Fainting from hunger: what to know

Going without food can leave some people shaky, sweaty, weak, irritable, dizzy, or unable to concentrate. Dehydration may add to the drop in blood pressure, especially after standing. People taking diabetes medicines can develop hypoglycaemia when food intake changes, but hunger alone should not be assumed to explain every blackout.

Anaemia, an abnormal heart rhythm, and other conditions can also cause fainting. The timing of meals is useful information, yet the setting, posture, warning symptoms, medicines, and recovery all matter.

At the first warning, sit or lie down to prevent a fall. If the person is fully awake and can swallow, a quick source of carbohydrate may help when low blood glucose is suspected, followed by a balanced snack or meal. Do not give food or drink to an unconscious, confused, or vomiting person. Check breathing and place an unconscious breathing person on their side while seeking help.

Call emergency services for a prolonged blackout, seizure, confusion, chest pain, breathing difficulty, serious injury, fainting during exercise, or failure to recover normally. Seek prompt medical advice after a first episode, repeated events, fainting without warning, or symptoms despite eating. Diabetes, pregnancy, heart disease, and medicines affecting glucose or blood pressure warrant earlier contact.

Ask whether glucose testing, blood counts, blood pressure checks, or heart monitoring are appropriate. Share meal timing, fluid intake, alcohol, exercise, medicines, symptoms before the event, and how quickly you returned to normal.