Nausea
Nausea is the unsettled, queasy sensation that often precedes vomiting. It is not a disease in itself but a symptom, one that ranges from mildly inconvenient to debilitating depending on the underlying cause.
Key points
- Nausea itself is a symptom rather than an illness, signalling anything from a passing stomach upset to a more serious underlying cause.
- Common triggers include stomach infections, motion sickness, migraine, pregnancy, and certain medicines, with severity depending heavily on the cause.
- Antiemetics such as metoclopramide, domperidone, and prochlorperazine work by blocking the gut and brain signals that set off vomiting.
What triggers it
Triggers span a wide spectrum. Gastroenteritis is one of the most common culprits, with foodborne illness a frequent concern. Motion sickness affects many travellers on long ferry and bus journeys. Other common causes include pregnancy (especially in the first trimester), migraine, inner-ear disturbances, chemotherapy, and some medications.
Antiemetic medicines
Several medicines work by blocking the signals that set off the vomiting reflex. Metoclopramide and domperidone both act on dopamine receptors in the gut and brain to speed gastric emptying and reduce nausea, domperidone is particularly well tolerated because it has limited central nervous system penetration. Prochlorperazine is a phenothiazine antiemetic often used for more severe or prolonged nausea. All three sit within the broader digestive health category.
When to seek help
Most episodes of nausea settle within a day or two with rest and oral rehydration. Seek medical attention if nausea is accompanied by severe abdominal pain, signs of dehydration, blood in vomit, or lasts more than 48 hours without an obvious cause.