Sympathetic vomiting occurs when the sight, sound or smell of a person vomiting causes others to become nauseated and throw up. It is a fairly common occurrence among humans, and some scientists and experts consider it an evolved trait in primates. Sympathetic vomiting may seem like a simple reaction to an unpleasant sight or smell, but it may actually be rooted in survival strategy.
Vomiting can be caused by a variety of physical problems, including dyspepsia, indigestion, food allergies, or poisoning. The act of throwing up is caused when the contents of the stomach are forcefully swept up through the body, being expelled through the nose and mouth. People stricken with vomiting may experience heart palpitations and sweating, and reoccurring bouts of nausea. Excessive vomiting can also lead to severe dehydration, particularly if the body is not able to keep any food or liquid down.
The smell of vomit is widely considered to be one of the worst in the world, and may induce nausea in anyone nearby. While this may be simply a reaction to a malodorous aroma, it is possible that the body has a subconscious reaction to the smell or sight of the vomit itself. Because of the possibility that something the sick person has consumed has made them ill or poisoned them, your body may chemically decide to rid itself of potentially poisoned contents as well. In groups of apes, group or sympathetic vomiting has been observed after one animal becomes ill after eating. Since the other animals in the tribe have likely eaten the same things, sympathetic vomiting may be used as a survival tactic.
Some experts think that vomiting urges can be controlled by consuming certain foods and beverages or attempting to relax the body through deep breathing or other meditation tactics. If you feel yourself becoming nauseous, try slowly drinking a clear carbonated beverage like seltzer, or stepping outside to get some air. Try to distract your mind with an activity, and do not eat any very hot or cold foods for a while.
If you fear you may be subject to sympathetic vomiting, get out of the room or area if someone is vomiting or appears to be getting sick. Getting away from the sight, smell and sounds may prevent you from suffering any ill effects. You may want to try taking an anti-nausea medication, such as those sold to prevent seasickness. Again, trying to distract your mind may be key to preventing nausea and vomiting. Do not try to exercise right away however, as some types of exertion can induce nausea.