Medical Research into Efficacy & Safety

Over the past few years, numerous clinical studies have been conducted into the effectiveness of non-surgical penile enlargement through the use of traction.

Below is a summary of this medical research data:

Tractive Elongation of the Penis by Means of Stretching – Sienna 1998

This medical study undertaken by Jørn Ege Siana, MD, a Danish plastic surgeon and Urologist (specialist in problems affecting the male genitalia) was published and presented to International Interdisciplinary Symposium on Genitourinary Reconstructive Surgery in April 1998.

The study charted the effectiveness of penile traction on 18 test subjects ranging from 23-47 years of age, all of whom presented with normal erectile capacity and who had undergone no previous penile surgery.

Each patient employed the use of a traction device for a total of 1100 hours over the course of 26 weeks, with medical follow up every 2 weeks.

The traction force employed was 0-2 weeks = 900-1000g; 2-24 weeks = 1000-1200g using a type 1 medical penile traction device.

Key Results:

Patients achieved an overall average increase of 29% in erect penis length.
1100 hours of treatment equated to an average increase in erect length of 2.8 cm (1.1 inch)
Average erect lengthening per week was 1.9 mm
In percentage terms, patients achieved an average erect length increase of 13% following 8 weeks treatment, 19% following 16 weeks, 24% following 20 weeks and finally 29% following the final 26th week.
Erect length increase for patients with an average starting erect length of 6.4 inches equates to 1.86 inches (8.26 inch erect penis length following treatment).
All patients achieved penile lengthening.
No reported complications.

Penile Enlargement Without Surgery - Gomez de Diego et al 2001

Scientific data presented to the Sexology and Sexual Education Congress in February 2001 by a Spanish Urologist, Dr Eduardo A. Gomez de Diego records similar results to the above study.

The research involved a larger test group of 37 healthy men with normal erectile function ranging in age from 22 to 60 years. None of the subjects had undergone any type of penile surgery.

Each patient used a Type 1 medical penile traction device over a period of six months. The traction force applied was: 0-4 weeks = 600g, 4-8 weeks = 900g, 8– 6 weeks = 1100g, 16-24 weeks = 1200g

Key Results:

Average erect length increase after 1 month was 0.4726 cm, whilst average flaccid increase was 0.4834 cm
Average erect length increase after 3 months was 1.4118 cm, with a minimum growth rate of 1.1522 cm
Average erect length increase after 4 months was 1.8462 cm, with a minimum growth rate of 1.5809 cm
Average erect length increase after 5 months was 2.2750 cm, with a minimum growth rate of 1.7656 cm
Average erect length increase after 6 months was 3.3333 cm, with a minimum growth rate of 2.8162 cm
Over the course of 6 months treatment, patients on average achieved a 27.5% increase in erect penis length.
The average circumference (girth) increase was 0.81 cm in erect girth and 0.84 cm in flaccid girth.

The research concluded with the following statement:

"The use of traction will increase the length of the penis, both in erected and flaccid state. The increase in length, both in erection and flaccidity, is directly proportional to the time of use. The increase in length both in erection and flaccidity does not depend on the natural size of the patient’s penis."

The researchers also noted that gains had no relation to patient age (all experienced similar results) and that contrary to popular belief, the use of a penile traction device also promoted gains in penis girth (providing an average gain of 0.81 cm in erect girth).

Efficacy of the daily penis-stretching technique to elongate the “Small Penis” – Colpi et al – 2002

Researchers from San Paolo Hospital, Milan, Italy presented the findings of the above titled study to the Congress of the European Society for Sexual and Impotence Research (ESSIR) in Hamburg, Germany in 2002. The research paper was published in the International Journal for Impotence Research in the same year.

Researchers studied the effective of penile traction on 9 subjects from the ages of 26 – 43, who suffered from penis size anxiety, although all fell within medically average size ranges. Hence the study's use of the term "small penis" referred to the patients' perceived belief that their penises were abnormally small.

In this medical study, each subject employed the use of a Type 1 medical penis traction device for 6 hours a day, over the course of 4 months.

Key Results:

After completion of 4 months treatment patients experienced an average increase of 1.8 cm in stretched penile length (equivalent to an erect length measurement)
Patients who employed traction for time periods in excess of the average 6 hour usage achieved more prominent length increases. Erect length increases of between 2.4 and 3.1 cm were achieved where patients used the device for between 7 and 9 hours.
No complications or negative side effects were reported.

The study concluded by stating that increases in penis length were therefore proportional to the total length of time the device was worn. In other words, the longer each subject wore the device per day, the greater the gains he achieved.

Effects on Penile Size with Penile Extensor by Traction Force – Z Lee et al 2005

Medics from Institute of Andrology, Renji Hospital, Shanghai, conducted a 3 month clinical trial involving 30 men between 16 and 40 years of age, to study the safety and efficacy of penile traction.

The study employed a more aggressive traction regime whereby patients were instructed to wear a penile traction device for 9 hours per day over the course of the 3 month treatment.

Key Results:

Following 3 months treatment, patients experienced an average erect penis length increase of 2 cm and a flaccid length increase of 2.1 cm
The study also recorded an average increase in erect circumference of 1.9 cm, with an average flaccid circumference increase of 1.8 cm
The report recorded an 'effectiveness rate of 100%' in test subjects
No reported complications
Results were again, stated to be proportionate to daily wearing time.

The report concluded that, "The penis extender has the capability to stretch the penis and produce a significant increase in both penile length and width. Furthermore, the treatment has been demonstrated to be safe and free from adverse side effects."

Summary of Clinical Research Data

Clinical research has validated the claim that penile traction offers an effective and safe method of non-surgical penis enlargement. With continued daily usage over a period of 3 – 6 months, subjects achieve on average a gain in erect penis length of between 26 – 29 percent. For a man possessing a starting erect length of the 6.4 inches (Kinsey study average), he can therefore expect to achieve an increase of between 1.664 and 1.856 inches over this time frame.

The above research also clarifies that modest gains in penile circumference (girth) are also achieved – although these are not as pronounced as length increases. Gomez de Diego 2001 reports average circumference increases of approximately 0.8 cm, whilst Z Lee reports significantly higher increases of approximately 1.8cm. This dispels the notion that penile traction produces gains in length at the expense of girth. The discrepancy between the two studies is in all likelihood explained through the more aggressive traction regime employed by Z Lee et al.

All studies point to the fact that gains are directly proportional to the total number of hours that traction is employed through the entire course of treatment. In other words, the same gains will ultimately be achieved through the employment of traction for 3 hours a day over 6 month as could be accomplished through a more aggressive regime of 6 hours per day over 3 months. It is the total combined number of hours wearing time that equates to the final increase.

In addition to its efficacy, the above research also points to the safety of traction – noting that no complications were reported in any of the test subjects. Therefore it would seen that traction offers a viable method of non-surgical penis enlargement, that over a moderate time frame of 3 – 6 months can produce gains that fulfil the expectations of patients in a safe and controlled manner.

The above studies all relied upon the use of medically certified 'Type 1 Medical' traction devices – of which there are only two models presently available to the general public – the Pro Extender and Size Genetics Device. You'll find further information about the importance of only using such a device on the Type 1 Medical Devices page of this website.

Type 1 Medical Devices - An introduction to the types of devices used in the above medical trials.

Product Comparisons - A closer look at the two leading devices: SizeGenetics and Pro Extender. The only penis traction devices to have been certified as 'Type 1 Medical Devices' and to have undergone extensive clinical research.