Penis shrinkage can occur and is often due to age, medication side effects, or lifestyle habits, such as smoking or weight gain. It rarely requires treatment, and habit changes can often help.

Penis size can vary significantly between people, and certain lifestyle factors can affect it.

This article discusses the current research on average penis sizes, what may cause shrinkage, and available treatment options.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Research into average penis sizes is often impaired by inaccurate participant reporting, selection bias, and inadequate sample sizes. However, a 2020 review calculated that the average penis size was:

  • Erect: 13.61 cm (5.36 inches)
  • Flaccid, pulled: 12.98 cm (5.11 inches)

Older but more detailed research from BJU International found average penis size falls within the following ranges:

  • Average length of a flaccid penis: 9.16 centimeters (3.6 inches)
  • Average length of a flaccid stretched penis: 13.24 cm (5.3 inches)
  • Average length of an erect penis: 13.12 cm (5.2 inches)
  • Average circumference of a flaccid penis: 9.31cm (3.7 inches)
  • Average circumference of an erect penis: 11.66 cm (4.6 inches)

Penis shrinkage is widespread as men age, but there are many other reasons why a penis may shrink:


As people age, several bodily changes can impact penis function, especially the reaching and maintaining of erections. Notably, muscle cells in the erectile tubes inside the penis can weaken with age. The erectile tubes produce erections when engorged with blood, so less blood flow means smaller or fewer firm erections.

Furthermore, fatty deposits can build up in the arteries (atherosclerosis), causing reduced blood flow to the penis, and a natural reduction in testosterone can further decrease erection size and strength.

Learn more about erectile dysfunction and aging here.

Weight gain

Weight gain, particularly around the stomach, may also impact perceived penis size.

Although a penis may appear smaller with weight gain, it has not shrunk. It looks smaller because the penis is attached to the abdominal wall, and when the belly expands, it pulls the penis inward. If a person loses weight, his penis will regain its shape and size.

Prostate surgery

Research from 2014 found that penis shrinkage occurred in 15–68% of patients after cancerous prostate gland removal surgery (radical prostatectomy) may experience some penis shrinkage.

However, more recent reviews note that penile shrinkage rates tend to lessen the further on from surgery recovery a person gets. Researchers found that around 60% of patients regained full penis length at 12 months of recovery.

Peyronie’s disease

In Peyronie’s disease, fibrous scar tissue develops inside the penis, causing it to become curved during erection. Most of the time, a curved erection is not a reason for concern, but for some, the bend might be significant or painful.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Peyronie’s affects up to 23% of natal males ages 40 to 70.

Peyronie’s can cause a reduction in the length and circumference of a penis. Sometimes, Peyronie’s goes away on its own; most of the time, however, it will either stay the same or worsen.


Studies have found penile shrinkage and other sexual dysfunctions to be a side effect of finasteride, a common anti-baldness medication.

Some medications can also reduce blood flow to the penis, and affect sexual performance, including the strength and size of erections. These medicines include anti-hypertensives and selective serotonin reuptake inhibitors.


Limited research suggests a correlation between smoking and below-average penis size. However, further controlled studies are necessary to investigate this potential link fully.

Smoking is also associated with erectile dysfunction (ED), according to a 2017 study.

Chemicals from cigarette smoking can injure the blood vessels in the penis, preventing the penis from filling with blood and stretching. Regardless of the stimuli and the effect on the brain, if the blood vessels are damaged, the penis will not achieve an erection.

Most causes of penis shrinkage, such as smoking and weight gain, can be addressed by lifestyle changes. If medications are causing the penis to shrink, a medication adjustment can reverse the shrinkage.

For some men who experience penis shrinkage after prostate removal, the condition may improve on its own within a few months to a year. Penile rehabilitation (a form of physical therapy) after surgery can help men regain erectile function, and medications, such as Viagra and Cialis, can boost blood flow to the penis.

Treatment for Peyronie’s disease focuses on removing scar tissue from inside the penis, either with medication, surgery, or ultrasound technology. Penis shrinkage is irreversible but repairing the curvature can help improve sexual function and reduce pain.

Most of the time, penis shrinkage is related to age, medication, or lifestyle habits, such as smoking or weight gain, and rarely requires treatment. Adopting more healthful lifestyle habits or changing medication can often reverse shrinkage and reduce other sexual problems.

Any person who is experiencing penis shrinkage, pain, or other sexual problems, or has concerns about cancer, should talk with their doctor. A doctor or urologist, can answer questions, reassure patients, and offer testing and treatment if necessary.