1 Definition and terminology

1.1 Basic definition

Vomiting is the forceful expulsion of stomach contents through the mouth. It is a symptom, not a disease, and usually reflects activation of a protective reflex in response to irritation, infection, toxins, motion, or disturbances involving the digestive system or nervous system. Episodes may be brief and isolated or repeated and severe.

Vomiting is often discussed alongside several related phenomena that can look similar but differ in mechanism and clinical meaning.

1.2.1 Nausea

Nausea is the unpleasant sensation that often precedes vomiting. It may occur without actual emesis and is commonly described as a feeling of queasiness or an urge to vomit.

1.2.2 Regurgitation

Regurgitation is the effortless return of material from the stomach or esophagus into the mouth. Unlike vomiting, it usually does not involve forceful abdominal contractions or preceding nausea.

1.2.3 Retching

Retching refers to the rhythmic, unproductive contractions associated with the vomiting reflex when no stomach contents are expelled. It is sometimes called dry heaving.

1.3 Types of vomiting

Vomiting may be classified by pattern, duration, or cause. Acute vomiting develops suddenly and usually lasts a short time. Persistent or chronic vomiting continues over longer periods and more often suggests an underlying disorder. Projectile vomiting is a forceful form in which material is expelled with considerable distance, and it may indicate obstruction or increased pressure in certain settings.

2 Causes and triggers

Vomiting can arise from disorders affecting the gastrointestinal tract, the nervous system, the whole body, or from external triggers such as medications and motion. In many cases, more than one factor is involved.

2.1 Gastrointestinal causes

Disorders of the stomach and intestines are among the most common reasons for vomiting. These conditions often irritate the digestive tract directly or interfere with normal movement of its contents.

2.1.1 Infections

Viral, bacterial, and parasitic infections may cause vomiting through inflammation and release of toxins. Gastroenteritis is a frequent example and is often accompanied by diarrhea, abdominal cramps, or fever.

2.1.2 Obstruction

A blockage in the stomach or intestines can prevent normal passage of food and fluid, leading to vomiting. Obstruction may result from twisting, narrowing, tumors, hernias, or severe constipation.

2.1.3 Inflammation

Inflammatory conditions such as gastritis, appendicitis, pancreatitis, or gallbladder inflammation may provoke vomiting. The symptom may arise from local irritation, pain, or reflex pathways that respond to abdominal inflammation.

2.2 Neurological causes

The nervous system helps regulate the vomiting reflex, so disorders affecting the brain or its coverings can produce vomiting even without direct digestive disease.

2.2.1 Migraine

Migraine attacks commonly include nausea and vomiting. These symptoms are part of the broader neurological episode and may occur with headache, sensitivity to light, or sound.

2.2.2 Increased intracranial pressure

Raised pressure within the skull can stimulate vomiting centers in the brain. This may occur with head injury, tumors, bleeding, hydrocephalus, or severe brain swelling.

2.3 Systemic and metabolic causes

Vomiting may accompany conditions that alter the body’s internal chemistry or affect multiple organs. In such cases, vomiting is often only one feature of a broader illness.

2.3.1 Pregnancy

Vomiting is common in early pregnancy, especially during the first trimester. It is often linked to hormonal changes and heightened sensitivity to smells and other stimuli.

Diabetes can lead to vomiting during severe blood sugar disturbances, including diabetic ketoacidosis. Long-standing diabetes may also impair stomach emptying, a condition known as gastroparesis.

2.3.3 Kidney and liver disorders

Advanced kidney disease can cause nausea and vomiting through toxin buildup, while liver disorders may do so through metabolic imbalance or complications such as jaundice and fluid accumulation.

Many substances can irritate the stomach directly or act on the brain’s vomiting centers. Drug reactions and poisonings are important considerations when vomiting begins after exposure to a new agent.

2.4.1 Drug side effects

Numerous medications may cause vomiting as an adverse effect. Common examples include certain antibiotics, opioids, chemotherapy agents, and drugs that irritate the stomach lining.

2.4.2 Poisoning

Ingested toxins, alcohol, or contaminated substances may trigger vomiting as the body attempts to expel harmful material. The pattern of symptoms often depends on the agent involved.

2.5 Motion and sensory triggers

The vomiting reflex can be activated by sensory mismatch or intense environmental input. These triggers are especially common in otherwise healthy people.

