Vomiting, and the nausea that usually precedes it, are some of the most common symptoms experienced by humans, and are almost unavoidable at some time in life. An enormous range of infections, gut diseases, liver disorders, brain conditions, glandular disorders, and even urinary tract abnormalities, as well as many other problems that cannot be easily categorised, can cause nausea and vomiting.
Gastroenteritis is the most common infective cause of vomiting and it is usually associated with diarrhoea. A viral infection is the normal cause, but bacteria may sometimes be responsible. The infection is passed from one person to another by close contact or on the breath, and usually occurs in epidemics, often in springtime.
The nausea and vomiting associated with sea sickness, car sickness and other motion induced forms of vomiting is due to an inability of the brain to co-ordinate what it is sensing from the balance mechanisms in the inner ears with what is being seen by the eyes. In a ship, the cabin appears to be perfectly still, while the balance senses movement. For this reason, watching the horizon while on the ship deck enables the brain to see the motion and reconcile the visual and balance senses.
Severe pain of any cause may result in nausea and vomiting as a reaction to the pain.
Other causes of nausea and vomiting include:
- meningitis (infection of the supporting membranes around the brain),
- many different bacterial and viral infections (e.g. cystitis, sinusitis),
- gastritis (inflammation of the stomach from acid irritation),
- mesenteric adenitis (infected lymph nodes in the abdomen),
- an increase in the pressure of the cerebrospinal fluid (CSF) which surrounds the brain and spinal cord due to ahead injury, tumour, cancer, abscess or infection in the brain or surrounding tissues.
Less common causes include:
- uraemia (kidney failure),
- intussusception (infolding of the gut on itself, usually in children),
- a reduction in the blood supply to the brain (from suffocation, near drowning, inhalation of smoke or toxic gases, narrowing of the arteries to the brain, or any form of heart failure),
- abnormalities of most glands (may affect the body’s chemical balances),
- poorly controlled diabetes,
- hyperthyroidism (overactive thyroid gland),
- altitude sickness,
- an anaphylactic reaction (immediate, severe, life-threatening reactions to an allergy-causing substance).
In infants, particularly boys, severe projectile vomiting may be due to pyloric stenosis (narrowing of the drainage valve from the stomach).
Many medications may have nausea and vomiting as a side effect.
There are many other rare conditions that may have nausea and vomiting as a symptom.
The management of nausea and vomiting involves identifying the cause, treating that if possible or using antiemetic medications (e.g. metoclopramide, prochlorperazine, promethazine).