Fainting from food poisoning

Food poisoning may bring nausea, vomiting, diarrhoea, abdominal pain and fever. Losing fluid through the gut reduces the volume circulating in the bloodstream, while poor intake makes replacement harder. Standing can then cause a marked drop in blood pressure and faintness.

Fainting is not a routine symptom to dismiss. It may signal significant dehydration, particularly with very little urine, a dry mouth, intense thirst, worsening weakness or confusion. The illness can also need assessment if symptoms are severe or persistent.

Lie down as soon as you feel faint and have someone stay with you. When fully awake and able to swallow, take frequent small sips of an oral rehydration solution. Small amounts are often easier to keep down than a large drink. Rest, wash hands carefully and avoid preparing food for other people while you are unwell.

If you continue vomiting or cannot replace fluid by mouth, a clinician may assess you for treatment such as IV Fluid Therapy. Do not take anti-diarrhoeal or anti-vomiting medicine without checking that it is suitable for your symptoms.

Seek urgent help for fainting with confusion, severe abdominal pain, blood in vomit or stool, breathing difficulty, a serious injury, very little urine or inability to keep fluids down. Children, older adults, pregnant people and those with significant medical conditions can become dehydrated quickly and should get advice early.

Ask whether you need an examination for dehydration, testing for the cause of the illness, or supervised rehydration. Tell the clinician when vomiting and diarrhoea began, what you have managed to drink, how often you have urinated, and whether anyone else who ate the same food is ill.