How soon after eating can food poisoning start?

Nausea, vomiting, cramps, diarrhoea, and fever can appear after a delay. The last meal is not necessarily the source: an earlier food or drink may have introduced the irritant. Note meals, drinks, travel, sick contacts, and the first symptom. Timing supports a clinical history but cannot confirm the cause alone. Explore [Food Poisoning](/conditions/food-poisoning/) and [Fever](/symptoms/fever/).

Begin replacing fluids when vomiting or diarrhoea starts. Take tiny, repeated sips; [Oral Rehydration Therapy](/treatments/acute-and-urgent-care/oral-rehydration-therapy/) may help replace fluid and salts. Rest, eat gentle foods when ready, wash hands thoroughly, and avoid preparing food for others while ill.

Get prompt medical advice if you cannot drink, symptoms worsen, or you remain unwell. Emergency assessment is needed for fainting, confusion, severe abdominal pain, blood in stool or vomit, or severe dehydration. Do not delay care because the meal was recent or symptoms appeared later. [IV Fluid Therapy](/treatments/acute-and-urgent-care/iv-fluid-therapy/) may help when drinking is not enough.

Tell your doctor what you ate, when symptoms began, recent travel, ill contacts, medicines, and health conditions; ask whether testing or treatment is appropriate.