For patients · Reading time 6 minutes · Version 1.0 · Translation of the German page, medically reviewed on 7 October 2026 · the German version is authoritative · Diese Seite auf Deutsch

Stomach bug: drinking is the treatment

Vomiting and diarrhoea are almost always caused by viruses and are over after one to three days. It only becomes dangerous if the body dries out. Here you will find how to recognise that, how much you need to drink and what belongs in the glass. Cola and pretzel sticks do not.

The essentials in three sentences

  1. Drink in small sips, spread over the day, with salt and a little sugar in it.
  2. Eat as soon as you have an appetite. Starving tends to prolong the diarrhoea.
  3. Blood in the stool, high fever, nothing stays down, hardly any urine: then come to the practice today.

1

Does this belong at the practice? The signpost

These signs are rare. If one applies, someone should take a look.

Tick whatever applies. If nothing applies, leave everything blank.

No warning sign: an ordinary stomach bug

Unpleasant, but not dangerous. The most important treatment is drinking. Get in touch if a warning sign appears or if it is no better after three days.

Your ticks are neither stored nor sent anywhere. This list does not apply to babies and small children: with vomiting and diarrhoea, please come to the practice the same day.

2

What caused it, and how long does it last?

The three most common causes. Which one it was is usually guesswork, and for the treatment it hardly matters.

Noroviruses

The most common cause in adults, especially in winter

Onset
12 to 48 hours after infection
Duration
1 to 3 days
Typical
Projectile vomiting, then diarrhoea, highly contagious

Rotaviruses

Mainly small children, adults less often

Onset
1 to 3 days
Duration
3 to 7 days
Typical
Watery diarrhoea, fever

Bacteria from food

Campylobacter, salmonella; poultry, raw eggs, raw milk

Onset
6 hours to 3 days
Duration
3 to 7 days
Typical
Cramping abdominal pain, fever, sometimes blood in the stool

3

How much to drink? The calculator

“Drink plenty” is not a number. Here is one.

Today in total

3.2 l

16 glasses of 200 ml

Per waking hour

200 ml

just under a glass

When vomiting

2

sips every 10 minutes

This is a rule of thumb from general practice for an otherwise healthy adult, not a study figure. It does not apply with heart or kidney failure: then please call, the amount has to be set by a doctor.

What belongs in the glass

Oral rehydration solution from the pharmacy

Well established

Water, salt, sugar and potassium in the right proportions. The sugar is not a luxury: it helps the gut absorb the salt and with it the water.

The home recipe

Well established

One litre of boiled water, six level teaspoons of sugar, half a level teaspoon of salt. Plus a glass of orange juice or a mashed banana for the potassium. Tastes bland, works.

Tea with a little sugar and a pinch of salt, diluted broth

Some studies, small effect

Better than water alone, because there is salt in it. Broth provides sodium, tea with sugar provides energy.

Water only

Few, small studies

Better than nothing, but without salt it stays in the body less well. With severe diarrhoea it is not enough.

Cola and salted pretzel sticks

More likely to harm

The classic is wrong. Cola has far too much sugar, which draws water into the gut and makes the diarrhoea worse. Pretzel sticks provide salt but no potassium. If you like them, you may eat them, but with the rehydration solution.

4

What helps, and what does not

Ordered by how well it is supported by evidence. Two surprises included.

Drink in small sips

Well established

The treatment. A few sips every ten minutes rather than a glass at once, which otherwise comes straight back. Amount according to the calculator above.

Eat as soon as you have an appetite

Well established

There is no reason to starve. Light and small: rusks, rice, potatoes, banana, porridge, broth with noodles. Whatever you tolerate is right. Fatty, spicy food, alcohol and lots of raw vegetables only once it is over.

Milk with care

Some studies, small effect

After diarrhoea the gut tolerates less milk sugar for a few days. Yoghurt is usually fine, a glass of milk not necessarily.

Rest, but not bed rest

Some studies, small effect

The body needs strength for drinking and recovering. Move about as much as you can.