2.5.1 Motion sickness

Motion sickness develops when the brain receives conflicting signals from the inner ear, eyes, and body position. It is common during travel by car, boat, or aircraft.

2.5.2 Strong odors and visual stimuli

Powerful smells, unpleasant sights, or visually intense environments can provoke nausea and vomiting in susceptible individuals. Such triggers are often more noticeable during pregnancy, migraine, or motion sensitivity.

3 Pathophysiology

Vomiting results from coordinated activity across the brain, autonomic nervous system, diaphragm, abdominal muscles, esophagus, and stomach. The reflex is highly organized and involves both sensory detection and motor response.

3.1 Vomiting reflex

The vomiting reflex is a protective mechanism designed to expel potentially harmful material. It is controlled by brain circuits that integrate signals from the gut, inner ear, bloodstream, and higher brain regions.

3.1.1 Brainstem control centers

Key control centers are located in the brainstem, especially in the medulla. These centers coordinate the sequence of events that produce nausea, retching, and expulsion.

3.1.2 Sensory input pathways

Input may come from the gastrointestinal tract through vagal and sympathetic nerves, from the vestibular system during motion, from blood-borne toxins, or from cerebral structures in response to pain or pressure changes.

3.2 Physiological changes during vomiting

Vomiting involves a series of rapid muscular and sphincter changes that move stomach contents upward and out of the body.

3.2.1 Abdominal muscle contraction

The diaphragm and abdominal muscles contract forcefully, increasing pressure inside the abdomen and pushing gastric contents upward.

3.2.2 Esophageal and gastric relaxation

The lower esophageal sphincter and the upper stomach relax to permit the upward passage of material. At the same time, closure of the airway helps limit aspiration.

4 Clinical presentation

The clinical appearance of vomiting depends on the cause, the volume lost, and the duration of symptoms. Associated signs often provide important diagnostic clues.

4.1 Associated symptoms

Vomiting is frequently accompanied by other symptoms that reflect the underlying disorder.

4.1.1 Nausea

Nausea commonly precedes vomiting and may persist afterward. It is often one of the earliest warning sensations reported by patients.

4.1.2 Abdominal pain

Abdominal discomfort may indicate inflammation, infection, obstruction, or another gastrointestinal process. The location and intensity of pain can help narrow the cause.

4.1.3 Fever

Fever suggests infection or inflammation, though it is not present in every case. Its presence may point toward gastroenteritis, appendicitis, or other systemic illness.

4.2 Characteristics of vomit

The appearance of vomited material can provide useful diagnostic information, especially when combined with symptoms and examination findings.

4.2.1 Color

Vomit may appear clear, yellow, green, brown, or bloody. Color changes can reflect stomach contents, bile, digested blood, or fecal material in severe obstruction.

4.2.2 Contents

Vomited material may contain recently ingested food, mucus, stomach acid, or partially digested material. Undigested food may suggest delayed gastric emptying or regurgitation-like episodes.

4.2.3 Presence of blood or bile

Blood in vomit may indicate irritation, tears, or bleeding in the upper digestive tract. Bile often gives a green or yellow color and may suggest duodenal reflux or intestinal obstruction beyond the stomach.

4.3 Red flag features

Certain findings indicate a greater likelihood of serious illness and usually warrant prompt medical evaluation.

4.3.1 Severe dehydration

Signs include dry mouth, reduced urination, dizziness, sunken eyes, and weakness. In severe cases, dehydration may lead to shock or organ dysfunction.

4.3.2 Altered mental status

Confusion, drowsiness, lethargy, or decreased responsiveness may indicate intoxication, metabolic disturbance, infection, or raised intracranial pressure.

4.3.3 Persistent or projectile vomiting

Repeated vomiting that does not resolve, or forceful projectile episodes, may signal obstruction, neurological disease, or another significant underlying problem.

5 Diagnosis

Evaluation aims to identify the cause, assess severity, and detect complications such as dehydration or electrolyte disturbance. The approach depends on the patient’s age, associated symptoms, and clinical stability.

5.1 Medical history

History taking includes onset, duration, frequency, triggers, associated pain, fever, diarrhea, headaches, medication use, pregnancy possibility, travel, and exposure to toxins or sick contacts. The character of the vomit and the presence of weight loss or neurological symptoms are also important.

