-blockers) should consult their doctor before taking PDE5 inhibitors.

When taking PDE5 inhibitors follow these instructions to increase efficacy

  • Limit alcohol intake.
  • A full stomach delays the onset of action when Viagra and Levitra are taken within 2 hours of eating.
  • Attempt at least 4 – 8 times before concluding that these drugs are not effective. Men become more relaxed and confident the more times they use the drugs.
  • The best time to have sex is one to two hours after taking the drugs. That is when the drug is most distributed in the blood system.
  • When the timing is right to have sex after taking the drug, direct penile stimulation is necessary. The drug works by preventing the breakdown of a molecule that is responsible for creating an erection, which is only released when there is sexual stimulation.

Insertion therapy

A small soft pellet containing alprostadil (MUSE) can be inserted into the tip of the penis and the penis massaged gently to release the medication. This can result in an erection. Some possible side effects are burning, penile pain and urethral bleeding. This route of administration is not as effective as that of injection therapy of the same drug.

Penile injection therapy

This is an effective (70% - 80% effective) method of achieving an erection and is used when oral medications do not work. Alprostadil (Caverject) can be injected into the side of the penis and an erection usually occurs within 5 to 15 minutes. The first injection should be given under direct medical supervision to ensure the correct technique and dosing. The dosing can be adjusted by the patient so that priapism (prolonged erection) does not occur. Other medications can be mixed with alprostadil if it is not effective or is too painful. These mixtures are ‘bimix’ (alprostadil plus phentolamine) and ‘trimix’ (alprostadil, phentolamine and papaverine) and can be prepared in approved pharmacies.

The side effects of injection therapy are:

  • Priapism (prolonged erection) – see below.
  • Penile pain is more common when alprostadil is used.
  • Penile scarring:
    • Repeated injection over the same site can result in local scarring and fibrotic changes resulting in curvature of the penis (Peyronie’s disease).
    • This is more common when papaverine is used.
    • Bruising can happen if an inadvertent injection into a penile blood vessel occurs. It is also more common in patients on blood-thinning medications.

Some patients should not have injection therapy because their pre-existing medical conditions can predispose them to priapism (see below). Some of these medical conditions are:

  • Sickle cell anaemia.
  • Multiple myeloma.
  • Leukaemia.

Vacuum erection device

The device is a cylinder that is placed over the penis to create a seal and by extracting air from the cylinder, a vacuum is created. An erection then ensues – a rubber constriction ring is rolled over the cylinder onto the base of the penis to maintain the erection after the cylinder is removed. This technique requires practice and sometimes assistance from the partner. It is effective in creating an erection, but penile sensation may be altered, and the penis may pivot at the ring. Ejaculation (but not orgasm) is restricted by the ring.

Penile prosthesis implantation

If earlier approaches fail or are inappropriate, then penile prosthesis implantation surgery can be considered as a last resort. The success rate is high (about 85%). Two inflatable cylinders are implanted into the shaft of the penis, together with a pump in the scrotum and a fluid reservoir in the lower abdomen. When an erection is required, the patient squeezes on the pump to inflate the cylinders. Possible complications are infection and mechanical failure. Semi-rigid malleable rods can also be implanted but tend to be less acceptable to patients when compared to inflatable prostheses because they are less cosmetic and physiological.

Penile Prosthesis

What is priapism?

A prolonged erection (> 4 hours) that does not go away despite conscious attempts by the patient is called priapism. Most cases of priapism are ‘low-flow’ and caused by the inability of the penile blood to drain back to the body, usually as a result of over-effective ED treatment. All patients on ED treatments should be aware of this possible complication and it is considered a ‘medical emergency’. Patients should present to the emergency department for further treatment.

‘Low-flow’ priapism is painful and can cause scarring of the penile tissue, compromising further erectile function.

‘High-flow’ priapism is less common and is usually caused by previous penile trauma. The trauma caused the formation of a connection between inflow and outflow blood vessels in the penis. When the inflow is more than the outflow, priapism occurs. This is less painful as compared to ‘low-flow’ priapism. Treatment involves the radiological placement of a small substance to block off the abnormal blood vessel connection.

Related information

Read A/Prof Gani’s publication:
Download Do patients know their nerve sparing status after radical prostatectomy - PDF (115 Kb)

Read A/Prof Gani’s publication:
Download Management of erectile dysfunction in patients with sickle cell disease - PDF (453 Kb)