Why Do We Vomit?
- Fysiobasen
- Sep 29
- 3 min read
Vomiting, or emesis in medical terms, is a powerful bodily reaction that everyone experiences at some point. It is a complex process where the body forcefully expels stomach contents through the mouth. Although it feels unpleasant and intense, vomiting is primarily a protective mechanism the body uses to eliminate harmful substances or respond to physiological imbalance¹.
Why Do We Vomit?
Vomiting, or emesis in medical terms, is a powerful bodily reaction that everyone experiences at some point. It is a complex process where the body forcefully expels stomach contents through the mouth. Although it feels unpleasant and intense, vomiting is primarily a protective mechanism the body uses to eliminate harmful substances or respond to physiological imbalance¹.
What Happens in the Body During Vomiting?
Vomiting is controlled by an area in the brainstem known as the vomiting center. This center receives signals from different parts of the body, including the gastrointestinal tract, the inner ear (balance system), and the brain itself². When activated, the vomiting center triggers nerve impulses that:
Close the larynx to prevent stomach contents from entering the lungs.
Relax the esophageal sphincters.
Contract the abdominal muscles to force stomach contents upward.
The entire process happens quickly and involuntarily, often preceded by nausea as a warning sign.
What Can Trigger Vomiting?
Vomiting can be caused by many different stimuli:
Gastrointestinal infections: Viruses, bacteria, or parasites that irritate the stomach or intestines³.
Food poisoning: Toxins in spoiled food can directly activate the vomiting center.
Pregnancy: Many women experience nausea and vomiting, especially during the first trimester.
Motion sickness: Mismatch between visual input and the inner ear’s balance system.
Toxins and medications: Substances like alcohol or chemotherapy drugs can stimulate the vomiting center.
Severe pain or emotional stress: Can directly affect the brain and induce vomiting⁴.
What Is the Purpose of Vomiting?
The primary function of vomiting is protection. By expelling potentially harmful substances before they are absorbed into the bloodstream, the body prevents serious poisoning or infection. In other cases, vomiting is a symptom of underlying conditions that require medical attention.
When Should Vomiting Be a Concern?
While vomiting often resolves on its own, medical attention is needed if:
It persists longer than 24–48 hours.
Signs of dehydration occur (dizziness, dry mouth, dark urine).
There is blood in the vomit or it resembles coffee grounds.
Severe abdominal pain or headache accompanies it.
Vomiting occurs after a head injury⁵.
Such symptoms may indicate more serious conditions, including concussion, intestinal obstruction, or infection.
How to Manage Vomiting
Rest and sip small amounts of fluids frequently to avoid dehydration.
Avoid solid food until nausea subsides; start with bland items like crackers or rice.
Stay away from strong odors and vigorous movement, which may worsen nausea.
Anti-nausea medication can be used under medical supervision, especially for persistent or severe symptoms.
Summary
Vomiting is a natural protective response that helps the body eliminate harmful substances or adapt to imbalances. In most cases, it is harmless and self-limiting. However, persistent or severe symptoms warrant medical evaluation to rule out serious conditions.
Sources:
Horn CC. “Why is the neurobiology of nausea and vomiting so important?” Appetite, 2008.
Andrews PLR, et al. “Neuropharmacology of emesis.” British Journal of Pharmacology, 1990.
Thiel HJ. “Pathogenesis and pathophysiology of viral gastroenteritis.” Infection, 1989.
Wood JD. “Neurophysiology of nausea and vomiting.” Gastroenterology Clinics of North America, 1994.
Bafaqeeh SA, et al. “Posttraumatic vomiting: a clinical and experimental study.” Journal of Laryngology and Otology, 1994.
