Sometimes people in a group start to think they might have been exposed to something dangerous, like a germ or a toxin (poison). They might get signs of sickness like headache, dizziness, faintness, weakness or a choking feeling. If many people in the group start to feel sick at about the same time, we might think they have mass psychogenic illness. The group might be a class in a school or workers in an office. Mass psychogenic illness is sometimes called mass hysteria or epidemic hysteria.

Is mass psychogenic illness common?

Mass psychogenic illness has been talked about and written about for hundreds of years, all around the world and in many different social settings. No one keeps track of these outbreaks, but they are probably a lot more common than we realize.

How do these outbreaks start?

Many outbreaks of mass psychogenic illness start with an environmental “trigger,” like a bad smell or a rumor of exposure to a poison. When one person gets sick, others in the group also start feeling sick. The first person who got sick might have had a real illness, but it might not have been related to the “trigger.”

How do the symptoms spread?

An outbreak of mass psychogenic illness is a time of anxiety and worry. Reporters are paying attention to the situation, and rumors are spreading. Ambulances and emergency workers are making people think a serious epidemic is happening. At such a time, if you hear about someone getting sick or if you see someone get sick, it may be enough to make you feel sick too.

Does this mean that the sickness is “all in my head”?

No, it doesn't. The people who are in these outbreaks have real signs of sickness that are not “imagined.” They really do have headaches, or they really do feel dizzy. But their illness is not caused by a poison or a germ.

Then why did I feel sick?

Outbreaks of mass psychogenic illness show us the powerful effect of stress and other people on the way we feel. Think of how “stage fright” can cause nausea, shortness of breath, headache, dizziness, a racing heart, a stomachache or even diarrhea. Your body can have a similar strong reaction to the stressful situations involved in mass psychogenic illness.

Does this mean there is something wrong with my mind?

No. These outbreaks happen to normal, healthy people. Just because you reacted this way to a mass illness does not mean there is something wrong with your mind.

How do we know an outbreak of sickness is caused by “mass psychogenic illness”?

We might think a group sickness is caused by mass psychogenic illness if:

• Physical exams and tests are normal.

• Doctors can't find anything wrong with the group's classroom or office, like some kind of poison in the air.

• Many people get sick.

If we look at the patterns of the outbreak (like the kinds of illnesses that are reported, the kinds of people who are affected, the way the illness spread) we might think mass psychogenic illness is the reason.

How can we stop these outbreaks?

Most of these outbreaks stop when people get away from the place where the illness started. The illness tends to go away once people are examined and doctors tell them that they do not have a dangerous illness. Keeping the people who feel sick away from all the commotion and stress is important.

After experts check out the place where the outbreak started, they can reassure people that it is safe to go back to that place. You should see your doctor to be checked for a different reason for your health problem if:

• Your illness seems to last several days.

• You have a fever.

• Your muscles are twitching.

• Tears keep coming from your eyes.

• Your skin feels like it has been burned.