Stomach bug for 3 days: what to know

A stomach bug lasting three days can still cause diarrhoea or nausea, but ongoing symptoms require careful hydration and review of warning signs. Many people improve gradually, yet persistent vomiting, worsening pain, fever, blood in stool or signs of dehydration mean you should contact a clinician.

Gastroenteritis can irritate the stomach and bowel, leading to loose stools, cramps, nausea, vomiting, reduced appetite and fever. Symptoms may not stop together: appetite can return before bowel movements become normal. Rotavirus infection is one possible cause, particularly in children. Ongoing symptoms can also reflect another infection, medicine effect or a condition that needs assessment, so the pattern matters more than the label stomach bug. Note whether you are improving, unchanged or getting worse.

Take frequent small sips of water or an oral rehydration drink, especially after each loose stool or episode of vomiting. Rest, wash hands carefully and avoid preparing food for other people while you have active diarrhoea. When able, choose simple foods and return to your usual diet gradually. Keep a record of urine, vomiting, stool frequency, pain and temperature. A pharmacist or clinician can advise on symptom medicines; do not give children adult products or use antibiotics left from another illness.

Seek same-day medical advice if diarrhoea or vomiting is not easing, you cannot keep fluids down, or you have fever, worsening abdominal pain or blood in stool. Get urgent help for faintness, confusion, severe weakness, severe pain, a swollen abdomen, very little urine or a dry mouth with increasing thirst. Children, older adults, pregnant people and anyone with kidney, heart or immune problems can become dehydrated more quickly and should seek advice earlier.

Does my symptom pattern fit gastroenteritis, or should another cause be checked? Which rehydration drink is appropriate for me? Do I need stool testing or treatment? What should I monitor overnight, and when should I return?