Stages of an Erection

April 11, 2024
4 mins

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What is an Erection? 

An erection is a physiological response in males characterized by the stiffening and enlargement of the penis. This occurs when blood flow to the penis increases, causing the spongy tissues within the penis to fill with blood and become engorged. 

Erections can be triggered by physical stimulation – such as touch or arousal – or they can occur spontaneously during sleep, known as nocturnal penile tumescence. Erections are a normal and natural part of male sexual arousal and are essential for sexual intercourse and reproduction.

What are Stages of an Erection? 

The process of achieving an erection involves several stages, including:


The first stage of an erection begins with sexual arousal, which can be triggered by physical or psychological stimuli. 

Before stimulation, the penis is soft – or flaccid. 

The arousal leads to the release of neurotransmitters that signal the blood vessels in the penis to dilate, increasing blood flow to the erectile tissues.


As blood flow to the penis increases, the erectile tissues – known as the corpora cavernosa and corpus spongiosum – become engorged with blood, causing the penis to swell and stiffen. 

This expansion or swelling is referred to as tumescence. It creates pressure on the veins that normally carry blood out of the penis, helping to trap blood within the erectile tissues and maintain the erection.

Full erection

In the final stage, the penis reaches its full size and hardness, resulting in a rigid erection, allowing for penetration during sexual intercourse. The erection is sustained by a balance of blood flow into and out of the penis, regulated by the constriction of blood vessels and the activity of smooth muscle tissue within the erectile tissues.


After sexual arousal diminishes or ejaculation occurs, the erection gradually subsides as blood flow to the penis decreases. This process – known as detumescence – typically occurs gradually but can be accelerated by various factors such as physical activity or distraction. The penis returns to its soft, flaccid state, marking the end of the arousal cycle.

These stages of an erection are regulated by a complex interplay of hormonal, neurological, and vascular factors, and any disruption in this process can lead to erectile dysfunction.

Types of Erections

Surprisingly enough, there are different types of erections, each with distinct characteristics and underlying mechanisms. 

Psychogenic erection

Psychogenic erections are triggered by sexual arousal or stimulation – whether it's physical or mental. 

They typically occur in response to erotic thoughts, images, or sensations. Psychogenic erections involve the release of neurotransmitters that stimulate blood flow to the penis, leading to engorgement and rigidity.

Nocturnal penile tumescence (NPT)

Nocturnal penile tumescence, also known as "morning wood," refers to erections that occur spontaneously during sleep, particularly during the rapid eye movement (REM) stage of the sleep cycle. 

NPT is a normal physiological process and is not necessarily associated with sexual arousal. It is believed to be related to changes in hormonal levels during sleep and may serve a physiological function in maintaining penile health.

Reflexogenic erection

Reflexogenic erections are triggered by physical stimulation of the genitals – such as touch or friction. 

This is the type of erection that usually occurs before sex or during foreplay. That being said, it’s possible to achieve a reflexogenic erection without purposefully arousing the penis.

Unlike psychogenic erections, which involve higher brain centers and conscious arousal, reflexogenic erections occur in response to direct stimulation of the penis or surrounding genital area. They can occur during sexual activity or as a result of non-sexual touch or pressure.

Spontaneous erection

Spontaneous erections occur without any apparent external stimuli or conscious arousal. These erections can occur randomly and unpredictably throughout the day, often during periods of relaxation or when the individual is not engaged in sexual activity or stimulation. 

Spontaneous erections are more common during puberty and tend to decrease with age.

Erections During Puberty 

During puberty, the body undergoes significant hormonal changes that impact various aspects of development, including sexual maturation. 

One notable aspect of sexual development during puberty is the onset of erections in young men. Erections typically begin to occur during early to mid-puberty, usually around the ages of 10 to 14, although this can vary widely among individuals.

The initiation of erections during puberty is primarily driven by hormonal changes, particularly the increase in testosterone production. Testosterone is the primary male sex hormone responsible for stimulating the development of secondary sexual characteristics – including the growth of facial and body hair, deepening of the voice, and the development of the male reproductive system. 

As testosterone levels rise during puberty, it triggers physiological changes in the genitals, leading to the ability to achieve erections.

Erections during puberty can occur spontaneously and unpredictably, often without any direct sexual stimulation. This randomness of erections is a common experience for adolescent males and is largely attributed to the fluctuating levels of hormones and the increased sensitivity of the genitalia during this developmental stage. 

Factors such as physical activity, emotional arousal, or even changes in body temperature can also trigger erections during puberty.

It's important to note that while erections during puberty may sometimes occur in embarrassing or inconvenient situations, they are a normal and natural part of sexual development. 

They serve as indicators of healthy physiological functioning and are not necessarily indicative of sexual arousal or intent. 

Additionally, the ability to achieve and maintain erections during puberty is an essential milestone in the development of sexual function and reproductive capability.

How Hard is a Normal Erection?

The hardness of a normal erection can vary from person to person and can also depend on various factors such as age, overall health, level of arousal, and individual anatomy. Generally, a healthy erection should feel firm and rigid enough for penetration during sexual intercourse, but it should not be excessively rigid or painful.

In medical terms, the hardness of an erection is often assessed using a scale called the Erection Hardness Score (EHS), which ranges from 0 to 4:

  • Grade 0: Penis is completely flaccid with no evidence of erection.

  • Grade 1: Penis is larger but not hard.

  • Grade 2: Penis is hard but not completely rigid. It can be bent but not easily.

  • Grade 3: Penis is hard and fully rigid. It can be bent slightly with difficulty.

  • Grade 4: Penis is completely hard and fully rigid, with no ability to bend.

A normal erection typically falls within the range of Grade 3 or Grade 4 on the EHS, indicating sufficient rigidity for sexual activity. However, it's important to note that the perception of hardness can be subjective, and what feels normal for one person may differ for another.

If an erection feels consistently softer than usual or if there are concerns about erectile function, it may be advisable to consult a healthcare professional for further evaluation and guidance. 

Erectile dysfunction (difficulty achieving or maintaining an erection) can be caused by various factors, including underlying health conditions, medications, stress, or psychological factors, and may require medical attention.

How Long Does an Erection Usually Last? 

The duration of an erection can vary widely depending on factors such as level of arousal, individual physiology, and external stimuli. 

In general, a healthy erection typically lasts anywhere from a few minutes to around 30 minutes on average, although some erections may persist for longer periods in certain circumstances.

During sexual arousal, blood flow to the penis increases, causing it to become erect. Once sexual stimulation ceases or ejaculation occurs, blood flow gradually decreases, and the erection subsides. This process usually occurs naturally and can take anywhere from a few minutes to half an hour to complete.

It's important to note that the duration of an erection is influenced by various factors, including the individual's age, overall health, level of sexual arousal, and any underlying medical conditions. 

Prolonged erections lasting more than four hours – a condition known as priapism – can be a medical emergency and may require immediate medical attention to prevent complications such as tissue damage and erectile dysfunction.

Medications to Help Achieve an Erection

If you’re looking for a solution to help you with ED, Rex MD has got you covered.

PDE5 inhibitors are a class of medications that help relax muscles in the penile arteries and promote blood flow, which often leads to an erection. Some examples of PDE5 inhibitors are Viagra and Cialis – both of which have proven to be highly effective.

Rex MD helps guys in need of an extra boost in the bedroom get ED medications like Viagra and Cialis. If you qualify, the meds will be sent directly to your doorstep. The best part is that it all happens quickly and discreetly and you won’t have to even leave your house. 

Get started today.

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