Nausea is an unpleasant feeling in the pit of the stomach that one is about to vomit. Vomiting is a reflex where the vomiting centre in the brain tells the intestines to reverse their peristaltic movements in order to force the contents of the stomach out through the mouth.
Nausea and vomiting have many possible causes, and are not always related to disease of the gastro-intestinal tract. Sometimes no cause can be found for vomiting. Vomiting is induced in the brain in a specific location in the hypothalamus, called the vomiting centre.
The vomiting centre can be stimulated by:
- Psychological problems, when it is referred to as psychogenic or functional nausea and vomiting
- Severe pain or shock
- Unpleasant smells or pictures
- Disturbances in the inner ear in conditions such as altitude sickness, Meniere's disease, motion sickness and labyrinthitis. Sometimes middle-ear infection in children can cause vomiting, but then it is caused by an irritated nerve that runs through the middle ear
- Diseases of the internal organs (viscera):
- Gastro-intestinal disease such as gastritis, peptic ulcer, stomach cancer, gut obstruction, appendicitis and mesenteric adenitis
- Disease of the liver or gallbladder such as cholecystitis, hepatitis and cirrhosis
- Disease of the heart such as myocarditis, severe hypertension, heart attack (myocardial infarction) and congestive heart failure
- Disease of the brain such as migraine, stroke (cerebrovascular accident), brain tumors, cerebral hypoxia and epilepsy
- Disease of the urinary tract such as urinary tract infections and renal colic
- Chemicals and toxins
- Infections lead to the production of certain chemicals that can cause fever (pyrogens) and also stimulate the vomiting centre, for example:
- Bacterial and viral infections, such as cholera and salmonella, that can cause either gastro-intestinal or systemic infections
- Parasitic infections, such as malaria
- Certain endocrine problems, such as hyperparathyroidism, hyperthyroidism and diabetes mellitus, produce chemical imbalances that stimulate the vomiting centre
- The waste products that accumulate in the body with renal failure and other electrolyte disturbances can stimulate the vomiting centre in the brain
- Certain drugs and hormones can stimulate the vomiting centre, causing nausea and vomiting: digoxin, morphine, estrogens, iron preparation and aminophylline
- Other conditions, such as morning sickness, haemolytic anaemia, porphyria, alcoholism and radiotherapy
- Self-induced vomiting in psychiatric conditions such as bulimia nervosa
- Congenital malformations of the gastro-intestinal tract such as pyloric stenosis and gastro-oesophageal reflux
Once the vomiting centre in the brain is stimulated, the peristaltic movement of the intestines goes into reverse. The person first experiences a nauseous feeling in the pit of the stomach and produces large quantities of saliva that contain a lot of mucus. The person may also feel weak and sweaty. The glottis closes and breathing stops (this prevents the vomit from entering the lungs). An involuntary contraction of the stomach muscles follows, and the content of the stomach is forced out through the mouth.
Most of the time nausea and vomiting are mild and self-limiting.
More severe cases of vomiting may cause fluid and electrolyte loss. In such cases oral rehydration and treatment is not practical and hospitalisation is required for intravenous therapy.
Psychogenic or functional nausea and vomiting have many causes and can occur in different ways. This kind of vomiting happens either voluntarily or involuntarily. For instance a person can start vomiting involuntarily in a very stressful situation; or if somebody had been brought up with the perception that a certain kind of food is repulsive, then eating that food may cause involuntary vomiting. On the other hand, some people deliberately induce vomiting to gain something like sympathy, or to get out of a difficult situation.
People who receive cancer treatment often feel nauseous afterwards. Radiation therapy causes certain by-products that stimulate the vomiting centre in the brain, while the drugs used for chemotherapy directly stimulate the vomiting centre.
Children are more prone to vomiting for trivial reasons such as a mild fever.
Most infants tend to bring up small amounts of milk when winded, and this should not cause any worry. Changing the feeding conditions often helps, for example reducing the feed, or changing the nipple size.
Some women experience nausea and vomiting during the first trimester of pregnancy, while others have no problems at all. The hormones produced by the placenta cause this nausea. It usually occurs early in the morning, but may occur at any time of the day. The nausea and vomiting of first trimester of pregnancy is usually mild and medication should be avoided.
'Morning sickness', as it is called, mostly occurs during the first six to eleven weeks of pregnancy. Only a few women are nauseous after twelve weeks into the pregnancy.
Hyperemesis gravidarum is more rare and occurs in about five of every 1 000 pregnancies. It is persistent vomiting in pregnant women to the extent that they become starved (do not gain weight) and dehydrated. This may even cause severe liver damage. Although many pregnant women feel as if they are vomiting all their food, this condition exists only if they fail to gain weight or if they have become dehydrated. Initially Hyperemesis gravidarum is treated with intravenous water, glucose and electrolytes, and later with bland oral feedings in small quantities. Psychological factors and personality traits play an important role in this condition. High levels of human chorionogonadotropin (a hormone) also cause this condition, as well as multiple pregnancies.
Many people experience nausea and/or vomiting when travelling by road, train, sea or air. This is called motion or travel sickness. Children in particular are prone to travel sickness.
Bulimia nervosa affects primarily females of the upper and middle class.