5.2 Physical examination

Examination focuses on hydration status, abdominal tenderness, bowel sounds, fever, and signs of neurological impairment. In some cases, findings such as abdominal distension, guarding, or altered consciousness guide further testing.

5.3 Laboratory tests

Laboratory studies are used to identify infection, metabolic abnormalities, organ dysfunction, and complications from fluid loss.

5.3.1 Blood tests

Blood tests may include electrolytes, kidney function, liver function, glucose, blood counts, and markers of inflammation. Additional tests are ordered when specific disorders are suspected.

5.3.2 Urine tests

Urinalysis can help evaluate dehydration, infection, ketones, and pregnancy. It may also assist in assessing metabolic causes such as diabetic ketoacidosis.

5.4 Imaging studies

Imaging is considered when structural disease, obstruction, or neurological causes are suspected.

5.4.1 Abdominal imaging

X-rays, ultrasound, or computed tomography may identify bowel obstruction, gallbladder disease, appendicitis, or other abdominal pathology.

5.4.2 Brain imaging

Brain imaging is used when symptoms suggest increased intracranial pressure, head injury, focal neurological deficits, or other intracranial disorders.

5.5 Differential diagnosis

Vomiting must be distinguished from regurgitation, coughing, gagging, and other causes of expelling material from the mouth. Clinicians also consider abdominal emergencies, poisoning, pregnancy-related symptoms, vestibular disorders, migraine, and systemic metabolic illness.

6 Treatment and management

Management depends on cause and severity. Mild, self-limited vomiting may only require supportive care, while persistent or dangerous cases need targeted treatment and monitoring.

6.1 Supportive care

Supportive measures aim to restore fluids, reduce irritation, and prevent complications while the underlying cause is addressed.

6.1.1 Fluid replacement

Oral rehydration is often used when vomiting is mild and the person can drink. Intravenous fluids may be necessary when dehydration is significant or oral intake is not possible.

6.1.2 Dietary modification

Temporary avoidance of heavy, fatty, or irritating foods may help. Small, bland meals are often better tolerated once vomiting subsides.

6.2 Antiemetic medications

Antiemetics reduce nausea and vomiting by acting on specific neurotransmitter pathways in the brain and gut. Choice of medication depends on age, cause, and potential side effects.

6.2.1 Serotonin antagonists

These medicines are widely used for nausea associated with gastroenteritis, postoperative recovery, and chemotherapy. They block serotonin-mediated signaling involved in the vomiting reflex.

6.2.2 Dopamine antagonists

Dopamine-blocking drugs can be effective for certain types of nausea and vomiting. They are used selectively because they may cause movement-related or sedating side effects.

6.2.3 Antihistamines

Antihistamines are especially helpful for motion sickness and some vestibular disorders. They may also produce drowsiness, which can be useful or limiting depending on the situation.

6.3 Cause-specific treatment

Definitive care focuses on the illness or trigger responsible for vomiting. This may eliminate the symptom and prevent recurrence.

6.3.1 Infection management

Infections may require hydration, symptom control, and, in selected cases, antimicrobial treatment. Most viral causes improve with supportive care alone.

6.3.2 Relief of obstruction

Mechanical obstruction may require decompression, endoscopic intervention, or surgery. The specific approach depends on the location and cause of the blockage.

6.3.3 Management of metabolic disorders

Treatment of conditions such as diabetic ketoacidosis, kidney failure, or electrolyte imbalance is essential when these disorders underlie vomiting. Correcting the systemic problem usually improves the symptom.

6.4 Special situations

Some settings require tailored management because the cause, risks, and treatment options differ from routine care.

6.4.1 Vomiting in pregnancy

Vomiting in pregnancy is commonly treated with dietary changes, hydration, and selected medications when needed. More severe forms require assessment for weight loss, dehydration, and nutritional compromise.

6.4.2 Vomiting in children

Children may become dehydrated quickly, so fluid balance is monitored closely. Careful attention is given to signs of lethargy, inability to drink, and high fever.

6.4.3 Vomiting after surgery

Postoperative vomiting may follow anesthesia, pain, or swallowed blood. Prevention and treatment often include antiemetics, fluid management, and attention to the type of surgery performed.

7 Complications

Repeated or severe vomiting can produce important complications, especially when fluid losses are large or prolonged.

7.1 Dehydration

Loss of fluid and reduced intake can rapidly lead to dehydration. This is particularly significant in infants, older adults, and people with ongoing vomiting from infection or obstruction.

