Nausea and Vomiting

Vomiting

Contraction of abdominal muscles and respiratory muscles; GI irritation; vestibular sensation - motion sickness; drugs and toxins reaching the area postrema in the brain

The conscious sensation of feeling like you are going to vomit, often felt in the back of the throat or stomach

Pallor; cold sweats; reduced gastric tone

Dehydration; electrolyte imbalances; metabolic alkalosis; malnutrition

Recurrent episodes of severe, rapid-onset vomiting lasting from hours to several days, with symptom-free intervals between episodes

GI irritation or distension activates sensory receptors which communicate to the NTS via sensory afferent nerves; blood-borne pathways - drugs, toxins, hormones and inflammatory mediators stimulate the area postrema, which communicates with the NTS; vestibular pathway - abnormal movement activates vestibular nuclei which communicate with the brainstem

GI/vagal pathway; blood-borne pathway; vestibular pathway

Motion sickness; drugs and toxins; GI irritation or infection; pregnancy; metabolic disturbances; raised intracranial pressure

A condition caused by conflicting sensory information from the visual, vestibular and proprioceptive systems, activating vestibular pathways that stimulate the vomiting centre

Antihistamines; behavioural measures such as looking at the horizon

Block H1 receptors in vestibular pathways and reduce nausea and vomiting, particularly in motion sickness

5-HT3 receptor antagonists block serotonin signalling from the GI tract and vagal afferents to the vomiting centre

Reduce nausea and vomiting, particularly chemotherapy-induced nausea and vomiting; the exact mechanism is not fully understood

Block substance P at NK1 receptors in the brainstem, reducing nausea and vomiting

An atypical antipsychotic that blocks multiple receptors, including dopamine and serotonin receptors, and is used to prevent chemotherapy-induced nausea and vomiting

A combination of a 5-HT3 receptor antagonist, an NK1 receptor antagonist, dexamethasone and olanzapine

A single antiemetic such as dexamethasone or a 5-HT3 receptor antagonist, depending on the chemotherapy regimen

Block D2 receptors in the chemoreceptor trigger zone, reducing nausea and vomiting

Activate CB1 receptors to reduce nausea and vomiting, particularly in chemotherapy-induced nausea and vomiting

A condition associated with prolonged cannabis use, causing recurrent episodes of severe nausea and vomiting; symptoms may temporarily improve with hot showers

Nausea and vomiting that occur after surgery, often as a result of anaesthesia, opioids and surgical factors

Anaesthetic agents; opioid analgesics; surgical stimulation; vestibular stimulation; activation of the chemoreceptor trigger zone

Female sex; non-smoking status; history of motion sickness or postoperative nausea and vomiting; postoperative opioid use; longer duration of surgery

5-HT3 receptor antagonists such as ondansetron; corticosteroids such as dexamethasone; dopamine antagonists; antihistamines; adequate hydration and reduction of opioid use

Severe, persistent nausea and vomiting during pregnancy, leading to dehydration, electrolyte disturbances and weight loss

Octreotide

Prokinetic drugs such as metoclopramide, domperidone and erythromycin

The sense of the internal state of the body, including sensations from internal organs such as the gut

Delayed gastric emptying without mechanical obstruction, usually due to impaired gastric motility

Gastric emptying scintigraphy is the standard test; a solid meal is eaten and gastric emptying is measured over several hours