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There are many possible causes for nausea and vomiting, which is not always related to conditions of the gastro-intestinal (GIT) tract.
Sometimes no cause can be found for vomiting, an action which is induced in the brain in a specific location called the vomiting centre. The body’s vomiting centre can be stimulated by physical or psychological causes.
Physical
• Most common causes relate to something you have eaten or have eaten too much of. If you have nausea and vomiting, take note of what you have eaten in the last few hours, especially chicken or sea food. If you are taking any prescription or over the counter drugs be sure to mention this to your doctor.
• Diseases of the oral cavity, tonsillitis, post nasal drip and sinusitis.
• Chemicals and toxins
• Infections lead to the production of certain chemicals that can cause fever (pyrogens) and also stimulate the vomiting centre. These include:
o Bacterial and viral infections such as salmonella that can cause either gastro-intestinal or systemic infections
o Rota virus, especially in children
o Parasitic infections such as malaria
o Meningitis
o Encephalitis
o Sinusitis
• Severe pain or shock
• Trauma, especially post-concussion which needs close monitoring
• 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) which include:
o Gastro-intestinal disease such as gastritis, peptic ulcer, stomach cancer, gut obstruction, appendicitis and mesenteric adenitis
o Disease of the liver or gallbladder such as cholecystitis, hepatitis and cirrhosis
o Pancreatitis
o Heart diseases such as myocarditis, severe hypertension, heart attack (myocardial infarction) and congestive heart failure.
o Brain conditions such as stroke (cerebrovascular accident), brain tumours, epilepsy and any condition when there is a lack of oxygen and nutrients getting to the brain.
o Certain endocrine problems (e.g. hyperparathyroidism, hyperthyroidism and diabetes mellitus) produce chemical imbalances that stimulate the vomiting centre
o The waste products that accumulate in the body with renal failure and other electrolyte disturbances can stimulate the vomiting centre in the brain
o Some drugs and hormones can stimulate the vomiting centre, causing nausea and vomiting. These include digoxin, morphine, estrogens, iron preparation and aminophyllin.
o Other conditions such as morning sickness, haemolytic anaemia, alcoholism and radiotherapy.
o Congenital malformations of the gastro-intestinal tract such as pyloric stenosis and gastro-oesophageal reflux, especially in the first six weeks of life.
Psychological and psychiatric causes of vomiting and nausea include:
• Attention- seeking in children
• Shock, for example after witnessing a traumatic incident
• Bulimia nervosa and self- induced vomiting
How vomiting and nausea progress
Nausea and vomiting are mild and self-limiting most of the time.
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, producing large quantities of saliva that contain a lot of mucus.
The person may also feel weak and sweaty. The glottis closes and breathing stops, which prevents the vomit from entering the lungs.
This is followed by an involuntary contraction of the stomach muscles during which the stomach contents are forcefully expelled through the mouth.
More severe cases of vomiting may cause fluid and electrolyte loss. In such cases it is not practical to do oral rehydration and treatment at home, so it may require being hospitalised to have intravenous therapy.
Reviewed by Dr Saville Furman, MBChB MFGP (SA). Family Physician, Part time lecturer in family medicine and primary care at UCT, Red Cross Children’s Hospital and Groote Schuur hospital, Cape Town. February 2015.
Previously reviewed by Prof Don du Toit.