Loperamide as per the package leaflet

Some studies, small effect

Stops the diarrhoea for a journey or an appointment, but cures nothing, and the gut clears the germs more slowly. Available without prescription for adults and young people from twelve: 4 mg to start, then 2 mg after each loose stool, at most 12 mg a day, without medical advice for at most two days. Not with fever, not with blood in the stool, not after antibiotics, not for children under twelve.

Probiotics

Not supported by Western studies

The large Cochrane review of 2020 with 12,000 participants found no difference: diarrhoea lasts just as long with probiotics as without. They do no harm, they only cost.

Charcoal tablets, healing clay

Not supported by Western studies

Supposedly bind toxins. For the ordinary infection there is no evidence, and they turn the stool black, which hides a warning sign.

Antibiotics

Not supported by Western studies

Useless against viruses, and with most bacterial diarrhoea they tend to prolong the shedding of germs. Only for certain germs or severe courses, after a stool sample and a doctor’s decision.

5

Not infecting others

Noroviruses need ten virus particles for an infection. One visit to the toilet spreads billions.

  1. 1Wash your hands, with soap

    After every visit to the toilet, before every meal, 20 to 30 seconds. Hand gel from your bag works poorly against noroviruses; soap and water work.

  2. 2Your own toilet, your own towel

    If possible. Clean the toilet and handles daily, with a cleaner that covers noroviruses, or simply thoroughly with soap. Laundry at 60 degrees.

  3. 3Stay at home for two days after the last vomiting or diarrhoea

    You remain contagious for that long. That applies to work, school and visits to older people.

  4. 4Nursery, school, food handling: please tell us

    Children under six may return to nursery only after two days without symptoms. Anyone who handles food at work may return only once the practice has cleared them. Both are regulated by law in Germany; tell us on the phone.

6

From other healing traditions

Further reading. Each item says how well it is supported by Western studies.

Ginger against nausea

Asia

Some studies, small effect

As tea or fresh. Effective in studies for nausea in pregnancy and after surgery; not specifically studied for stomach bugs, but harmless.

Grated apple

Europe

Few, small studies

The pectin binds water in the gut. Small studies in children show a slight effect. Suitable as light food in any case.

Black tea, blueberries

Europe

Few, small studies

Tannins tighten the lining of the gut. A home remedy for generations, hardly studied. Black tea also counts as fluid.

Chicken broth, rice water

everywhere

Some studies, small effect

Salt, water, a little starch: that is almost a rehydration solution. Rice water was the forerunner of the World Health Organization’s oral rehydration solution.

Fennel, caraway, aniseed

Europe, Middle East

Not supported by Western studies

Pleasant against bloating and cramps, no proven effect on how long the infection lasts.

Fasting "to rest the gut"

Europe

More likely to harm

The gut recovers faster when it has something to do. Eating as soon as you have an appetite tends to shorten the diarrhoea.

7

Quick check: what will you take away?

Five questions for anyone who likes. No marks.

1. What is the most important treatment for a stomach bug?

2. Cola and pretzel sticks for diarrhoea: a good idea?

3. How long are you contagious after a norovirus infection?

4. What do probiotics achieve for acute diarrhoea?

5. Your stool is black like tar. What do you do?

No marks, no time pressure. Your progress is kept on this device only.

What this page cannot do

It makes no diagnosis and replaces no examination. It applies to otherwise healthy adults. For babies, small children, pregnant women, people over 75 and those with heart, kidney or immune weakness, different rules apply: please get in touch early. This page is a translation of the German original, which is the medically reviewed version; where the two differ, the German text applies.

Version 1.0 · Translation of the German page, medically reviewed on 7 October 2026 · the German version is authoritative

Reviewed by Stefan Höhne, Facharzt für Allgemeinmedizin. Numbers, doses and emergency numbers are identical to the German version and checked automatically. If anything is unclear, the German text applies.

Sources: Collinson et al., Cochrane 2020 (probiotics); Freedman et al., NEJM 2018; World Health Organization (oral rehydration solution); Robert Koch Institute (noroviruses, contagiousness); German Infection Protection Act, sections 34 and 42. Medically responsible: Stefan Höhne, specialist in general practice (Facharzt für Allgemeinmedizin). This page is independent: no sponsor, no advertising, no brand names. All patient information (German)