Updated: 2021, May 13

An In-Depth Report On Erectile Dysfunction

What is erectile dysfunction? Learn what causes ED, how to treat erectile dysfunction, how ED medication works.


Erectile dysfunction (ED), otherwise known as impotence, is the inability of males to obtain or maintain a penile erection during sexual activity [1,2].

An In-Depth Report On Erectile Dysfunction
Erectile dysfunction is the inability to achieve or sustain an erection suitable for sexual intercourse. Shutterstock Images

There are many reasons why a man would suffer from Erectile dysfunction.

These issues can also arise at any time in a man’s lifetime and if not well understood can lead to many unnecessary problems which could have been averted.

Erectile dysfunction (ED) can cause problems that vary from marital and relationship breakdown, poor self-esteem and social withdrawal.

In the USA, its overall incidence in males aged 40-69 is about 18% and a study in the UK suggests the rate of diagnosis is increasing (see Figure 1).3,4

Rate of Diagnosis

Figure-1: Graphical representation of increased rate of diagnosis of ED over a ten year perios from 1990. Graph based on data reported by Kaye and Jick, 2003.4

This increase in the number of diagnoses probably reflects more confidence and willingness of sufferers to report their condition to their physician.

The increase noticed in these years seems to have plateaued.3

As well as its detrimental psychological impact on self-esteem and relationships, there is growing evidence that the disorder can increase the risk of adverse coronary events at least in individuals already with relevant risk factors [5,6].

Of equal importance, as will be discussed herein, ED can actually be an early marker (indicator) of far more serious problems such as heart disease and, indeed, certain types of brain tumor called pituitary adenomas.


*All individuals are unique. Your results can and will vary.

The latter relationship could well not be even considered by general practitioners but is very important since failure to diagnose such tumors early can lead to other serious effects due to extensive expansion (growth) of the brain lesion.

This article will review the physiology, causes, and treatment of ED.

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Normal and Abnormal Physiology of Penile Erection

Male erection is a result of blood entering into and being maintained by soft tissues (corpora carvenosa) within the penis (Figure 2).7

Corpora Carvenosa

Figure 2. Soft areas of the penis, the corpora carvernosa, become engorged with pressurisied blood causing an erection.

Physically, it is actually a hydraulic effect i.e. a response to a liquid under pressure in a confined area.

Erection involves interplay between the brain, CNS and blood vessels. That is, nerve signals from the brain lead to increased blood flow in vessels within the penis.

Although usually initiated by sexual arousal, this is not always the case.

For example, males often experience erections during sleep and in the early morning.

ED, or impotence, is the partial or complete failure of the erection mechanism during sexual activity.1,2 Note, somewhat paradoxically, night-time and early morning erections are still achieved by many subjects suffering ED.6

Causes of ED

The most obvious risk factor is age (Figure 3).8 Although it can occur at any age, about 50% and 70% of men between 40 – 70 and above 70 are affected, respectively (Figure 3).


*All individuals are unique. Your results can and will vary.

Broad reasons account for this observation.

With increasing age, blood vessels tend to become constricted thus limiting blood flow to the penis.

In addition, and not surprisingly, the risk of disease and the necessity of medications are increasingly likely with advancing age.

Indeed, ED is now considered a diagnostic marker for coronary disease.9

Number of Men Suffering

Figure-3: Increasing trend for number of men suffering from some form of ED with age.

The specific causes of ED include the following:

  • Psychological
  • Side effects of medications
  • Alcohol use and dependence
  • Obesity
  • Hormonal disturbances

Secondary to other diseases such as:

  • Diabetes
  • Coronary disease
  • Arteriosclerosis
  • Parkinsons
  • Peyronie’s disease (scar tissue in the penis)
  • Smoking
  • Physical
  • Injury or surgery to the pelvic region
  • Compression events e.g. cycling
Causes of ED

Erectile dysfunction can be caused by anything from cardiovascular disease, diabetes, psychological problems, hormone imbalance & medication side effects

All of these can, in one way or another, diminish blood flow to the penis.

Psychological factors, in the complete absence of other reasons for ED, is surprisingly common.6,10 Once anxiety about performance sets in, achieving erection can be very difficult.

