Following is a list of some of the major factors that are responsible for causing majority of the cases of the curved penis.
Peyronie’s disease: The most common cause for a curved penis is Peyronie’s disease. Peyronie´s is a degenerative disease, if left untreated it will continue to get worse. The most common result of this disease is an increasingly curved penis, sometimes to the extent that it makes sexual intercourse painful or impossible.
Curvature present at birth: Birth (congenital) curvature, as the names indicates, is present at birth or it can also occur somewhere in the first couple of weeks after birth. While such deformation of penis usually corrects itself without any treatment in most cases, it persists in some cases i.e. the penis curve usually gets more pronounced (or becomes noticeable at first place) in the time of the puberty. This is because male intimate organ grows much faster in this period of your life due to the secretion of sex hormones i.e. testosterone. Sometimes the flaw is just aesthetic but for some, it can severely impede a normal sex life, making sex difficult, painful, or even impossible.
Mechanical injury: Many men, who are not born with a curved penis, can develop one later on in life as a result of trauma inflicted on the penis or even on scrotum. In some cases, it has been observed that a direct mechanical injury / trauma to the scrotum (testes) eventually led to the development of penile curvature. This means, although the penis or scrotum / testes obviously have no bones inside it, this kind of trauma can still cause permanent damage. Sex-related accidents, even those you would not think twice about after they happen, can cause ruptures inside the penis which stunt growth. When the penis is hurt in this way, it often causes one side of the penis to stop growing. While the healthy side outgrows the damaged side, the penis will effectively become curved.
Tight clothing & spontaneous erections: The way penis is worn in pants during puberty period and the spontaneous erections have an important impact on the overall size and shape of the penis. For example, when males (who wear very tight underwear or pants) get erections, their penile tissue becomes restricted and, to some extent, immobilized. In addition, they often curve their penises over to the side to hide the awkward erection. This affects the enlargement because blood will flow better through one side of the spongy tissue and while leaving the other side undernourished depriving it of oxygen and other important nutrients.
Masturbation: It has been now shown in several studies that the way one masturbates in early periods of life i.e. in adolescence and before onset of puberty has a profound impact on overall sex drive and size and shape of the genitals. Different theories have been proposed to justify the same. For example, according to some researchers, continuously masturbating in the same position can lead to curvature development. Also, if uses only one hand or does it in odd position, it could also lead to curvature.
Sleeping pattern / position: Some sexperts and reproductive experts ask adolescents to refrain from sleeping on their belly i.e. stomach. The hypothesis is that sleeping on your stomach, especially in puberty, when erections occur during the sleep and penis is still growing has a “compression” effect on the blood vessels of the penis and it naturally results in a reduced blood to the spongy tissues of the penis.
This eventually leads to the reduced growth of the tissue of the penis, often on one side and hence results in the formation of curvature. Also, based on the same theory, even grown-up adults could have the same issue depending on how they are built and how big pressure is at penis during the night sleep. For example, fatter or obese people have stomach to hold them up and it does not really compress their penis like the way it does in thin people or those with normal physique. Nevertheless, it is recommended not to sleep on your belly because of several other health reasons as well.
Miscellaneous causes: There are some other causes that can lead to the formation of curve in the penis. These commonly include:
Dupuytren’s contracture: This is a cord-like thickening across the palm of one or both hands. It is a fairly common disorder in white men over age 50. However, only a very small number of people with Dupuytren’s contracture develop curvature of the penis.
Urethral obstruction: Obstruction of urethera (the small tube that carries the urine and semen to and out of the penis).