What to Eat When Your Stomach Feels Off: Fluids, Plain Food, Red Flags
- The NHS says vomiting usually stops within 1 or 2 days and diarrhoea within 5 to 7 days, and advises eating when you feel able to.
- The US National Institute of Diabetes and Digestive and Kidney Diseases states that research shows a restricted diet does not help treat viral gastroenteritis, and most experts do not recommend fasting.
- The BRAT diet (bananas, rice, apple sauce, toast) is no longer routinely recommended: a CDC report called it "unnecessarily restrictive". Those four foods are fine to eat, but not as the whole menu for days.
- UK guidance is 30g of fibre a day and most adults average about 20g, so rebuild fibre over a couple of weeks once the stomach has settled, not during the upset.
- Blood in vomit or stools, severe pain, signs of dehydration, vomiting for more than 2 days or diarrhoea for more than 7 days all need medical advice, not a food plan.
"Gut reset" is a marketing phrase. Search for it and you will be offered juice cleanses, powders and a 21-day protocol with a payment page. What most people typing it want is simpler: their stomach has felt wrong since last night, and they would like to know what to put in it today.
This guide covers that short window, a day or two of mild upset such as nausea, a loose stomach or a bug that is going round the office.
It sets out what the NHS and the main US health bodies say about fluids and food, where they disagree, and the symptoms that mean you should stop reading articles and speak to someone qualified.
Who is this guide for, and who is it not for?
It is for otherwise well adults with a mild upset that started recently and is already easing or holding steady. Most of these episodes are viral, pass without treatment and need rest, fluids and patience.
It is not for babies and young children, who dehydrate faster and have their own NHS guidance. It is also not enough on its own if you are pregnant, over 65, have a weakened immune system, or live with diabetes, kidney disease or inflammatory bowel disease.
In those cases get advice early, from a pharmacist, GP or NHS 111 in the UK, or your doctor in the US. The same applies if stomach trouble has been coming and going for weeks. That is a pattern for a clinician to look at, and no list of plain foods will explain it.
What should you drink first?
Fluid is the priority because vomiting and diarrhoea take water and salts out faster than usual. The NHS advice on diarrhoea and vomiting is to stay at home, rest and drink lots of fluids such as water or squash (diluted fruit cordial, for US readers).
Dark, strong-smelling urine and peeing less than usual are the signs of dehydration to watch for. A pharmacist can supply oral rehydration sachets, a powder you mix with water that replaces salts as well as fluid.
In the US, the NIDDK treatment guidance lists water, broths, sports drinks and fruit juices for adults, adds that saltine crackers help replace electrolytes, and says older adults, people with a weakened immune system and anyone with severe diarrhoea should use oral rehydration solutions.
If vomiting is the main problem, the Mayo Clinic suggests stopping solid food for a few hours and sucking ice chips or taking small, frequent sips.
The two countries differ on one point. The NHS says not to have fruit juice or fizzy drinks because they can make diarrhoea worse. NIDDK includes fruit juice in its list of fluids, while warning elsewhere that drinks with a lot of simple sugar can aggravate symptoms in some people.
The cautious reading is to make water, broth and rehydration drinks the main fluids, and keep juice small and diluted if you have it at all.
What should you eat for the first day or two?
Less than you might expect has been proven here. The NHS line is short: eat when you feel able to, and it may help to avoid foods that are fatty or spicy.
The NIDDK page on eating during viral gastroenteritis goes further and says that when appetite returns you can usually go back to your normal diet, even if you still have diarrhoea.
So plain food is a comfort measure. It is easier to face, and it is less likely to make nausea worse, but it does nothing to the bug itself.
