Digestive health centre

Nausea and vomiting

Nausea is an uneasiness in the stomach that often precedes vomiting. Vomiting is the forcible voluntary or involuntary emptying ('throwing up') of stomach contents through the mouth.

What causes nausea or vomiting?

Nausea and vomiting are not diseases, but they are symptoms of many conditions, such as:

Motion (travel) sickness (for example, car sickness) or seasickness
Early stages of pregnancy (nausea occurs in approximately 50% - 90% of all pregnancies, vomiting in 25%-55%)
Medication-induced vomiting
Intense pain
Emotional stress (fear)
Gall bladder disease
Food poisoning
Infections (such as 'stomach flu')
Overeating
A reaction to certain smells or odours
Heart attack
Concussion or brain injury
Brain tumour
Ulcers
Some forms of cancer
Bulimia or other psychological illnesses
Gastroparesis (delayed gastric emptying - a condition often found in people with diabetes)

The causes of vomiting differ according to age. For children, vomiting is often due to a viral infection, food poisoning, a milk allergy, motion sickness, overeating or excess feeding, coughing, blocked intestines or illnesses in which the child has a high temperature.

The timing of the nausea or vomiting can indicate the cause. When it happens shortly after a meal, nausea or vomiting may be caused by food poisoning, gastritis (inflammation of the stomach lining), an ulcer or bulimia. Nausea or vomiting one to eight hours after a meal may also indicate food poisoning. However, certain food-borne bacteria, such as salmonella, can take longer to produce symptoms.

Is vomiting harmful?

Usually vomiting is harmless, but it can be a sign of a more serious illness. Some examples of serious conditions that may result in nausea or vomiting include concussion, meningitis (infection of the membranes covering the brain), intestinal blockage, appendicitis and brain tumours.

Another concern is dehydration. Adults have a lower risk of becoming dehydrated because they can usually detect the symptoms of dehydration (such as increased thirst and dry lips or mouth). Children have a greater risk of becoming dehydrated, especially if they also have diarrhoea, because young children are often unable to communicate the symptoms.

Adults caring for sick children need to be aware of these visible signs of dehydration: dry lips and mouth, sunken eyes, and rapid breathing or pulse. In infants, also watch out for reduced urination and a sunken fontanelle (soft spot on top of the baby's head).

Recurrent vomiting in pregnancy can lead to a serious condition called hyperemesis gravidarum, where the mother may develop fluid and mineral imbalances that can endanger her life or that of her unborn child.

When to seek medical advice about nausea and vomiting

Seek medical advice about nausea and vomiting:

If the nausea lasts for more than a few days or if there is a possibility that you are pregnant.
If home treatment is not working, there is dehydration - or a known injury (such as a head injury) or infection has occurred that may be causing the vomiting.
Adults should seek medical advice if vomiting lasts for more than 24 hours, especially if accompanied by diarrhoea, or if there are signs of dehydration.
Seek medical advice if your infant or child under six years old has vomiting lasting more than a few hours, there is diarrhoea, signs of dehydration occur, there is a temperature higher than 38C (100.4F), or if the child hasn't urinated for six hours.
Seek medical advice if a child over six has vomiting, with or without diarrhoea, lasting more than 24 hours, there are signs of dehydration, there is a temperature higher than 38C (100.4F) or the child hasn't urinated for six hours.

You should seek immediate medical care if any of the following situations occur with vomiting: