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Causes of Erectile Dysfunction

What Is the Erectile Process?

To understand what causes erectile dysfunction (ED) or impotence, it is important to first review how an erection occurs. For a man to have an erection, a complex process takes place within the body. Erectile dysfunction is a term related to male sexual dysfunction and will be the only subject covered in this article.

  • Sexual dysfunction includes problems with sexual interest (libido), erectile problems, orgasmic problems, and ejaculatory problems. ED is one component of sexual dysfunction and may occur by itself or in association with other sexual dysfunctions.
  • An erection is a "neurovascular event" meaning that in order to have an erection there needs to be proper function of nerves, arteries, and veins. An erection involves the central nervous system, the peripheral nervous system, physiologic and psychological factors, local factors with the erection bodies or the penis itself, as well as hormonal and vascular (blood flow or circulation) components. The penile portion of the process leading to an erection represents only a single component of a very complex process.
  • Erections occur in response to touch, smell, auditory, and visual stimuli that trigger pathways in the brain. Information travels from the brain to the nerve centers at the base of the spine, where primary nerve fibers connect to the penis and regulate blood flow during erections and afterward.
  • The penis is composed of three cylinders: two on the top, the corpora cavernosa and one on the bottom, the corpus spongiosum. Only the corpora cavernosa are involved in the process of an erection. The corpora cavernosa are composed of potential spaces that can distend with blood, muscle, and blood vessels. When aroused, stimulated chemicals are released from the nervous system (nitric oxide is one) that stimulate the arteries to the penis to relax and increase blood flow into the penis. These potential spaces, like a sponge, can expand when more blood flow comes in the penis. Each corpora cavernosa is surrounded by an outer coating the tunica albuginea. When the penis fills with blood, these potential spaces, the sinusoids, compress the veins in the corpora against the side of the tunica albuginea, thus preventing blood from leaving the penis. It is this compression of the veins that allows for the erection to become fully rigid.
  • Erections occur in response to touch, smell, auditory, and visual stimuli that trigger pathways in the brain. Information travels from the brain to the nerve centers at the base of the spine, where primary nerve fibers connect to the penis and regulate blood flow during erections and afterward.
  • Detumescence (the process by which the penis becomes flaccid) results when muscle-relaxing chemicals are no longer released. The muscles contract, blood flow to the penis decreases, and the sinusoids get smaller, allowing blood to drain from the penis.

If one or more of the above physical and/or psychological processes is disrupted, erectile dysfunction can result. Erectile dysfunction (ED)/impotence is defined as the inability to achieve and maintain an erection that is satisfactory for the completion of sexual activity.

In general, the cause of erectile dysfunction is divided into two types. Many men will have both

  • psychological (mental) causes and
  • physical or organic (having to do with a bodily organ or an organ system) causes.

The normal erection process.
The normal erection process. Click to view larger image.

Medically Reviewed by a Doctor on 4/5/2017
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Patient Comments & Reviews

The eMedicineHealth doctors ask about Causes of Erectile Dysfunction:

Erectile Dysfunction - Causes

Please describe the cause of your ED.

Erectile Dysfunction Medications

In addition to taking medications to treat erectile dysfunction, it is important to make lifestyle changes that may alter the underlying cause of erectile dysfunction. Such changes include:

  • improving eating habits,
  • quitting tobacco and alcohol products, and/or
  • getting regular exercise.

Some doctors may prescribe more than one medication, depending on a patient's response and ability to tolerate the various medications.


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