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Mass hysteria, also known as mass psychogenic illness, is a topic that you already know about.

Mass hysteria is an outbreak of unusual and uncharacteristic behaviors, thoughts and feelings among a group of people.

People affected by mass hysteria.

  • They believe something specific has triggered their symptoms.
  • “Don’t have an underlying health condition that could cause those symptoms.”
  • “wouldn’t do that on a regular basis”
  • It is possible that you share an extreme fear of a threat.

There are many examples of mass hysteria beyond the events in Salem. The internet and social media are to blame for this phenomenon still happening today. There is a lot of confusion around what it involves.

There is an in-depth explanation of the phenomenon, including types of mass hysteria, the main signs, and suggested causes.

Language matters

The term “hysteria” once applied to a wide variety of mental and physical health symptoms experienced by women. This broad “diagnosis” was sometimes used as a reason to hospitalize women with no actual health concerns — often without their consent — in facilities where they faced harsh treatment.

The third edition of the “Diagnostic and Statistical Manual of Mental Disorders (DSM-III),” published in 1980, removed hysteria as a diagnosis, and experts no longer use this term.

That’s not to say you shouldn’t use the term, but it’s worth keeping its history in mind.

Mass hysteria is a term used to describe a rapid spread of fear. The definition is a bit more complex.

Experts largely consider mass hysteria a type of conversion disorder, or mental health condition that involves physical symptoms prompted by emotional or mental tension.

It falls into the category of collective behavior, or the mostly random actions of a large group of people who influence each other, in terms of sociology.

Many experts recognize two distinct types:

  • Mass anxiety hysteria. This typetends to show up among people who belong to the same close, often isolated, group or community. It involves sudden tension and other symptoms of anxiety, which “spread” and resolve fairly quickly.
  • Mass motor hysteria. This type tends to show up among people experiencing long-term stress and tension. It involves irregular motor (movement) symptoms that move from person to person gradually and often linger for weeks.

Mass hysteria spreads in many ways. People who hear about someone with a symptom start to experience their own symptoms.

“Some experts use the term more casually to describe any fear that doesn’t exist.”

Here is an example.

  • News reports and social media posts start to speculate about bioterrorism or a harmful substance in the community.
  • People are concerned and anxious when there is frequent reports of real danger, even if no proof is present.
  • If you hear others have the same symptoms, you could start to experience them.

Examples of mass hysteria

There are a few historical and present-day examples.

  • Choreomania. In the Middle Ages, groups of people across Europe began to dance spontaneously, without stopping, until they dropped from exhaustion. Some historians link this dancing plague to a fear of St. Vitus, believed to have the ability to make people dance.
  • Hand and arm tremors in students. In the late 1800s, students in a number of girls’ schools across Europe experienced unusual symptoms, including tremors, shaking, convulsions, uncontrollable laughter, and even amnesia. These symptoms first began in just a few students but were soon experienced by others. They only appeared in specific classes, or only during the school day, and didn’t affect students at other times.
  • Vaccine side effects. In 1998, 800 children in Jordan became ill with what they assumed were side effects of the tetanus-diphtheria vaccination they’d received at school. Over 100 of the children went to the hospital for treatment, but healthcare professionals eventually determined that most of them hadn’t experienced any reaction to the vaccine.
  • Tics. In 2011, a few high school girls in Leroy, New York, began to experience a number of motor symptoms, including muscle twitches, facial tics, and altered speech. Before long, others developed the same symptoms. Something similar happened again in 2020 and 2021, when people around the world (mainly girls and women) began to show vocal and motor tic-like behaviors — mostly after watching TikTok videos of people living with tic and movement disorders.

Some people have even suggested the widespread alarm around COVID-19 constitutes a type of mass hysteria, though COVID-19 presents an actual, serious health threat.

“Extreme fear of COVID-19 along with related stockpiling of medications, household essentials, and food would be more accurately described as a collective panic since it didn’t cause the kinds of symptoms typically seen with mass hysteria.”

Even though no threat or health condition can cause mass hysteria, symptoms are still real. That is a big part of why experts consider it a conversion disorder.

Mass anxiety hysteria can involve physical symptoms.

Symptoms of mass motor hysteria include:

  • shaking and twitching
  • partial paralysis
  • unstoppable laughing or crying
  • It was like a trance-like state.
  • Speech patterns have been altered.

Mass hysteria can also include symptoms associated with a specific threat.

Maybe a few people in the community were exposed to a toxic chemical. They might experience symptoms after exposure to that chemical, such as breathing difficulties, muscle tremors, and rashes. The same symptoms might be developed by any other community members who witness them.

There are a few theories that have emerged about what causes mass psychogenic illness.

Extreme anxiety and stress

Evidence and theories show that stress and anxiety are part of mass hysteria.

Some evidence suggests mass motor hysteria tends to result from ongoing stress, while mass anxiety hysteria more commonly develops in response to sudden, extreme stress. Not all experts make this distinction, though they do largely accept that both ongoing and sudden emotional distress play a role.

Potential Triggers include:

  • A school away from home is a strict environment.
  • A community or disaster.
  • tense school relationships
  • An isolated community that follows a strict religious faith and punishes any deviation.
  • A threat that poses a risk of major health consequences.

The nocebo effect

Experiencing the placebo effect from a medication or treatment means you feel better because you expect the treatment to work.

With the nocebo effect, however, you might develop unwanted symptoms or reactions because you expect to experience them.


Several classmates who went on a spring break trip develop a rash, dizzy spells, and episodes of confusion. Students who went on the same trip will develop symptoms. You know it is just a matter of time before you notice symptoms of your own.

You notice a small patch of discolored skin on your wrist a few days later. You think with dread that it is beginning. You start to notice light at the corner of your vision and you are afraid of the dizziness and confusion that will come with it.

‘Stage fright’

This theory may help explain how stress can cause symptoms.

Knowing you have to do something you don’t particularly want to do can cause feelings of stress and worry. This tension can then lead to actual physical symptoms of anxiety. In some cases, these symptoms might even offer an unconscious method of dodging the overwhelming situation or feared event.

Of course, that only explains your symptoms. But others facing a similar challenge or ordeal, like classmates or other community members, might be dealing with the same tension.

There is no official treatment for mass psychogenic illness.

Therapy and reassurance can improve conversion disorder. Experts recommend addressing mass hysteria with a similar approach.

Taking steps to resolve the underlying source of stress will help relieve physical symptoms.

“A therapist won’t tell you the symptoms are all in your head. They will offer guidance with regards to possible sources of stress and anxiety. Therapy can be used to learn and practice new methods for dealing with stress in your life.”

Another important step in the recovery process? Ignoring the epicenter. Getting some space from other people can help you find a sense of calm that will help you recover quicker.

This doesn’t just involve physical separation from other people with symptoms. It also means avoiding related news stories and social media posts or videos of people experiencing similar effects. Social media and the internet will often only intensify your anxiety and physical symptoms.

Experts agree that mass psychogenic illness can happen to anyone, even in times of turbulence, major stress, or emotional upheaval, despite the fact that scientific evidence has yet to fully explain it.

Without a doubt, living through crisis after crisis can fuel the very tension that often lies behind mass hysteria. That’s what makes it so essential to seek support for overwhelming or persistent anxiety and take other steps to protect your emotional and physical well-being.

Reducing stress in your life can help lower your chances of experiencing any psychological response to extreme emotional turmoil.

Crystal Raypole is a writer for Healthline. Her interests include Japanese translation, cooking, natural sciences, sex positivity, and mental health. She is committed to helping decrease stigma around mental health issues. She lives in Washington with her son and cat.