Vomiting

Vomiting (also called emesis) is the reflex, involuntary, and sudden act by which the body expels stomach contents through the mouth. It is a response to stimuli received by the medulla oblongata, the structure that connects the brain to the rest of the body by transmitting nerve signals that coordinate essential automatic functions such as breathing, heart rate, sweating, and salivation.

The vomiting center, the term used to describe the neuronal nuclei in the medulla oblongata that coordinate the reflex causing emesis, triggers the return of gastric contents in four stages:

1. Nausea: stomach discomfort that causes the urge to vomit.
2. Inhalation: the glottis closes to protect the airway and prevent stomach contents from entering the lungs.
3. Retching: contractions of the abdominal wall muscles strong enough to generate the pressure needed to expel gastric contents.
4. Expulsion: the upper esophageal sphincter relaxes, allowing gastric contents to rise into the mouth and exit the body.

Vomiting occurs as a consequence of stimuli from different origins. In most cases, the brain receives these signals from the central nervous system, the vestibular system, or the gastrointestinal tract. Therefore, emesis may be caused by a wide variety of conditions. In most cases, vomiting resolves spontaneously within a few days, as occurs with food poisoning or viral infections, although it may also be a symptom of serious conditions requiring specific treatment to avoid compromising the patient’s health.

There are different types of vomit depending on their content and appearance:

• Food vomit: contains partially undigested food remains.
• Bilious vomit: yellow or green in color. It contains bile, the fluid that breaks down fats in the small intestine. It is common in recurrent vomiting episodes or prolonged fasting.
• Hematemesis: contains blood, usually originating from an ulcer or esophageal varices. It may be bright red when bleeding is active or dark brown if the blood has been digested by stomach acid.
• Coffee-ground vomit: very dark, almost black, with a powdery appearance similar to coffee grounds due to the mixture of coagulated blood and gastric juices. It is a sign of gastrointestinal bleeding.
• Mucoid vomit: white and foamy, consisting of mucus mixed with gastric secretions.
• Feculent vomit: may be brown, dark yellow, or green. It contains fecal material and is therefore a sign of intestinal obstruction.

Symptoms

The common symptoms associated with vomiting are:

• Nausea.
• Retching: usually precedes vomiting as unsuccessful attempts to expel gastric contents. It then accompanies vomiting and may recur after the stomach has been completely emptied.
• Pallor.
• Cold sweats.
• Increased salivation.
• Abdominal pain.
• Dizziness.
• Fatigue.
• Headache.
• Loss of appetite.

It is important to monitor for warning signs suggestive of poisoning or a serious condition. Emergency medical attention should be sought if any of the following symptoms occur:

• Dark-colored vomit or vomit containing blood.
• Vomiting lasting more than 2 days.
• Inability to retain fluids for more than 12 consecutive hours.
• Anuria (absence of urine output) for at least 8 hours.
• Severe abdominal pain.
• More than 3 vomiting episodes in one day.
• Abdominal distension.
• Neck stiffness.
• Confusion.
• Reduced alertness.
• A history of head trauma, even if apparently minor, before the onset of vomiting.
• Chest pain.
• Prolonged vomiting carries a risk of dehydration, which requires immediate medical evaluation. The main warning signs are:
• Increased thirst.
• Dry mouth.
• Crying without tears.
• Sunken eyes.
• Dark-colored urine.
• Infrequent urination.
• Changes in skin characteristics: when pinched, the skin does not immediately return to its normal position, as it normally would.
• In babies and children:
• Fever above 38 °C.
• Lethargy.
• Irritability.
• Difficulty waking up.
• Infants vomiting 2 or more feedings.
• Babies vomiting for more than 12 hours.
• Children vomiting for more than 24 hours.

