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Erectile Dysfunction (ED)

Last Updated: Mar 1, 2019


Erectile dysfunction (ED) is a sexual disorder where a man is not able to get or maintain an erection for sexual intercourse. An estimated 30 million men in the United States are affected by ED, also referred to as “impotence.” Although the risk of ED increases with age, the natural process of aging is not the cause.

The process of forming an erection begins when a man experiences sensory or mental stimulation, which sends signals from the brain to nerves in the penis. These impulses relax local muscles, allowing a rush of blood that expands the penis to a full erection. A normal erection lasts until after sexual climax, when local muscles contract to stop blood inflow. Loss of function at any of these steps can lead to ED.

ED can cause social/emotional anxiety and have a negative impact on intimacy. Additionally, it poses a challenge for partners trying to become pregnant. It is critical to discuss ED with a physician in case it is a symptom of an underlying medical condition, such as heart disease and diabetes.  Depending on the cause, a variety of treatment options are available.

Causes and Risk Factors

ED is caused by a range of emotional, psychological and physical conditions that affect the normal process of achieving an erection. In some instances, multiple factors are involved. Physical conditions can cause ED by damaging the nerves, muscles, arteries and fibrous tissues involved in an erection, while psychological/emotional factors interfere with the initial sensory stage of arousal. Sometimes the anxiety associated with ED exacerbates the condition.

Physical Causes

  • Diseases of the heart and blood vessels
  • High blood pressure
  • Plaque buildup in the arteries (atherosclerosis)
  • Diabetes
  • High cholesterol
  • Kidney disease
  • Nervous system disorders (e.g., Parkinson’s disease, multiple sclerosis)
  • Scar tissue formation in the penis (Peyronie’s disease)
  • Low levels of male hormone testosterone

Psychological Causes

Risk Factors

  • Age: Although age is associated with ED (over 50% of men with ED are age 60 or older), the process of aging is not a factor.
  • Medical conditions: Diseases of the nervous system, kidneys and heart are linked to ED.
  • Medications: Drugs used to treat depression, allergies, ulcers and high blood pressure increase the risk of ED.
  • Smoking: Tobacco use reduces the body’s overall blood flow and can lead to ED.
  • Injury: Prostate cancer treatments and other trauma to the penis, pelvis and spinal cord can cause ED.
  • Sports: Activities that restrict blood flow to the penis (e.g., bicycling) are associated with ED.
  • Obesity: High body weight increases the likelihood of a variety of other medical condition, including ED.
  • Drugs/alcohol: Prolonged use of alcohol and drugs increases the risk of ED.
  • Psychological disorders: Stress, depression and other mental disorders typically have a negative effect on arousal.


The symptoms of ED include:

  • Difficulty having and/or maintaining an erection
  • Low sexual desire.

Diagnosis and Treatment

Physicians diagnose ED by performing a physical exam and questioning the patient about their symptoms. The following tests may be performed to identify the cause of ED:

  • Blood/urine tests: These tests measure proteins associated with testosterone, diabetes, heart disease and other health conditions.
  • Physical exam: A physical exam of the penis and testicles looks for signs of nerve damage or physical injury.
  • Ultrasound: This technique uses sound waves to produce an image of the veins carrying blood to the penis.
  • Erection test: This test keeps track of the number and strength of erections men experience during nighttime sleep.
  • Psychological evaluation: This exam uses a series of questions to identify anxiety, depression and other psychological causes of ED.

Lifestyle changed can often remedy ED and restore sexual function back to normal. These include avoiding tobacco, drugs and alcohol, and improving physical fitness. Additionally, receiving proper therapy for anxiety, depression and other psychological triggers of ED is important.

If ED is the result of a health condition, such as diabetes or heart disease, then therapy is focused on treating those conditions. Patients who develop ED due to prescription medication can talk to their doctors about alternative medications. Therapies specifically targeting ED include drugs, pumps and surgery (as a last resort).

  • Oral drugs: Oral drugs like sildenafil (Viagra®) and tadalafil (Cialis®) help men get an erection by enhancing blood flow to the penis. These drugs cannot cause an erection automatically; the initial sexual stimulation is still required.
  • Injectable/suppository: The drug alprostadil also acts by improving blood flow to the penis. It can be delivered via injection to the base or side of the penis. Alternatively, it can be delivered via a small suppository applicator through the penile urethra.
  • Hormone therapy: Hormone replacement therapy is used in men who develop ED as a result of low levels of the male hormone, testosterone.
  • Pumps: Hand- or battery-powered pumps force blood to the penis by vacuum action. Once placed over the penis, the pump draws out the air from inside the tube, leaving a vacuum that draws blood into the penis. A tension ring at the base of the penis holds the blood in the penis to maintain the erection.
  • Implants: Inflatable or semirigid rods are surgically placed along both sides of the penis to allow manual control of an erection.
  • Surgery: ED caused by leaking or obstructed blood vessels is treated by surgical techniques, such as vascular stenting or bypass.


Regular exercise and mental health welfare are effective ways of preventing the lifestyle causes of ED. It is also important to limit alcohol and avoid drugs and tobacco.


  • “Erectile dysfunction”. Mayo Clinic. Retrieved Apr. 11, 2016.
  • “Erectile dysfunction”. The National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved Apr. 11, 2016.
  • “Erectile dysfunction”. MedlinePlus (National Institutes of Health; NIH). Retrieved Apr. 11, 2016.

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.