Diarrhoea and vomiting are common symptoms in adults. They are unpleasant, inconvenient and sometimes worrying, but they are often caused by a short-lived stomach bug and improve within a few days. The main risk is dehydration, especially if you are losing fluid from both ends, cannot keep drinks down, are older, pregnant, frail, or have a long-term condition.
Most cases can be managed at home with rest, fluids and careful hygiene. But diarrhoea and vomiting can sometimes be a sign of food poisoning, norovirus, a urinary infection, a flare of a digestive condition, a medicine side effect, or a more serious problem that needs medical advice.
This guide explains the common causes of diarrhoea and vomiting in adults, what you can do at home, how to spot dehydration, how to avoid spreading infection, and when to contact a pharmacist, GP, NHS 111 or 999.
Important: Seek urgent medical advice if you have blood in your stool, black stool, blood in vomit, severe or worsening abdominal pain, signs of severe dehydration, confusion, chest pain, fainting, a stiff neck, a non-blanching rash, or you feel seriously unwell.
What do diarrhoea and vomiting mean?
Diarrhoea means passing looser or more watery stools than usual, often more frequently. Vomiting means being sick and bringing up stomach contents through the mouth. Some people have diarrhoea only, some have vomiting only, and some have both.
The NHS says diarrhoea and vomiting are common in adults, children and babies, are often caused by a stomach bug, and should usually stop in a few days. The most important thing is to drink plenty of fluids to avoid dehydration. You can read official NHS advice on diarrhoea and vomiting.
Although the cause is often minor, the pattern matters. Diarrhoea after a takeaway, vomiting after a meal, diarrhoea with fever, watery diarrhoea after contact with someone unwell, or persistent diarrhoea after travel may point in different directions.
Common causes of diarrhoea and vomiting in adults
There are many possible causes. The most common are infections, but medicines, alcohol, stress, digestive conditions and food intolerance can also play a role.
Common causes include:
- viral gastroenteritis, often called a stomach bug
- norovirus
- food poisoning
- traveller’s diarrhoea
- COVID, flu or another viral illness
- alcohol or rich foods
- medicine side effects
- antibiotic-associated diarrhoea
- irritable bowel syndrome
- inflammatory bowel disease flare
- coeliac disease or food intolerance
- anxiety or stress-related gut symptoms
- migraine, which can sometimes cause nausea and vomiting
- pregnancy, especially early pregnancy
If abdominal pain is one of your main symptoms, read our guide to abdominal pain by location. If fever is also present, see Fever in Adults: What Temperature Means and When to Worry.
Stomach bug or gastroenteritis
A stomach bug, also called gastroenteritis, is one of the most common causes of diarrhoea and vomiting. It is usually caused by a virus, although bacteria and parasites can also cause similar symptoms.
Symptoms may include:
- watery diarrhoea
- vomiting
- nausea
- stomach cramps
- mild fever
- headache or body aches
- loss of appetite
- tiredness
NHS Inform advises that sudden diarrhoea and vomiting in adults often needs rest, fluids and time, and that there is not always a specific treatment because the illness usually has to run its course. You can read more about gastroenteritis in adults.
Norovirus
Norovirus is a very contagious stomach bug. It can spread quickly in households, workplaces, schools, care homes, hospitals and shared accommodation.
Norovirus often causes sudden vomiting, watery diarrhoea, nausea, stomach cramps and sometimes fever, headache or aching limbs. Symptoms usually start quickly and can make you feel very unwell, but many people improve within a couple of days.
Because norovirus spreads easily, hygiene is very important. Wash hands thoroughly with soap and water, clean contaminated surfaces, wash soiled clothing or bedding, and avoid preparing food for others while you are unwell.
For a more detailed overview, see our guide to what norovirus is.
Food poisoning
Food poisoning happens when you eat food contaminated with harmful bacteria, viruses, parasites or toxins. Symptoms can start within hours or sometimes days, depending on the cause.
Food poisoning may cause:
- diarrhoea
- vomiting
- nausea
- stomach cramps
- fever
- headache
- body aches
- feeling weak or washed out
The NHS says food poisoning can usually be treated at home and symptoms usually get better within a week. The main priority is drinking fluids to avoid dehydration. See official NHS guidance on food poisoning.
Seek advice if symptoms are severe, if there is blood in your stool, if you cannot keep fluids down, if you have signs of dehydration, if you are pregnant, over 60, immunosuppressed, or if symptoms are not improving after a few days.
Traveller’s diarrhoea
Diarrhoea and vomiting after travel may be caused by contaminated food or water, unfamiliar bacteria, viruses or parasites. In many cases it is short-lived, but fever after travel or persistent diarrhoea should be taken seriously.
Get medical advice if you have diarrhoea or vomiting after travel and:
- you have a fever
- there is blood or mucus in your stool
- symptoms are severe or persistent
- you are dehydrated
- you have severe abdominal pain
- you recently travelled to an area where malaria or other serious infections are possible
- you are pregnant or immunosuppressed
Tell the clinician where you travelled, when symptoms started, what you ate or drank, whether anyone else was unwell, and whether you took antibiotics or malaria prevention tablets.
Medicine side effects
Some medicines can cause diarrhoea, nausea or vomiting. These include antibiotics, metformin, iron tablets, some painkillers, laxatives, some antidepressants, some heart medicines, and some weight-loss medicines.
Do not stop prescribed medicine without medical advice, especially if it is for a long-term condition. Speak to a pharmacist or GP if symptoms started soon after beginning a new medicine, changing a dose, or combining medicines.
If you are taking weight-loss medicines and have persistent vomiting, severe abdominal pain, dehydration, or cannot keep fluids down, seek medical advice. You may also find our guides to weight loss injections in the UK and online weight-loss jabs and safety useful.
