Gastroenteritis: symptoms, hydration and care

Gastroenteritis is inflammation of the stomach and intestines that commonly causes diarrhoea, vomiting, abdominal cramps, and fluid loss.

It is often called a stomach bug or stomach flu, although it is not influenza. The main immediate concern is replacing fluids and salts lost through diarrhoea or vomiting, especially when drinking is difficult.

Gastroenteritis commonly presents with loose or watery stools, nausea, vomiting, abdominal cramps, reduced appetite, and sometimes fever. The bowel may feel urgent and the abdomen can be noisy or bloated. Symptoms may start soon after exposure to an infection or contaminated food or drink.

Blood in the stool, a stiff neck, confusion, severe abdominal pain, or an inability to keep fluids down need urgent medical assessment. Infants, older adults, pregnant people, and people with conditions affecting immunity can become unwell more quickly.

Viruses are a frequent cause, including rotavirus in some settings. Bacteria and parasites can also cause gastroenteritis, often after food or water contamination. Infection may spread through unwashed hands, shared surfaces, close contact, or preparing food while unwell.

Not every episode has the same cause. Recent travel, meals, contact with someone who is ill, medicines, and the timing of symptoms help a clinician decide whether testing is useful.

Many episodes improve as the infection passes and fluid intake is maintained. Vomiting can settle before bowel movements return to normal. Ongoing diarrhoea, worsening pain, repeated fever, or inability to drink warrants medical review because the cause or level of fluid loss may need assessment.

The effect of gastroenteritis can be greater when fluid reserves are limited or the immune system is less able to handle infection. Young children, older adults, pregnant people, and people with kidney disease, diabetes, inflammatory bowel disease, or immune-suppressing treatment should seek advice early if symptoms are significant.

A clinician will ask about stool changes, vomiting, pain, fever, fluid intake, urine output, travel, food exposures, and sick contacts. Examination looks for signs of dehydration and abdominal tenderness. Stool, blood, or urine testing may be used when symptoms are severe, prolonged, bloody, or linked to a particular exposure.

The cornerstone of care is replacing fluid and salts. Take frequent small sips if vomiting makes larger drinks difficult. An oral rehydration solution can be useful because it contains a balanced mix of water, salts, and sugar. Continue food as tolerated, choosing simple familiar foods when appetite returns.

A clinician may recommend medicine for selected symptoms or investigate whether a specific infection needs targeted treatment. IV fluids may be needed when dehydration is significant or oral fluids cannot be kept down. Avoid using antibiotics or anti-diarrhoea medicines without medical advice, as they are not suitable for every cause.

Rest, keep a drink within reach, and monitor whether you are passing urine. Wash hands carefully after using the toilet and before handling food. Avoid preparing food for others while symptoms are active, and clean frequently touched bathroom surfaces to reduce spread within the household.

Dehydration can cause thirst, dry mouth, dark urine, reduced urination, dizziness, unusual sleepiness, or weakness. Urgent care is appropriate for signs of severe dehydration, bloody stool, severe persistent pain, confusion, or vomiting that prevents fluid replacement. A clinician should also assess symptoms that do not begin to improve.

Wash hands with soap and water after toileting, changing nappies, and before eating or preparing food. Keep raw foods separate from ready-to-eat foods, cook food thoroughly, and use safe drinking water. Do not share towels, cups, or utensils when someone in the home is unwell.

A GP can assess hydration, advise on testing, and decide whether treatment or referral is needed. Seek urgent care for severe dehydration, blood in stool, serious pain, or confusion. People with repeated episodes or symptoms that persist may need assessment for another digestive condition.