What should you know about passing out and vomiting?

Repeated vomiting removes fluid and salts, which can lower blood pressure and make a person faint, particularly when they stand. Pain, straining, fever, and the illness causing the vomiting can also trigger a reflex faint. Food poisoning and gastroenteritis commonly cause vomiting with weakness or dizziness. Migraine can bring nausea and vomiting, while gallstones or pancreatitis may cause prominent upper-abdominal pain. Meningitis is a serious possibility when vomiting occurs with severe headache, stiff neck, fever, rash, or confusion.

The timing matters: note what was eaten, how often vomiting occurred, whether there was diarrhoea, and whether the person fully recovered.

Lay an unconscious breathing person on their side so vomit is less likely to block the airway. Do not give food, drink, or medicine until they are awake and able to swallow. Once alert, offer small frequent sips of an oral rehydration drink or water, and rise slowly. Avoid driving while dizzy. Keep a record of fluids, urine, pain, fever, and vomiting.

Call emergency services for trouble breathing, failure to wake, confusion, a stiff neck, severe headache, severe abdominal pain, blood or green vomit, a head injury, or signs of severe dehydration such as very little urine. Seek prompt care when vomiting prevents fluids staying down, fainting repeats, or dizziness persists.

Ask whether you need fluid and salt replacement, examination for abdominal or neurological causes, or tests. Tell the clinician about recent meals, travel, medicines, pregnancy possibility, fever, pain, and urine output.