"Koro” is an Indonesian word meaning “shrinkage”, which accurately describes what people fear when they have genital retraction syndrome, as it’s called in the Western world.
People with this syndrome have an overpowering belief that their penis (though, it has been known to occur in women with the case of breasts) is retracting and will eventually disappear into their body. This syndrome has even led to epidemics, which have affected hundreds of people at a time and caused mass public hysteria and panic. Although reports of the syndrome are most prominent in Asian countries, it has been known to occur in people from around the world.
In China, koro is thought to be caused by evil female fox spirits and is characterised by the overwhelming state of panic or anxiety experienced by its sufferers. While it is physiologically possible for the volume of the penis to temporarily decrease when it’s cold or when its owner is extremely stressed (this is called vasoconstriction), Chinese culture holds that koro is prolonged and leads to the loss of sexual power, impotence and eventually death. They see it as a reduction in the male’s “yang” — which disturbs the harmonic, life-sustaining equilibrium of yin-yang. This is not ideal at all from their standpoint, and so sufferers are hastily treated with traditional Chinese medicines. Similar superstitions regarding koro are held by various cultures worldwide.
Even though many people believe genital retraction will eventually result in death, sufferers have actually died trying to stop this from happening by resorting to some pretty gruesome measures. Men have been known to anchor themselves to clamping devices, and women have inserted iron pins into their nipples in an attempt to stop their supposed retreat. Even if these measures didn’t kill the sufferers, they always caused severe physical injury, bruising or infection.
Researchers don’t yet know the exact cause of koro. Personality and psychosexual history may play a role, but it’s interesting to note that the syndrome tends to be most common in cultures where reproductive ability is a highly valued marker of a person’s worth.