When to see a doctor
- If vomiting persists for longer than 24 hours
- If a child under the age of 9 months stays ill for longer than half a day. A child at this age may lose a dangerous amount of body fluid in such a short time
- If signs of dehydration develop, such as a dry tongue, severe thirst, fast breathing, sunken eyes, dry skin or if less urine than normal is passed
- If the person has had diarrhoea or vomiting very recently and he/she becomes confused
- If vomiting and/or nausea accompanies any of these symptoms:
- Fever, temporary hearing loss, vomiting and pulling of the ear in young children, especially after a cold – there may be a middle-ear infection
- Neurological signs such as numbness, loss of speech, which may indicate a stroke (cerebrovascular accident)
- Blood or a coffee ground-like substance in the vomit, which may indicate a bleeding peptic ulcer
- Jaundice (eyes and skin turn yellow, and may be accompanied by dark urine, light-coloured stools and general itching), which may indicate hepatitis
- Mild fever, headache, vomiting and muscular pain, and sudden chills and intense shivering some time after visiting a malaria area
- Disturbed vision, feeling of numbness, pins and needles and headache, which may indicate migraine
- Cramping pain, distention of the abdomen and constipation, which may indicate bowel obstruction
- Generalised abdominal pain that later shifts to lower right side, and loss of appetite, which may indicate appendicitis
- Pain in the right upper side of the abdomen that radiates to between the shoulder blades or the right shoulder, a possible indication of cholecystitis
- Sudden onset of severe abdominal pain after a big meal, especially if the person has gallbladder disease or drinks heavily, which may indicate pancreatitis
- Repeated projectile vomiting in an infant, or increasing amounts of vomit, which may indicate pyloric stenosis or gastro-oesophageal reflux
- Fever in an infant, which may indicate an infection
- Black, tarry stools (also called melena), which is blood that has been altered in the digestive tract. It may indicate an ulcer or cancer of the gastro-intestinal tract
- Severe headaches, sleepiness, lethargy or stiff neck. It may indicate bleeding in the meningis or, if fever is also present, it may indicate meningitis
- Recent bump on the head and vomiting afterwards
- Pregnancy and an inability to keep food down
- Chest pain that radiates into the jaw or left arm, sweating, shortness of breath, which may indicate angina or a heart attack (myocardial infarct)
- Chest pain, fever, shortness of breath and palpitations, which may indicate myocarditis or pericarditis
- A headache that is worse after lying down, when coughing and sneezing, and vomiting that occurs early in the morning. It may indicate raised intracranial pressure associated, for instance, with brain cancer
- If you think the medication you are taking is making you ill
When you decide to consult a health professional about nausea and/or vomiting, make sure you take note of the following:
- The amount vomited – vomiting large quantities of food and other gastric secretions later in the day may indicate gastric outlet obstruction
- The color of the vomit:
- bright red blood suggests bleeding from the oesophagus
- dark red vomit with liver-like clots suggests profuse bleeding in the stomach, such as of a peptic ulcer
- coffee ground-like vomit suggests less acute bleeding in the stomach, because the gastric acid has had time to change the composition of the blood
- yellow vomit suggests bile and is an indication that the pyloric valve is open en bile is flowing into the stomach (this is more common in older people)
- If the vomit is sour and contains recent food
- The relationship to eating
- The time of day that it occurs – vomiting in the morning may indicate pregnancy, alcoholism or anxiety
- If vomiting is preceded by nausea or if it occurs suddenly – the absence of nausea may indicate raised pressure in the brain
- If vomiting relieves abdominal pain (it may be due to a peptic ulcer)
- If there is persistent vomiting without weight loss, which may indicate of a psychological problem
- The problem with vomiting alone is that body water is lost, as well as electrolytes such as sodium and chloride. If untreated, this may lead to dehydration. Dehydration is marked by thirst, dry mouth, fast breathing, sunken eyes and a reduction in the amount of urine passed.
- If a person vomits for a long time, the oesophagus may tear and this may lead to massive bleeding and the vomiting of big amounts of bright red blood, a condition which is called Mallory Weiss syndrome.
- In prolonged or repeated vomiting, they hydrochloric acid in the gastric juices may damage the enamel of the teeth.
It is most important to try and keep up the body’s supply of water by taking in as much clear fluid as possible. Rehydration liquids are an excellent choice, as they also contain electrolytes, but remember to take a small quantity at a time.
If dehydration does occur, or if the person is not able to keep any fluids down, he/she will have to be hospitalised and treated with intravenous water, electrolytes and glucose.
If an unconscious person vomits, he or she can inhale the vomit, which can lead to aspiration pneumonitis, or even worse choke to death on that vomit. For that reason you should always turn an unconscious on his or her side and make sure that the airway remains open.
The next stage is to try and treat or eliminate the cause of the vomiting. It will be necessary to consult a health professional. For example, if it is caused by non-cytotoxic drugs, the health professional may reduce the dose, change the route via which the drug is taken, or change the kind of medication.
If the health professional suspects a peptic ulcer, the person will be referred for a gastroscopy to confirm the diagnosis.
There are numerous preparations available over the counter for the treatment of nausea and vomiting.
For the treatment or prevention of travel or motion sickness, try the following:
- Promethazine: Brunazine, Daralix
- A mixture of sugar and phosphoric acid: Emetrol, Emex
- Cyclizine: Ryccard, Valoid
- Cinnarizine: Stugeron
For rehydration, try one of these solutions:
- Hydrol powder
Reviewed by Prof Don du Toit (M.B.Ch.B) (D.Phil.) (Ph.D) (FCS) (FRCS).