7.2 Electrolyte imbalance

Vomiting may lower potassium, chloride, and other electrolytes, leading to weakness, cramps, or abnormal heart rhythms. Acid-base disturbances can also develop.

7.3 Aspiration

If vomited material enters the airway or lungs, aspiration can occur. This may cause choking, pneumonia, or respiratory distress, especially in people with reduced alertness.

7.4 Esophageal injury

Forceful vomiting increases pressure in the upper digestive tract and may injure the esophagus or surrounding tissues.

7.4.1 Mallory-Weiss tear

A Mallory-Weiss tear is a mucosal laceration near the junction of the esophagus and stomach caused by repeated retching or vomiting. It may produce upper gastrointestinal bleeding.

7.4.2 Rare severe complications

Very severe vomiting can, in rare cases, contribute to esophageal rupture, aspiration-related injury, or significant bleeding. These events are medical emergencies.

8 Prevention

Prevention focuses on reducing exposure to triggers and managing conditions known to provoke vomiting.

8.1 Avoiding triggers

Identifying and avoiding personal triggers, such as certain foods, odors, alcohol, or specific movements, may reduce episodes. People with recurrent vomiting often benefit from recognizing early warning signs.

8.2 Medication precautions

Taking medications exactly as directed, with food when appropriate, may reduce stomach upset. Reviewing new prescriptions for nausea as a possible side effect can help prevent avoidable symptoms.

8.3 Motion sickness prevention

Measures such as sitting in a stable position, looking toward the horizon, improving ventilation, and using preventive medication before travel can lessen motion-induced vomiting.

9 Prognosis

The outlook depends largely on the duration of vomiting and its underlying cause. Many episodes resolve without lasting effects, while others reflect serious disease.

9.1 Self-limited vomiting

Vomiting caused by minor infection, motion sickness, or a short-lived irritant often improves quickly with rest and hydration. Recovery is usually complete.

9.2 Prognosis by underlying cause

When vomiting results from obstruction, neurological disease, severe metabolic disturbance, or poisoning, prognosis depends on the timeliness and effectiveness of treatment. Early recognition generally improves outcomes.

10 History and epidemiology

Vomiting has been recognized since early medical history as both a symptom and a diagnostic clue. Its study has contributed to understanding of digestion, brainstem reflexes, infection, poisoning, and pregnancy-related illness.

10.1 Historical understanding

Traditional medical systems described vomiting in relation to imbalance, food intolerance, or bodily cleansing. Modern medicine later identified the coordinated reflex pathways that produce emesis and clarified the role of infection, toxins, and neurological signaling.

10.2 Frequency and burden

Vomiting is common across all age groups and is among the most frequent reasons for short-term illness at home, in clinics, and in emergency care. Although many episodes are harmless and self-limited, the symptom can create substantial burden through dehydration, missed activities, caregiver concern, and the need to rule out serious underlying disease.

</INTERNAL_LINK_CANDIDATES> Nausea (the unpleasant sensation that often precedes vomiting) Regurgitation (the effortless return of material without forceful vomiting) Retching (unproductive contractions associated with the vomiting reflex) Gastroenteritis (an infectious inflammation of the stomach and intestines) Intestinal obstruction (a blockage that prevents normal passage of intestinal contents) Migraine (a neurological disorder commonly associated with nausea and vomiting) Increased intracranial pressure (raised pressure within the skull that can trigger vomiting) Diabetic ketoacidosis (a severe diabetes complication that may cause vomiting) Gastroparesis (delayed stomach emptying that can lead to vomiting) Motion sickness (nausea and vomiting caused by sensory mismatch during movement) Antiemetic (a medication used to prevent or relieve vomiting) Serotonin antagonist (an antiemetic class that blocks serotonin signaling) Dopamine antagonist (an antiemetic class that blocks dopamine signaling) Antihistamine (a drug class used to prevent motion-related vomiting) Oral rehydration (fluid replacement by mouth to treat dehydration) Electrolyte imbalance (abnormal levels of body salts caused by vomiting) Aspiration (entry of vomit into the airway or lungs) Mallory-Weiss tear (a tear near the esophagus-stomach junction caused by retching) Pregnancy (a common physiological cause of vomiting in early gestation) Dehydration (loss of body fluid caused by vomiting)