Penis enlargement, sometimes called male enhancement, refers to an assortment of techniques intended to increase the girth, length, or erectile rigidity of the human penis.
Procedures range from manual exercises to stretching devices and surgical procedures, with reports of successes and failures around the world. While some techniques are known to be outright hoaxes, others can produce some measure of success. Often, in the advertising of fraudulent products, the distinction between temporary enlargement, i.e. erection, and permanent enlargement is deliberately muddied.
Little legitimate scientific research has been done specifically on the subject of non-surgical penile enlargement; existing claims of significant and permanent enlargement are generally anecdotal, unverified by objective research, and can be biased by the interests and emotions of the source. At present, there is no proof of any non-surgical technique that permanently increases either the thickness or length of a normal penis. Some general research has been done regarding the safety and efficacy (or lack thereof) of the ingredients of various pharmaceutical or quasi-pharmaceutical preparations, but thus far, nothing has emerged to cause mainstream medicine to adopt any of them. There are also risks inherent in some of the more invasive procedures, with negative outcomes ranging from the tearing of skin and scarring, to permanent loss of sexual function. Due to the speculative nature of any hope for “improvement”, social controversy due to the sexual nature of the topic, and the many known cases of permanent injury involved in the endeavor, many medical professionals are sceptical of the subject, and tend to avoid work in this field.
Much of the marketing of commercial penis-enlarging treatments is based on unproven assertions that a larger penis enhances sexual prowess and general attractiveness to potential mates. Enlargement of a normal penis is distinguished from seeking relief from the recognized medical condition of micropenis, where surgery to increase the organ's size is sometimes needed for urinary or sexual purposes. Anxiety about the size of one's penis may be (in extreme cases) a psychological/psychiatric condition best dealt with by qualified medical practitioners.
There are several surgical treatments, all carrying a risk of significant complications. The Second International Consultation on Sexual Dysfunctions concluded,
Most men will not wish to proceed to surgery when properly informed of the likely outcome and risks of complications.
Procedures by unlicensed surgeons can lead to serious complications.
Penis enlargement pills, patches, and ointments are commonly offered over the Internet. While some products contain harmless ingredients, many are entirely untested for safety and side effects, and none of these products has been demonstrated effective.
A variety of physical therapy techniques have been used in an attempt to enlarge the human penis. Generally, the techniques involve stretching, elongation by the use of small weights, or increasing the bloodflow and/or blood pressure in the penis. There is also significant overlap between techniques intended to enlarge the penis and techniques intended to achieve other, related objectives, such as reversing impotence, extending the duration of erections, or enhancing sexual climax.
A penis pump is a cylinder that is fitted over the penis, with a manual or motorized pump to create a partial vacuum around the penis, engorging it as blood is drawn in. A variety of penis pump designs have been adopted by penis pump manufacturers. As vacuum increases, the pressure within the blood vessels of the penis increases as well; excessive vacuum causes vascular damage. Penis pumps may be used to temporarily overcome symptoms of impotence, but do not cure the condition: a tourniquet-like ring must be applied to keep the blood trapped within the penis, otherwise the erection will immediately subside. Pumps may work even if there is nerve or vascular damage preventing a natural erection, but excessive or prolonged use (hours) will cause permanent harm as over-enthusiastic pumping can burst blood vessels and form blisters.
The effectiveness of penis pumps for permanent penis enlargement was examined by Kazem, Hosseini and Alizadeh. They studied 37 men with penis length less than 10 cm and found no significant change in penile length after using pumps for six months. The efficacy of vacuum treatment was approximately 10%, and the patient satisfaction rate was 30%. The conclusion of the paper stated that vacuum treatment of the penis is not an effective method for penile elongation, but provides psychological satisfaction for some men.
In the US, penis pumps may be covered by Medicare if they are deemed medically necessary. Pumps have been used to successfully treat men with Peyronie's disease, which causes unusual shortening and curvature of the penis. A 31-patient study conducted by the Department of Urology at St Peter's Hospitals and the Institute of Urology in London found, “clinically and statistically significant improvement in penile length, angle of curvature, and pain after 12 weeks of vacuum pump use”. In this study, subjects with Peyronie's undertook two ten-minute pumping sessions per day for twelve weeks. The additional penis length, an average of 0.5 centimetres (0.20 in) was an unexpected side effect found in approximately one third of the subjects and not an intended aim of the study.
Clamping is a risky and dangerous technique. The goal of clamping is to increase the size of the penis using a constricting device, such as a shoe string, cable clamp, or a tight cock ring to restrict blood flow out of the organ. The device is firmly attached at the base of the erect penis, and the man engages in “edging” (extended masturbation). A metal cock ring is dangerous because blood trapped in the penis can make removal of the ring impossible without emergency intervention such as amputation or sawing the ring off. Clamping can cause permanent catastrophic damage to the penis.
Jelqing is a physical-therapy technique, intended to achieve “natural penis enlargement” by increasing blood pressure and circulation. It is performed by repeatedly stroking the penis in a squeezing motion from the base of the shaft to the corona of the glans; devices have also been created to achieve this same effect. The motion may be described as “milking“.
According to an article in BJUI, the technique has ancient Arabian origins; and an Arabic word related to “milking” is sometimes claimed as the etymological root of the term, although this point is disputed and the actual origin of the term remains unclear.
While there are many anecdotal claims of success from supporters of the technique, there is no medical evidence for its effectiveness. Furthermore, medical journalist Christopher Wanjek has said that the claim that the technique will “enlarge the penile cavities that fill with blood, making for larger erections…makes no sense biologically.” Similarly, Sue Johanson explains jelqing cannot possibly enlarge the penis, though it is unlikely to cause any serious damage.
Although considered safer than many other, more “radical” techniques for penis-enlargement, jelqing could potentially result in blood vessel tearing, scar formation, pain, disfigurement, and desensitization of the penis if done incorrectly.
Traction is a nonsurgical method to lengthen the penis is by employing devices that pull at the glans of the penis for extended periods of time. As of 2013, the majority of research investigates the use of penile traction focuses on treating the curvature and shrinkage of the penis as a result of Peyronie's disease, although some literature exists on the impact on men with short penises 
Traction as a penis-enlargement method stems from the observation that issues under continuous tension will undergo cellular multiplication. The result is tissue expansion, resulting in a permanent increase of the tissue. Many forms of body modification employ this principle. Whether effective or not, excessive tension can result in injury to the tissues or nerves of the penis.
The 2013 meta-analysis by Doctors Chung and Brock concludes that many current studies show promising evidence for small to moderate permanent penis lengthening by traction, and, contrary to the claims of many manufacturers, no evidence of change in penis circumference. Chung and Brock also highlight the difficulty in controlling such studies, the lack of random selection of patients, and the potential for selection bias due to the high requirements of patient conformity and motivation. Modern studies have not yet determined the optimum time or traction force, the variance in penis enlargement among patients using similar time or force, or how diligently patients must utilize the traction device to gain results.
In Vietnam, many Vietnamese men attempted self penis enlargement by injecting liquid silicone into their penises, and subsequently suffered from complications such as infections, necrosis, tumors, swelling, and other deformities, losing the ability to have sex, and had to be hospitalized.
Phapluatvn.vn (July 15, 2014). “Self improvement penis silicone injections, 40 villages to rescue boy”. DBV – Đọc Báo Việt. Retrieved July 14, 2014.