Vomiting

Vomiting (known medically as emesis and informally as throwing up and a number of other terms) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting may result from many causes, ranging from gastritis or poisoning to brain tumors, or elevated intracranial pressure. The feeling that one is about to vomit is called nausea, which usually precedes, but does not always lead to, vomiting. Antiemetics are sometimes necessary to suppress nausea and vomiting, and, in severe cases where dehydration develops, intravenous fluid may need to be administered to replace fluid volume.

Vomiting is different from regurgitation, although the two terms are often used interchangeably. Regurgitation is the return of undigested food back up the esophagus to the mouth, without the force and displeasure associated with vomiting. The causes of vomiting and regurgitation are generally different.

Complications

Aspiration of vomit

Vomiting can be dangerous if the gastric content gets into the respiratory tract. Under normal circumstances the gag reflex and coughing will prevent this from occurring, however these protective reflexes are compromised in persons under the influences of certain substances such as alcohol or anesthesia. The individual may choke and asphyxiate or suffer an aspiration pneumonia.

Dehydration and electrolyte imbalance

Prolonged and excessive vomiting will deplete the body of water (dehydration) and may alter the electrolyte status. Gastric vomiting leads to the loss of acid (protons) and chlorine directly. Combined with the resulting alkaline tide, this leads to hypochloremic metabolic alkalosis (low chloride levels together with high HCO3 and CO2 and increased blood pH) and often hypokalemia (potassium depletion). The hypokalemia is an indirect result of the kidney compensating for the loss of acid. With the loss of intake of food the individual may eventually become cachectic. A less frequent occurrence results from a vomiting of intestinal contents, including bile acids and HCO3- which can lead to metabolic acidosis.

Mallory-Weiss tear

Repeated or profuse vomiting may cause erosions to the esophagus or small tears in the esophageal mucosa (Mallory-Weiss tear). This may become apparent if fresh red blood is mixed with vomit after several episodes.

Dentistry

Recurrent vomiting, such as observed in bulimia nervosa, may lead to destruction of the tooth enamel due to the acidity of the vomit. Digestive enzymes can also have a negative effect on oral health, by degrading the tissue of the gums.

Differential diagnosis

Vomiting may be due to a large number of causes, and protracted vomiting has a long differential diagnosis.

Digestive tract

Causes in the digestive tract

• Gastritis (inflammation of the gastric wall, usually by viruses)
• Gastroenteritis
• Pyloric stenosis (in babies, this typically causes a very forceful "projectile vomiting" and is an indication for urgent surgery)
• Bowel obstruction
• Overeating
• Acute abdomen and/or peritonitis
• Ileus
• Food allergies (often in conjunction with hives or swelling)
• Cholecystitis, pancreatitis, appendicitis, hepatitis
• Food poisoning
• In children, it can be caused by an allergic reaction to cow's milk proteins (Milk allergy or lactose intolerance)

Sensory system and brain

• Causes in the sensory system
• Movement: motion sickness (which is caused by overstimulation of the labyrinthine canals of the ear)
• Ménière's disease

Causes in the brain

• Concussion
• Cerebral hemorrhage
• Migraine
• Brain tumors, which can cause the chemoreceptors to malfunction
• Benign intracranial hypertension and hydrocephalus

Metabolic disturbances (these may irritate both the stomach and the parts of the brain that coordinate vomiting)

• Hypercalcemia (high calcium levels)
• Uremia (urea accumulation, usually due to renal failure)
• Adrenal insufficiency
• Hypoglycemia
• Hyperglycemia

Pregnancy

• Hyperemesis, Morning sickness

Drug reaction (vomiting may occur as an acute somatic response to)

• alcohol (being sick while being drunk or being sick the next morning, suffering from the after-effects, i.e., the hangover).
• opioids
• selective serotonin reuptake inhibitors
• many chemotherapy drugs
• some entheogens (such as peyote or ayahuasca)

Illness

• Norwalk virus
• Swine Flu

Emetics

An emetic, such as syrup of ipecac, is a substance that induces vomiting when administered orally or by injection. An emetic is used medically where a substance has been ingested and must be expelled from the body immediately (for this reason, many toxic and easily digestible products such as rat poison contain an emetic). Inducing vomiting can remove the substance before it is absorbed into the body. Ipecac abuse can cause detrimental health effects.