Consistent failure only exacerbates anxiety.

It might be thought that the presence of night-time and morning erections in such subjects is indicative that the ED must be psychological.

In fact, this is not completely correct since subjects whose ED is linked to coronary disease may still experience morning erections.9

Nevertheless, the occurrence of morning/night-time erections in ED subjects, whether psychologically caused or not, does indicate that penile erectile structures are still intact.

ED is often a side effect of medications for high blood pressure and depression.3,4


*All individuals are unique. Your results can and will vary.

Blood pressure medications include beta-blockers, calcium channel inhibitors and angiotensin-converting-enzyme (ACE) inhibitors.

All of these are designed to reduce blood pressure so it is hardly surprising they can reduce blood flow to the penis.

Antidepressants classed as selective serotonin reuptake inhibitors (SSRIs) are also commonly associated with ED, although the detrimental effect may pass with time.11

Alcohol is a depressant and acutely reduces blood pressure.

Alcohol use and dependence is often associated with ED and there is a clear-cut direct relationship between amount consumed and failure to achieve erection.12

Several endocrine disturbances can lead to ED.

Lowered levels of the male sex hormone, testosterone, due to hypogonadism (underactivity of the testes which are the source of testosterone) is correlated to erection difficulties and lack of sexual arousal.8

Hypogonadism has several different causes, one of which is over-production of prolactin (hyperprolactinaemia).13

Too much prolactin interferes with the ability of the testes to produce testosterone leading to male infertility and, sometimes, ED.

Hyperprolactinaemia has several causes including drug medication such as metoclopramide (an anti-nausea medication) and, indeed, SSRIs mentioned earlier.

This may explain why SSRIs are linked to ED.

Another cause is a tumor of the pituitary gland, which hangs down from the base of the brain and is the source of prolactin.

These are called prolactinomas.

Significantly, ED is often the first sign of a prolactinoma in males but it is not recognized as such because it is believed the sexual underperformance is due to something else.

The tumor, remaining undiagnosed, grows quite large and begins to press on other areas of the brain causing serious defects such as abnormalities in vision and severe headaches.

Other types of pituitary tumour can also cause.14,15

These include a type that produces too much of a hormone called ACTH.

The excess ACTH makes the adrenal glands release far too much cortisol and leads to a syndrome called Cushing’s disease associated with obesity, tiredness, and diabetes all of which can cause ED.

Still another type of pituitary tumor, called functionless, prevents normal hormone production leading to decreased testosterone, the male sex hormone that helps libido.

As a man gets older, levels of testosterone naturally decrease and this accounts, at least in part, for the observed increase in ED rates with age.13

Of the other causes of ED mentioned above, Polyneuropathies is a factor.

Polyneuropathies are diseases and/or conditions that affect the nerves in the penis such as diabetes, alcohol and chemotherapy drugs.

Another reason is the pressure effect of cycling is becoming more and more recognized as a relevant risk factor.17

A long term bicycle ride exerts lasting pressure to the perineum, between the anus and base of the penis in the pelvic area.

This pressure leads to constriction of blood vessels and impaired nerve function.

It seems that some thought must be given to saddle design, riding styles and bicycle mechanics to help ensure a more comfortable ride.

In fact, a so called ‘lady’s saddle’, which has an open area near the middle, allows a space for the perineum to sit inside thus avoiding the pressure (Figure 4).

Bicycle Ride

Figure 4. Bicycles with a hollow recess, in which the perineum can be accomadated, help prevent compression of blood vessels and nerves supplying the penis.

Peyronie’s disease is due to the growth of connective tissue (that is, tissues that hold other cells together) in soft penile regions.

The condition causes discomfort, penile curvature, loss of thickness and ED.18

Unfortunately, it is difficult to rectify although many cases improve with time.

Clinical Presentation

It is important to take a proper history from the patient.

This will give many important clues as to where the problem lies, whether there are reversible causes which can be dealt with conservatively and if the problem is of such a nature that specialist referral is required.