The Mayo Clinic's examples of foods to start with are soda crackers, soup, oats, noodles, bananas and rice. Eggs, toast, plain potatoes, chicken and yoghurt (if dairy is sitting well) are reasonable additions once you are hungry.
| Stage | Drink | Eat |
|---|---|---|
| Actively being sick | Ice chips or a mouthful of water every few minutes | Nothing for a few hours. Forcing food down does not help |
| Settling (often later on day 1) | Water, weak squash, clear broth, oral rehydration drink if urine is dark | A few crackers, dry toast, half a banana, plain rice |
| Appetite returning (day 2) | Keep the fluids going. Tea and coffee can wait another day | Porridge, soup with noodles, scrambled egg on toast, a jacket potato, plain chicken |
| Feeling close to normal | Usual drinks, alcohol last | Normal meals, with rich, fried and heavily spiced dishes brought back last |
NIDDK names four groups that make symptoms worse for some people: caffeinated drinks, high-fat foods such as fried food and pizza, food and drink with a lot of simple sugar, and milk products, because a bug can leave you temporarily less able to digest lactose.
The Mayo Clinic adds alcohol, nicotine and highly seasoned food. None of these is forbidden. If a cup of tea is the only thing you fancy, have the tea.
One practical note from the NHS that gets overlooked: stay off work, and keep children off school, until at least 2 days after the vomiting or diarrhoea has stopped. These bugs spread easily around a household, so soap and water at the sink is worth the effort.
Is the BRAT diet still recommended?
Not as a diet. BRAT stands for bananas, rice, apple sauce and toast, and for decades it was standard advice, especially for children. A CDC report on managing acute gastroenteritis described it as "unnecessarily restrictive" and said it can provide suboptimal nutrition for a recovering gut.
The Cleveland Clinic now states plainly that it is no longer recommended, because it is short of protein, fibre, calcium and vitamin B12, and notes that the American Academy of Pediatrics considers it too restrictive for children with diarrhoea.
The four foods themselves are fine. The problem was the rule that you should eat only those for days. For an adult, a day or so of toast and bananas at the worst point does no harm. After that, a wider plate helps recovery more than a narrower one.
When should you get medical advice?
Symptoms that need advice, not a food plan
In the UK, the NHS says to call 111 if you keep being sick and cannot keep fluid down, if you have bloody diarrhoea or bleeding from the bottom, if diarrhoea lasts more than 7 days or vomiting more than 2 days, or if you still have signs of dehydration after using oral rehydration sachets.
Call 999 or go to A&E if you vomit blood or something that looks like ground coffee, have green vomit, have a sudden severe tummy ache or headache, have a stiff neck and pain when looking at bright lights, or may have swallowed something poisonous.
In the US, NIDDK advises adults to see a doctor right away for diarrhoea lasting more than 2 days, six or more loose stools in a day, frequent vomiting, high fever, or severe pain in the abdomen or rectum.
The same applies to stools that are black and tarry or contain blood or pus, symptoms of dehydration, or a change in mental state such as unusual irritability or lack of energy. Call 911 in an emergency.
Separately from any bug: the NHS asks you to see a GP about changes in your poo that are not normal for you (looser, more or less often, constipation), blood in your poo, bleeding from your bottom, tummy pain, or losing weight without trying.
Other conditions can cause the same symptoms, which is the reason to have them checked instead of managing them with diet changes at home.
Note that the US threshold for diarrhoea is shorter than the UK one, 2 days against 7. If you are unsure which applies to you, take the earlier one.
How do you get back to normal eating?
Once you are eating ordinary meals without trouble, the most useful long-term change for digestion is the unexciting one: more fibre. The NHS gives the UK government target as 30g a day and says most adults eat about 20g.
US dietary guidelines, as summarised by the Mayo Clinic, use 14g of fibre for every 1,000 calories, which works out at about 28g on a 2,000-calorie day.
Do not try to close that gap in the week after a stomach bug. The Mayo Clinic advises adding fibre gradually over a few weeks, because a sudden jump causes gas, bloating and cramps, and drinking enough water as you go.
The NHS gives worked examples of what 30g looks like in real meals, which is more helpful than a list of grams per 100g.
| Meal | What is on the plate | Fibre |
|---|---|---|
| Breakfast | 2 slices of wholemeal toast with peanut butter, then a medium orange | About 8.3g |
| Lunch | Wholemeal spaghetti with a lentil and tomato sauce | About 11g |
| Dinner | Grilled chicken breast, a baked potato with the skin on, carrots and green beans | About 11.2g |
| Total | Three ordinary meals, no supplements or bran sprinkled on anything | About 30.5g |
If you are at the typical 20g, a sensible pace is one change a week: wholemeal bread in week one, a tin of lentils or beans (canned beans count) in a midweek dinner in week two, potato skins left on in week three.
