What are the three worms in Taoist internal alchemy called?

The three worms in Taoist internal alchemy are called San Chong.

San Chong is the pinyin romanization of the Chinese term 三蟲, literally “Three Worms.” In Daoist religious physiology, these were imagined as supernatural parasites living inside the human body from birth. They occupied the three dantian, or energy centers, associated with the head, chest, and abdomen.

The worms were believed to cause illness, weaken their host, and encourage morally harmful behavior. A related belief held that they reported a person’s wrongdoing to celestial authorities during the gengshen nights of the traditional sexagenary cycle, shortening the offender’s lifespan. Daoist practitioners therefore used fasting, meditation, ritual, and longevity techniques to expel or control them.

A common source of confusion is that the same beings are also called the “Three Corpses,” or Sanshi. That name uses different Chinese characters and emphasizes their connection with death rather than their wormlike nature. San Hun is unrelated: hun refers to the ethereal souls in traditional Chinese thought.