Koro (disease)

Koro is a delusional disorder tied to specific cultural contexts, where a person becomes convinced that their genitals are shrinking and will vanish, even though no lasting physical changes are actually happening. It’s sometimes called “shrinking penis” and was listed in the DSM-IV-TR Glossary of Culture-Bound Syndromes, though it was never included as a formal disorder in the main text of any DSM edition. The condition appears around the world, and episodes of mass hysteria about genital shrinkage have been recorded in Africa, Asia, and Europe. The term comes from Malay, meaning the head of a turtle or tortoise—a reference to how these animals pull their heads back into their shells.

People with koro typically experience intense anxiety attacks because they feel their genitals are retracting or shrinking, even when there’s no visible, long-term change. “Longstanding” here means changes that persist over time and aren’t reversible, unlike the temporary shrinkage caused by cold. An attack can be triggered by noticing such temporary changes. Episodes usually last a few hours but can stretch to two days; in some cases, symptoms persist for years, which may point to an overlap with body dysmorphic disorder. Besides retraction, patients might perceive a change in penis shape or loss of muscle tone. Some report a sensation of numbness or shortening without actual retraction. In women, the main symptom is a feeling that the breasts or labia are retracting or shrinking.

The anxiety often includes a fear of death, of the penis dissolving, or of losing sexual ability. In Chinese traditional beliefs, there’s a strong cultural link between these fears and the idea that koro is fatal—a view more common in Asia than in the West. Other fears can involve internal organs shrinking, turning into a woman or eunuch, physical danger, blocked urination, sterility, madness, spirit possession, or being bewitched. To stop the perceived retraction, patients or their families may use physical methods like pulling on the penis by hand or with a string or clamp. Women might grab their breasts, pull their nipples, or even insert pins into them. These attempts can cause injury, sometimes fatal.

Psychosexual conflicts, personality traits, and cultural beliefs are thought to play a role in causing koro.