Causes

Vomiting may be caused by different circumstances. The most common include:

• Food allergies.
• Food poisoning.
• Accidental ingestion of toxic substances.
• Use of illicit substances.
• Gastric or intestinal infection, most commonly viral gastroenteritis.
• Gastroesophageal reflux disease: abdominal pressure increases or the esophageal sphincters do not close properly, allowing stomach acids to rise into the esophagus and cause heartburn and swallowing difficulties.
• Gastric or intestinal ulcers.
• Intestinal obstruction: partial or complete blockage of the intestine that prevents the passage of food, fluids, and gas.
• Appendicitis: inflammation of the appendix, a small pouch attached to the large intestine that contributes to the production of immunoglobulin A, which helps regulate the quality and density of the intestinal microbiota.
• Pancreatitis: inflammation of the pancreas, the gland responsible for regulating blood sugar and aiding digestion.
• Gastroparesis: dysfunction of the intestinal wall muscles that impairs digestion.
• Stomach cancer.
• Cyclic vomiting syndrome: recurrent episodes of severe vomiting without an apparent cause.
• Hormonal changes during pregnancy (increased estrogen and hCG levels).
• Hyperthyroidism: excessive production of thyroid hormones may overstimulate intestinal nerves and accelerate metabolism.
• Hypothyroidism: reduced thyroid hormone levels cause constipation and decreased intestinal motility, which may lead to vomiting.
• Motion sickness.
• Vertigo: a sensation of movement caused by a disorder affecting the inner ear or the brain.
• Severe pain.
• Migraines: throbbing headache, usually affecting one side, accompanied by increased sensitivity to light and sounds.
• Meningitis: inflammation of the meninges (the fluid and membranes surrounding the brain) due to infection.
• Encephalitis: inflammation of the encephalon, the organ located within the skull and composed of the cerebrum, cerebellum, and brainstem. It is usually caused by infection or autoimmune disorders in which the body attacks its own cells.
• Increased intracranial pressure, which may result from various conditions:
• Brain tumor.
• Hydrocephalus: accumulation of cerebrospinal fluid within the brain ventricles.
• Cerebral hemorrhage.
• Epilepsy: chronic nervous system disorder causing recurrent seizures associated with convulsions and sometimes loss of consciousness.
• Chiari malformation: structural defect at the base of the skull in which the cerebellum extends into the spinal canal and compresses the brainstem.

Risk factors

The risk of vomiting increases in the following situations:

• Traveling in moving vehicles.
• Alcoholism.
• Anaphylaxis: severe systemic allergic reaction to an allergen.
• Crohn’s disease: inflammation of the digestive tract tissues increases susceptibility to vomiting.
• Irritable bowel syndrome: chronic functional disorder causing pain, abdominal distension, and changes in bowel habits.
• Taking medications or undergoing medical treatments whose side effects include vomiting:
• Chemotherapy.
• Anesthetics.
• Opioid analgesics.
• Nonsteroidal anti-inflammatory drugs.
• Narcotics.
• Antibiotics.
• Oral contraceptives.
• Radiotherapy.
• Eating disorders such as anorexia or bulimia; in these cases, vomiting is usually self-induced.
• Eating too quickly, overeating, or fasting.
• Fever.
• Severe coughing.
• Generalized anxiety: hormones released, such as cortisol, alter the digestive system.
• Diabetes: poor blood glucose control may lead to ketoacidosis (acid accumulation) or gastroparesis.

In babies and children, vomiting may be caused by:

• Immaturity of the digestive system, especially of the lower esophageal sphincter, which fails to close properly and promotes reflux.
• Overfeeding.
• Pyloric stenosis: narrowing of the pylorus, the valve connecting the stomach to the duodenum (small intestine).
• Intussusception: one part of the intestine slides into another, causing painful obstruction.

Complications

Vomiting, especially when persistent, may cause serious complications such as:

• Dehydration.
• Esophageal tear.
• Erosive esophagitis: gastric acid causes inflammation of the esophagus.
• Boerhaave syndrome: complete esophageal rupture due to violent vomiting.
• Dental erosion (due to the effects of acid).
• Malnutrition.
• Weight loss.
• Cardiac arrhythmias (due to electrolyte imbalance).
• Pulmonary aspiration: part of the vomit enters the lungs and may lead to:
• Inflammation.
• Pneumonia (infection).
• Asphyxia.
• Death.

What doctor treats vomiting?

Vomiting is usually managed within the specialties of Family and community medicine, Pediatrics, or Emergency department. In some cases, specialists in General Medicine, Gastroenterology, or Neurology may also be involved.