Stomach flu from norovirus: why soap and water work better than hand sanitiser

General information, not medical advice. With signs of dehydration (passing little urine, drowsiness, confusion), blood in the stool, high fever, or in babies, young children and frail older people: contact your GP or call 1733 outside office hours.

Especially in winter, stomach flu goes around in schools, care homes and families. In older children and adults, norovirus is the main cause. The virus is highly contagious, but in healthy adults stomach flu is usually over within a few days. Two things make the biggest difference: drinking enough and washing your hands with soap and water.

How stomach flu caused by norovirus runs its course

According to Sciensano, the Belgian institute for health, symptoms start 24 to 48 hours after infection. Typical are sudden diarrhoea, vomiting, stomach cramps, headache and a mild fever. Heavy vomiting is common. According to the Flemish guideline on infectious diseases, the symptoms disappear after 2 to 3 days in adults and after about a week in children.

Even when you feel well again, you keep shedding the virus for a long time. In stool this generally continues for 3 weeks after recovery. The virus spreads through unwashed hands, contaminated food and direct contact. Vomiting and flushing the toilet also release tiny droplets containing the virus into the air.

Drinking matters most

Vomiting and diarrhoea make you lose a lot of fluid and salts. The risk of dehydration is highest in older people and young children. So drink often, in small sips each time: water, tea, broth or a sports drink. If that does not work well, a solution of salts and sugars from the pharmacy, known as ORS, helps restore your fluid and salt balance. How much water you normally need per day is covered in a separate article.

You can eat: there is no need to fast. Small, light meals are easiest. Antibiotics do not help, because they do not work against a virus. An anti-diarrhoea medicine such as loperamide is not needed as standard and is not suitable for children under 6 or with fever or blood in the stool. Probiotics no longer work once you already have stomach flu.

When should you call your GP?

Watch for signs of dehydration: a lot of thirst, a dry tongue, passing no or little urine, drowsiness or dizziness. Confusion, fast breathing or a fast heartbeat are serious signals. Then call your GP straight away or, outside office hours, 1733.

Stomach flu at home: limiting the spread

Norovirus is tough. According to the Flemish guideline, comparable viruses survive for more than two weeks on surfaces. Ordinary cleaning products and many alcohol-based products struggle to make it harmless. What does help:

• Wash your hands with soap and water after every toilet visit and before preparing food. Hand sanitiser works less well against norovirus.
• Clean the toilet and places where someone has vomited with a chlorine-based product, such as diluted bleach.
• Close the toilet lid before flushing.
• Wash soiled bedding and clothes separately, at the highest possible temperature.
• Keep sick children at home if possible. If you work in the food sector or in care in an institution, only return to work 48 hours after you have recovered.

Getting back to exercise after stomach flu

The guidelines give no fixed rules on exercise after stomach flu. A reasonable rule of thumb from the editors: wait until you are eating and drinking normally again and the diarrhoea is over. Then start gently, with a walk or a short, light workout. You have lost fluid and salts, so drink well. How to approach this after a cold is described in the article on exercising with a cold.

Sources

• Gezondheid en Wetenschap (Cebam). Buikgriep (acute maagdarmontsteking). Last updated on 17 September 2026 (in Dutch).
• Gezondheid en Wetenschap (Cebam). Diarree veroorzaakt door microben. Last updated on 27 May 2025 (in Dutch).
• Sciensano. Norovirus. Accessed on 30 October 2026 (in Dutch).
• Departement Zorg, Flemish government. Richtlijn infectieziektebestrijding: calicivirusinfectie, norovirusinfectie. Version of August 2023 (in Dutch).