Patient History:

The following questions are asked of the patient:

  • Strength of erection? The patient can point out on 4 different rubber sponges, each with a different firmness. The softest represents a grade 1 weak erection (10-30% firmness), the next sponge represents a grade 2 erection (30-60% firmness), the following sponge represents a grade 3 erection (60-90% firmness) and the last and firmest sponge represents a normal, full erection.
  • Do you lose your erection while having intercourse?
  • Do you struggle to get an erection for intercourse?
  • Have you used any prescription or over-the-counter medication for this problem?
  • How are your morning erections? If they are also weak, then that could possibly point to a neurological problem.
  • Are there any problems with your erections when masturbating? If the patient is having weak erections when having intercourse but normal erections when masturbating, then there could be psychosocial or psychiatric issues affecting the erection.
  • Past and current sexual partners and current relationship status
  • Previous and current emotional status
  • Past medical history including chronic illnesses and medications? This is probably the most important question as this will give you the clue as to where the main cause of the weak erection lies.
  • Past surgical histories such as procedures involving the genitals, prostate or vascular system (conditions as mentioned above)
  • Family history of prostate or testicular cancer
  • Any allergies?
  • Social habits such as smoking, illicit drug use and/or alcohol consumption

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Physical Examination:

Once the patient has been interviewed, the next step is to perform a physical examination.

In most cases, patients will give a normal history where there’s no indication of what the cause of the weak erection is.

The examination of this patient will then help to unmask any undiagnosed issues that have been the cause all along.

The following examinations are performed on the patient:

  • The general appearance of the patient will give a lot of clues. Is the patient very skinny or obese? Is he pale or does he have a yellow tinge of the skin?
  • Vitals such as pulse and blood pressure are important.
  • Examination of the abdomen.
  • Examination of the genitals including the testicles and scrotum, penis and foreskin and looking at how the distribution of pubic hair occurs.
  • Rectal exam to feel the prostate in all men over 50 years old and, if there’s a family history of prostate cancer, then in men over 40 years of age.

Special Investigations:

There are many tests that can be done in order to assess whether a patient is diabetic, has a low testosterone count or has an underactive thyroid.

These can be divided into tests that can be done at the office (side-room investigations) and tests that need to be sent to a laboratory to be investigated.

The tests are requested based on the doctor’s findings during the interview and examination of the patient.

Specific tests will also be suggested if it is felt that the patient will need a specialist urologist to see him.

Side Room Investigations:

  • Glucose finger-prick test – this will check your sugar levels. A preferable sample is a fasting one where the patient hasn’t eaten or drunk anything for 10 hours.
  • Urine dipstick test – a urine sample is taken and tested to see if there are any abnormalities such as signs of infection or kidney disease.

Laboratory Tests:

  • Blood can be drawn from the patient and checked for thyroid, cholesterol or testosterone issues. Blood for prostate specific antigen (PSA) levels should be done in the abovementioned patients and the blood should not be drawn immediately after performing a rectal exam as this could produce falsely elevated levels.
  • If testosterone levels are decreased, then further tests need to be done in order to determine if the reason for the low level is either due to an issue in the hormone gland (pituitary) in the brain or in the testicles.

Specialist Investigations:
In the unlikely event that the reason for the weak erection is still not found, then further specialist referral is warranted.

A psychologist can be consulted to deal with any psychosocial or intimacy issues the patient would be dealing with.

This is usually done together with the patient’s partner once they have been seen alone by the healthcare professional.

A psychiatrist can see a patient if the cause of the weak erection is due to resistant psychiatric illnesses that don’t respond to adequate treatment.

A patient can also be referred to see a urologist if blood results warrant it or in order to request specialist investigations, such as the following:

  • Nocturnal penile tumescence.
  • Rigidity studies.
  • Vascular studies such as duplex ultrasound of the cavernous arteries, treatment with intracavernous vasoactive drug injection, dynamic infusion cavernosography or internal pudendal arteriography.

Specialists such as neurologists or endocrine physicians can also be consulted if the cause of the weak erection falls under the field of these specialties.

Treatment of ED

In cases where ED is secondary to another disease, such as endocrine disorders, then correction of those disorders may well eliminate the sexual problems.

Likewise, improvements in life style such as weight loss, avoidance of excess alcohol and smoking, eating healthily and so on may all greatly help persons suffering ED.