Salt water and mustard water have been used since ancient times as emetics. Care must be taken with salt, as excessive intake can potentially be harmful.

Copper sulfate was also used in the past as an emetic. It is now considered too toxic for this use.

Social cues

It is quite common that, when one person vomits, others nearby will become nauseated, particularly when smelling the vomit of others, often to the point of vomiting themselves. It is believed that this is an evolved trait among primates. Many primates in the wild will tend to browse for food in small groups. Should one member of the party react adversely to some ingested food, it may be advantageous (in a survival sense) for other members of the party also to vomit. This tendency in human populations has been observed at drinking parties, where excessive consumption of alcoholic beverages may result in a number of party members vomiting nearly simultaneously, this being triggered by the initial vomiting of a single member of the party. This phenomenon has been touched on in popular culture: Notorious instances appear in the films Monty Python's The Meaning of Life (1983) and Stand By Me(1986), while, in the computer game Theme Hospital, it is referred to as a 'vomit wave' and can spread through the hospital quickly.

Intense vomiting in ayahuasca ceremonies is a common phenomenon. However, people who experience "la purga" after drinking ayahuasca, in general, regard the practice as both a physical and spiritual cleanse and often come to welcome it. It has been suggested that the consistent emetic effects of ayahuasca — in addition to its many other therapeutic properties — was of medicinal benefit to indigenous peoples of the Amazon, in helping to clear parasites from the gastrointestinal system.

There have also been documented cases of a single ill and vomiting individual inadvertently causing others to vomit, when they are especially fearful of also becoming ill, through a form of mass hysteria.

Context

Most people try to contain their vomit by vomiting into a sink, toilet, or trash can, as both the act and the vomit itself are widely considered embarrassing; vomit is also difficult to clean. On airplanes and boats, special bags are supplied for sick passengers to vomit into. A special disposable bag containing absorbent material that solidifies the vomit quickly is available, also, making it convenient and safe to keep (leakproof, puncture-resistant, odorless) until there is an opportunity to dispose of it conveniently.

People who vomit chronically (e.g., as part of an eating disorder such as bulimia nervosa) may devise various ways to hide this disorder.

Sound

An online study of people's responses to "horrible sounds" found vomiting "the most disgusting". Professor Cox of the University of Salford's Acoustic Research Centre said that "We are pre-programmed to be repulsed by horrible things such as vomiting, as it is fundamental to staying alive to avoid nasty stuff." It is thought that disgust is triggered by the sound of vomiting to protect food from those possibly diseased nearby.

Miscellanea

Self-induced

• Eating disorders (anorexia nervosa or bulimia nervosa)
• To eliminate an ingested poison (some poisons should not be vomited as they may be more toxic when inhaled or aspirated; it is better to ask for help before inducing vomiting)
• Some people who are engaged in binge drinking will induce vomiting in order to make room in their stomachs for further alcohol consumption.
• People suffering from nausea may induce vomiting in hopes of feeling better.

Additional causes

• After surgery (postoperative nausea and vomiting)
• Disagreeable sights, smells or thoughts (such as decayed matter, others' vomit, thinking of vomiting), etc.
• Extreme pain, such as intense headache or myocardial infarction (heart attack)
• Violent emotions
• Cyclic vomiting syndrome (a poorly-understood condition with attacks of vomiting)
• High doses of ionizing radiation will sometimes trigger a vomit reflex in the victim
• Violent fits of coughing, hiccups, or asthma
• Nervousness
• Anxiety
• Overexertion (doing too much strenuous exercise can lead to vomiting shortly afterwards).
• Rumination syndrome, an underdiagnosed and poorly understood disorder that causes sufferers to regurgitate food shortly after ingestion.

Treatment

An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side-effects of medications such as opioids and chemotherapy.

Antiemetics act by inhibiting the receptor sites associated with emesis. Hence, anticholinergics, antihistamines, dopamine antagonists, serotonin antagonists, and cannabinoids are used as anti-emetics.