The Dancing Plague – Mysterious Illness Made People Dance To Death

Could Food Have Caused It?

One of the most famous explanations involves ergot, a fungus that grows on grains such as rye.

Ergot produces powerful chemicals derived from ergot alkaloids, including compounds related to LSD. When contaminated grain is consumed in sufficient quantities, it can cause ergotism, a severe form of poisoning.

The symptoms can be horrifying.

Convulsive ergotism causes violent muscle spasms, tremors, seizures and involuntary movements. People may also experience hallucinations, confusion and intense psychological disturbances. Another form can restrict blood flow to the limbs, causing tissue death and gangrene.

Medieval Europe experienced documented outbreaks of ergotism, particularly in periods when contaminated grain entered the food supply. A 2025 historical discussion of ergotism highlighted how familiar these outbreaks were in medieval Europe and how closely several reported symptoms—convulsions, hallucinations and gangrene—fit descriptions associated with the disease.

At first glance, ergot seems like the perfect explanation for Strasbourg.

People were hungry. Rye was an important food source. Contaminated grain could produce neurological symptoms capable of causing uncontrollable movements.

But there is a problem.