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If you have any familiarity with the Salem Witch Trials, you already know something about mass hysteria, also known as mass psychogenic illness.

Mass hysteria refers to an outbreak of unusual and uncharacteristic behaviors, thoughts and feelings, or health symptoms shared among a group of people.

People affected by mass hysteria:

  • typically believe something specific has triggered their symptoms
  • don’t have an underlying health condition that could prompt those symptoms
  • wouldn’t behave in that way on a regular basis
  • may share an extreme fear of an exaggerated or nonexistent threat

Beyond the events in colonial Salem, Massachusetts, plenty of historical examples of mass hysteria exist. Yet this phenomenon still happens in the present day, fueled partly by the internet and social media. Still, there’s a good bit of confusion around what it involves.

Below, you’ll find an in-depth explanation of this 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.

People commonly use the term “mass hysteria” to describe a rapid spread of panic and fear. But the actual 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.

In terms of sociology, it falls into the category of collective behavior, or the mostly spontaneous actions of a large group of people who influence each other.

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 usually spreads verbally and visually. So, people who see or hear about someone with symptoms often begin experiencing symptoms themselves.

Some experts use the term more loosely to describe any episodes of collective fear around a threat that doesn’t actually exist.

Here’s an example:

  • News reports and social media posts begin speculating about bioterrorism or a harmful substance in the community.
  • These frequent reports trigger widespread anxiety and concern in people following the updates, even when no proof supports the existence of any real danger.
  • You could start to experience symptoms “caused” by the threat — especially if you hear others have those same symptoms.

Examples of mass hysteria

A few historical and present-day examples include:

  • 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 more accurately fall into the category of a collective panic since it didn’t cause the kinds of symptoms typically seen with mass hysteria.

With mass hysteria, symptoms are very real, even though no actual threat or health condition triggers them. That’s a large part of why experts consider it a type of conversion disorder.

Mass anxiety hysteria generally involves physical symptoms like:

Mass motor hysteria more often involves symptoms like:

  • shaking and twitching
  • partial paralysis
  • unstoppable laughing or crying
  • trance-like states
  • altered speech patterns

Signs of mass hysteria can also involve symptoms associated with a specific feared threat.

Maybe a few people in a community believe they were exposed to a toxic chemical. They might suddenly begin to notice rashes, breathing difficulties, muscle tremors, and other symptoms they’d experience after actual exposure to that chemical. Any other community members who witness these symptoms might then develop the same symptoms themselves.

While experts don’t know for certain what causes mass psychogenic illness, a few potential theories have emerged.

Extreme anxiety and stress

Both present-day evidence and theories about historical occurrences of mass hysteria suggest stress and anxiety play a part.

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.

Examples of potential triggers include:

  • a strict school environment, especially a school away from home
  • a community grief or disaster
  • tense school relationships, particularly during puberty
  • an isolated community, particularly one that follows a strict religious faith and punishes any deviation
  • a pandemic or other 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. Soon, more students who went on the same trip develop the symptoms. Since you went on the trip too, you know it’s just a matter of time before you notice symptoms yourself

Sure enough, a few days later you notice a small patch of discolored, itchy skin on your wrist. “It’s beginning,” you think with dread. You start to notice specks of light at the corner of your vision and wait with some trepidation for the dizziness and confusion to begin.

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‘Stage fright’

This theory may help explain symptoms that develop in response to sudden stress.

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.

No official treatment for mass psychogenic illness exists.

Conversion disorder often improves with therapy, combined with reassurance and compassionate acknowledgment of symptoms. Experts generally recommend addressing instances of mass hysteria with a similar approach.

In a nutshell, identifying and taking steps to resolve the underlying source of stress will generally help relieve any physical symptoms you experience.

A trained therapist won’t tell you the symptoms are “all in your head.” They’ll offer guidance with recognizing possible sources of stress and anxiety contributing to those symptoms. Therapy also offers a safe space to learn and practice new methods for coping with ongoing stress in your life.

Another important step toward recovery? Distancing yourself from the epicenter. Getting some space from other people reporting or discussing the shared symptoms can help you find a sense of calm that promotes a faster recovery.

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.

Scientific evidence has yet to fully explain mass psychogenic illness, but experts do generally agree it can happen to anyone, especially in times of turbulence, major stress, or emotional upheaval.

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 writes for Healthline and Psych Central. Her fields of interest include Japanese translation, cooking, natural sciences, sex positivity, and mental health, along with books, books, and more books. In particular, she’s committed to helping decrease stigma around mental health issues. She lives in Washington with her son and a lovably recalcitrant cat.