Severe stomach flu

Stomach flu commonly refers to gastroenteritis, an illness involving diarrhoea, nausea, vomiting, abdominal pain, loss of appetite, and sometimes fever. Viruses such as rotavirus can cause it, although other infections and non-infectious problems can produce similar symptoms. Diarrhoea or vomiting can lead to dehydration when the body loses more fluid than it replaces.

Take frequent small sips of water or an oral rehydration drink; small amounts may stay down more easily than a large glass. Rest, eat simple foods when appetite returns, and avoid alcohol. Wash hands with soap and water, clean shared bathroom surfaces, and avoid preparing food for others while unwell. Do not use anti-diarrhoeal medicine for a child without professional advice, or when there is blood in stool or a fever. A clinician or pharmacist can advise on age-appropriate options and existing medicines.

Get prompt medical help if fluids will not stay down, urination becomes very limited, dizziness or confusion develops, the mouth is very dry, or the person becomes unusually sleepy. Urgent assessment is also needed for blood or black stool, severe or localised abdominal pain, repeated vomiting, a high or persistent fever, or worsening symptoms. Babies, older adults, pregnant people, and those with long-term conditions can become unwell from fluid loss more quickly.

Ask how much and what type of fluid replacement is suitable, whether testing is needed, which medicines to avoid, how to reduce spread at home, and what signs indicate dehydration or a complication.