Nausea and Vomiting

What is nausea?

• Feeling of uneasiness of the stomach that often comes before vomiting

• Unpleasant, salivation, sweating, dizziness, tachycardia

What is vomiting?

• Forcible voluntary and involuntary emptying of stomach contents through the mouth

• Reflex act of expulsion of gastric contents through the mouth

• Coordinated by somatic nervous system

What is regurgitation?

• return of oesophageal or gastric contents into hypopharynx

Causes of N+V?

• intracranial

  • migraine

  • brain tumour

  • concussion

  • headaches

• vestibular

  • motion sickness

  • labyrinthitis

• endocrine/metabolic

  • pregnancy

  • uraemia

  • DKA

  • hyperthyroidism

• radiotherapy

• psychogenic

• drug induced

• GI

  • bowel obstruction

  • milk allergy

  • ulcers

  • gallbladders

  • gastroparesis

• surgery

• bacterial infections

• drugs

• chemotherapy

• fluid imbalance

How is vomiting controlled in the body?

• By a coordinated reflex controlled by the brain, triggered by signals from multiple pathways.

Role of the cerebral cortex in nausea and vomiting?

• involved in emotion, anxiety, stress, memory

• Vomiting triggered by sight, smell, fear, pain, emotional stress

What is the chemoreceptor trigger zone (CTZ)?

• Located in the medulla, outside the blood–brain barrier

• Detects chemicals in the blood

What activates the CTZ?

• Drugs, toxins

• Metabolic disturbances
  → Signals brain to induce vomiting

Clinical significance of the CTZ?

• Explains why many drugs cause nausea and vomiting.

Role of the vestibular labyrinths in N&V?

• Balance and motion sensing

• Responsible for motion sickness

Key neurotransmitters in vestibular‑induced vomiting?

• Histamine (H₁) and acetylcholine (muscarinic) receptors.

What are visceral stimuli in N&V?

• signals from:

  • Stomach

  • Intestines

  • Liver

  • Pancreas

  • Peritoneum

What visceral changes trigger nausea and vomiting?

• Irritation, distension, inflammation, infection.

What is chemotherapy induced N+V?

• can be intense, unrelenting, physically exhausting and emotionally distressing

• affects daily functioning, sleep, appetite, mental wellbeing

• results in patients refusing treatment

• physicians may delay treatment is N+V uncontrolled, patient dehydrated, electrolyte imbalance and nutritional status deteriorates

Complications of N+V?

• distress

• alkalosis

• mucosal damage

• oesophageal rupture

• aspiration

How is nausea and vomiting usually managed?

• Often self‑limiting; treat underlying cause and provide supportive care.

Complications of prolonged vomiting?

• Dehydration

• Malnutrition

• Metabolic alkalosis

• Hyponatraemia

• Hypokalaemia

Which groups are at highest risk of complications?

• infants

• children

Key signs of dehydration to look for?

• increased thirst

• dry lips and mouth

What underlying causes of N&V should be addressed?

• Migraine / headache

• Fever

• Dehydration

• Pregnancy

• Drug‑related causes

General principles of N&V management?

• Treat underlying cause

• Non‑pharmacological measures

• Symptomatic relief

• Manage complications

• Ensure adequate hydration

When are antiemetic drugs used?

• When the cause is known → use targeted therapy.

Main drug classes used to treat nausea and vomiting?

• Antihistamines

• Antimuscarinics

• Histamine analogues

• Dopamine receptor antagonists

• 5‑HT₃ (serotonin) receptor antagonists

• Steroids

• Nabilone

When to refer?

• poisoning suspected

• patient vomiting for >24hrs

• neonate <1 month

• blood is seen

  • Bright red or coffee ground appearance

• complaints of severe abdominal pain, headache, stiff neck

• signs of dehydration

  • dry mouth

  • infrequent urination

  • dark urine