Vomiting is one of the commonest reasons for an out-of-hours call – especially for children. While most cases are self-limiting and benign, the possible causes are numerous and the symptoms can herald serious pathology. Careful assessment is required, together with a willingness to review and admit if the diagnosis remains unclear.

Published: 1st August 2022 | Updated: 15th August 2022

Differential diagnosis

Common Diagnoses

  • Gastroenteritis
  • Acute Vestibular Neuronitis (and Some Other Causes of Acute Vertigo)
  • Upper Respiratory Tract Infection (URTI) (in Children, Especially with Marked Coughing)
  • Pregnancy
  • Appendicitis and Other Causes of the Acute Abdomen

Occasional Diagnoses

  • Hyper- and Hypoglycaemia
  • Intestinal Obstruction
  • Pyelonephritis
  • Ureteric Calculus
  • Migraine
  • Medication (e.g. Antibiotics and Cytotoxics)

Rare Diagnoses

  • Gastroduodenal Disease (e.g. Pyloric Stricture or Stenosis, Du, Carcinoma)
  • Meningitis
  • Cerebral Haemorrhage
  • Bulimia Nervosa
  • Severe Constipation
  • Raised Intracranial Pressure (e.g. Tumour)
  • Renal Failure
  • Acute Glaucoma

Ready reckoner

Key distinguishing features of the most common diagnoses

GastroenteritisVestibular NeuronitisURTI (Child)PregnancyAcute Abdomen
Mainly Mornings No No NoYes No
With DiarrhoeaYes NoPossible NoPossible
Nystagmus NoYes No No No
Bowel Sounds Increased?Yes No No NoPossible
Tender Abdomen?Possible NoPossible NoYes

Possible investigations

Likely: None.

Possible: Urinalysis, MSU, pregnancy test, blood glucose, FBC, U&E.

Small Print: Lumbar puncture, abdominal X-rays, renal imaging, OGD, CT scan.

  • Urinalysis: High specific gravity suggests dehydration; glucose and ketones indicate hyperglycaemia; blood, pus cells and nitrites suggest UTI (confirm with MSU); blood alone might indicate a renal stone.
  • Pregnancy test: To confirm or reveal pregnancy.
  • Blood glucose: Will confirm hypo- or hyperglycaemia.
  • U&E: May be deranged by vomiting; may also reveal underlying renal failure.
  • FBC: Raised WCC suggests underlying infection or inflammation. Haemoglobin (Hb) may be reduced in malignancy. Raised platelets associated with oesophageal or stomach cancer.
  • Lumbar puncture, renal imaging, abdominal X-rays, OGD and CT scans: Required in a few cases depending on the clinical picture and invariably arranged by the relevant specialist.

Top Tips

  • Vomiting in children tends to be presented early, when it may be difficult to give a definite diagnosis. Be honest about this and make sure that parents know to call you again if the symptom doesn’t settle or other ‘alarm’ symptoms develop – or arrange a definite time for follow-up.
  • Remember to look for both the cause (i.e. the aetiology) and the effect (i.e. possible dehydration) – especially in the very young and the very old, when the history may be difficult to obtain and the effects of fluid loss more marked.
  • Check to see if the patient is on any medication. This may be causing the vomiting, or it may have serious implications for management (e.g. steroids).
  • Don’t forget pregnancy as a cause – the patient may be ‘ignoring’ the possibility.

Red Flags

  • Unless the diagnosis is obviously migraine, beware the patient with vomiting and a headache – think of meningitis, subarachnoid haemorrhage or raised intracranial pressure.
  • Do not treat empirically with anti-emetics – these may mask the true diagnosis or cause diagnostic confusion via side effects.
  • Have a low threshold for admitting diabetics. Whatever the cause of the vomiting, their diabetes is liable to become uncontrolled.
  • Look for acid dental erosion as a clue to bulimia in recurrent vomiting.
  • Gastroenteritis should cause increased bowel sounds. In the patient with abdominal pain and vomiting, if bowel sounds are absent or scanty, the diagnosis is likely to be an acute abdomen.
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Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.