However, clearly these approaches will be ineffective in many subjects with disease and, indeed, medication for diseases, as mentioned, maybe the actual cause of ED. Fortunately, there are a number of treatment options and new ones are also being developed.

If the ED has an unequivocal psychological cause, then counselling, cognitive behavioural therapy (CBT) or sensate focus may successfully alleviate the problem [18].

Sensate focus, developed by Masters and Johnson, is a therapy carried out by couples together.

Both agree to abstain from sex for several weeks. Only non-sexual touching is permitted.

During the intimate time couples explore each other through massage, light stroking etc but there should be no intention of full intercourse.

After a few weeks, erogenous areas (genitals, breasts) are explored, but still with no intention of full sex.

The couple spends a few sessions doing this with increased sexual contact, for example, using mouth to mouth or mouth to body touch.

Eventually, anxiety about ED will disappear and full sexual intercourse becomes possible.

CBT is individual based therapy and based on helping the patient realize and understand that the ED is created in the mind.

Avoiding negative thoughts is the goal of such therapy.

Like sensate focus, psychosexual counseling is for couples together where a discussion of what might be the deep-rooted reason for the ED, in terms of the relationship, can be discussed and may be resolved.

If these methods fail, or if the reason for ED is something other than psychological, other treatments are available.

Of great media, interest is the phosphodiesterase inhibitors (Sildenafil, Cialis, and Levitra are common brands).

Cells in the corpus carvenosa (to soft tissue of the penis) contain an enzyme called phosphodiesterase type 5 (PDE5) which causes breakdown of a chemical called cGMP [4].

cGMP causes blood vessel dilation, allowing more blood to flow into the penis.

Thus, by inhibiting the PDE5, high levels of cGMP are maintained and better blood flow to the penis is facilitated.

Although PDE5 inhibitors are very efficacious, they do not work for all subjects with ED and / or are contraindicated for medical reasons such as heart disease so another method may be necessary.

A physical method is the use of a vacuum pump.

To create an erection, a plastic cylinder is placed over the penis and the air in the cylinder is pumped out making a vacuum.

This vacuum forces blood to flow into the penis.

Another possibility is an injection of a drug called Alprostadil directly into the penis.

Alprostadil is actually a type of fatty acid called prostaglandin and causes blood vessel dilation, like PDE5 inhibitors.

This method is highly effective but some might be put off by the thought of putting a needle into the penis.

An alternative delivery method is to place the Alprostadil into the urethra as a dissolvable pellet (commercially known as Muse) although this has lower success rates.

If low testosterone is confirmed, then a patch impregnated with the hormone can be applied to the skin.

The hormone is slowly released and enters the body perhaps leading to improvements in sexual performance.

A recent newly available treatment is a cream called Vitaros.

In fact, this cream is a new formulation of Alprostadil and come with a syringe to allow application directly into the urethra.

How well this new formulation acts will be determined in the near future.

An interesting idea is to use pelvic floor muscle exercises.19 Beneficial to woman (exercises known as Kegels) for prolapse and improving sexual feeling, it is becoming clear that they help male sexual satisfaction as well.

The exercises involve contracting and relaxing the same muscles that can stop the flow of urine during micturition.

Rapidly and repeatedly contracting and releasing the muscles in combination with contracting and holding the muscles for 10-second bursts are recommended.

The method is reported to solve ED in up to 40% of cases.19

In fact, these investigators suggest that the exercises should be a first line, non-invasive and non-medical treatment.

Finally, and perhaps the last resort in case of other treatments failures, surgical implants are also possible.

One type of implant is actually a pump which is activated to make an erect penis.

The other option is a malleable prosthesis. Risks for these ED implant treatments include infection and malfunction.

Read Also:: Depression Due To Erectile Dysfunction


ED occurs in a surprisingly large proportion of males of all ages, but especially from middle age onwards.

The symptoms should not be ignored because they might be indicative of serious underlying disease.

In cases where changes in lifestyle are not relevant, a large variety of other treatment options are available such as psychotherapy, counseling, medications, and surgery.

Research continues and new therapies will become available in the future.

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Dr. Elmari Craig, PhD

Dr. Elmari Mulder Craig is the Past President and Director of The Southern African Sexual Health Association (SASHA).

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