If money is tight, our guide to healthy eating on a tight budget has more on building cheap meals around staples like these.
People with irritable bowel syndrome or inflammatory bowel disease should take fibre advice from their own clinician or dietitian, because the general target does not suit everyone.
Do gut reset cleanses and probiotics work?
Cleanses and detoxes
The US National Center for Complementary and Integrative Health reviewed the research on detoxes and cleanses and found only a small number of studies, of low quality. It quotes a 2015 review which concluded there was no compelling research to support detox diets for weight management or for eliminating toxins.
It also lists harms: unpasteurised juices can make people sick, programmes that include laxatives can cause diarrhoea and dehydration, and the FDA and FTC have acted against detox products containing hidden ingredients.
Put those side effects next to the reason you came here. A product that can cause diarrhoea is an odd purchase for someone whose stomach is already upset.
Probiotics
The evidence is better than for cleanses, and still thinner than the supplement aisle implies. The NHS says there is some evidence probiotics may help in some cases, such as easing some symptoms of irritable bowel syndrome, but little evidence to support many of the health claims made for them.
Because they are sold as food and not medicine, nobody checks that a product contains the bacteria on the label, contains enough of them, or that they survive as far as your gut.
In the US, the American Gastroenterological Association's 2020 clinical guideline did not recommend probiotics for most digestive conditions and advised patients to be sceptical of product labels.
NCCIH's summary is that in most instances it is still not known which probiotics are helpful and which are not, and that the risk of harm is greater in people who are seriously ill or have a compromised immune system.
If you like live yoghurt, kefir or sauerkraut, eat them as food. Nothing here suggests you need to buy capsules to recover from a two-day bug.
Questions readers ask
How long does an upset stomach usually last?
According to the NHS, vomiting usually stops within 1 or 2 days and diarrhoea within 5 to 7 days. NIDDK gives a range of 1 to 8 days for viral gastroenteritis depending on the virus, with norovirus typically lasting 1 to 3 days.
If yours is running longer than those windows, or getting worse instead of better, that is the point to call NHS 111 or your doctor.
Should you starve a stomach bug?
No. A few hours without solid food while you are actively vomiting is reasonable, and the Mayo Clinic suggests exactly that. Beyond those hours, NIDDK is clear that most experts do not recommend fasting or a restricted diet, and the NHS advice is to eat when you feel able to. Fluids should continue throughout, in small sips if necessary.
Is ginger or peppermint tea worth trying?
Neither appears in the NHS, NIDDK or Mayo Clinic guidance used for this article, so no claim is made for them here. As warm, caffeine-free fluids they count towards what you drink, and many people find them easier to sip than cold water. Treat them as a pleasant way to get fluid in and nothing more.
Sources
- NHS. Diarrhoea and vomiting. Reviewed 21 December 2023.
- National Institute of Diabetes and Digestive and Kidney Diseases. Eating, diet and nutrition for viral gastroenteritis; Treatment of viral gastroenteritis; Symptoms and causes of viral gastroenteritis.
- Mayo Clinic. Viral gastroenteritis (stomach flu): diagnosis and treatment; Chart of high-fiber foods.
- King CK, Glass R, Bresee JS, Duggan C; Centers for Disease Control and Prevention. Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recommendations and Reports. 2003;52(RR-16):1–16.
- Cleveland Clinic. BRAT diet: what it is and foods to eat.
- NHS. How to get more fibre into your diet; Probiotics; Symptoms of bowel cancer.
- National Center for Complementary and Integrative Health. "Detoxes" and "cleanses": what you need to know. Updated March 2025; Probiotics: usefulness and safety. Updated August 2019.
- Su GL, Ko CW, Bercik P, et al. AGA clinical practice guidelines on the role of probiotics in the management of gastrointestinal disorders. Gastroenterology. 2020.
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