Digestive conditions that can cause diarrhoea
Not all diarrhoea is caused by infection. If diarrhoea keeps coming back, lasts for weeks, or is linked with weight loss, blood, night-time symptoms or ongoing abdominal pain, a digestive condition may need to be considered.
Possible causes include:
- irritable bowel syndrome
- inflammatory bowel disease, including Crohn’s disease and ulcerative colitis
- coeliac disease
- food intolerance
- bile acid diarrhoea
- thyroid problems
- bowel infection that has not cleared
For more background, read our guides to digestive health symptoms, IBS, inflammatory bowel disease and coeliac disease.
How long do diarrhoea and vomiting usually last?
Vomiting often improves within 1 to 2 days. Diarrhoea may take a few more days to settle. With many stomach bugs, you should start to feel gradually better within a few days, although tiredness and a reduced appetite can last longer.
If diarrhoea lasts more than a week, vomiting lasts more than a couple of days, or symptoms are getting worse rather than better, seek medical advice.
Do not ignore persistent diarrhoea, especially if it comes with blood, unexplained weight loss, night sweats, fever, anaemia, severe pain, or a change in bowel habit that does not return to normal. Our guide to blood in stool explains one important red flag in more detail.
Dehydration: the main risk
When you have diarrhoea and vomiting, your body can lose fluid and salts quickly. This can lead to dehydration. Dehydration is more likely if you are vomiting repeatedly, have frequent watery diarrhoea, have a fever, are sweating, are not drinking enough, or are older or frail.
Signs of dehydration in adults include:
- thirst
- dry mouth or dry lips
- dark yellow or strong-smelling urine
- peeing less often than usual
- dizziness or lightheadedness
- feeling weak or unusually tired
- headache
- fast heartbeat
- confusion or disorientation in more severe cases
The NHS explains that dehydration happens when the body loses more fluid than it takes in, and it can become serious if not treated. See official NHS advice on dehydration.
For a fuller guide, read Dehydration Symptoms in Adults and Children.
Who is more at risk of dehydration?
Some adults need to be more careful because dehydration can happen faster or cause more problems.
Higher-risk groups include:
- older adults
- frail adults
- pregnant women
- people with diabetes
- people with kidney disease
- people with heart failure
- people taking water tablets or diuretics
- people who are immunosuppressed
- people who cannot drink enough or live alone
If you have kidney disease, heart failure or have been told to restrict fluids, ask a clinician what is safe for you. Do not suddenly drink very large amounts of water if you have been given a fluid restriction.
What to drink when you have diarrhoea or vomiting
Small, frequent sips are usually better than trying to drink a large glass at once, especially if you feel sick. If you vomit, wait a few minutes, then try again with small sips.
Useful options include:
- water
- oral rehydration solution from a pharmacy
- diluted squash
- clear soups or broths
- weak tea if tolerated
Oral rehydration sachets contain salts and sugar in the right balance to help replace what you lose. They can be especially useful if you are older, dehydrated, have ongoing diarrhoea, or are struggling to drink enough.
Avoid alcohol. It can worsen dehydration and irritate the stomach. Very sugary drinks may worsen diarrhoea in some people. If milk or coffee makes symptoms worse, pause them until you recover.
What should you eat?
You do not need to force food if you feel sick. Fluids matter more at first. When you feel able, try small amounts of plain, easy-to-digest food.
Examples include:
- toast
- rice
- bananas
- plain pasta
- crackers
- soup
- potatoes
- small portions of normal food as appetite returns
Avoid heavy, greasy, spicy or very rich foods until your stomach settles. Return to your normal diet gradually.
Should you take anti-diarrhoea medicine?
Some adults use anti-diarrhoea medicines such as loperamide for short-term symptom control, for example if diarrhoea is disrupting essential travel or work. However, these medicines are not suitable for everyone and are not always the right choice.
Avoid anti-diarrhoea medicines and seek advice first if you have:
- blood or mucus in your stool
- a high fever
- severe abdominal pain
- suspected food poisoning with severe symptoms
- recent antibiotic use
- inflammatory bowel disease
- diarrhoea that is not improving
A pharmacist can advise whether an over-the-counter medicine is suitable for your situation.
Should you take anti-sickness medicine?
Most vomiting from a stomach bug improves without prescription medicine. If vomiting is repeated and you cannot keep fluids down, medical advice may be needed, especially if you are dehydrated or have other red flags.
Do not take someone else’s anti-sickness medicine. Some medicines are not suitable for certain heart conditions, pregnancy, older adults, Parkinson’s disease, epilepsy or people taking specific medicines.
Antibiotics: are they needed?
Antibiotics are not usually needed for diarrhoea and vomiting because many cases are viral. Even many cases of food poisoning improve without antibiotics.
Antibiotics may be considered in certain situations, such as severe bacterial infection, some infections after travel, or in higher-risk patients. A clinician may request a stool sample if symptoms are severe, persistent, bloody, linked to travel, or part of an outbreak.
Taking antibiotics unnecessarily can cause side effects and can sometimes make diarrhoea worse.
How to avoid spreading diarrhoea and vomiting
Many stomach bugs spread very easily. Good hygiene helps protect others.
Practical steps include:
- wash hands often with soap and water
- do not rely only on hand gel, especially with norovirus
- clean toilet seats, flush handles, taps and door handles
- wash soiled clothing and bedding separately if needed
- avoid preparing food for others while unwell
- use separate towels if possible
- stay away from work, school or shared settings while symptoms are active
The NHS advises staying off school or work until you have not been sick or had diarrhoea for at least 2 days. This helps reduce the risk of passing infection to others.
When to see a pharmacist
A pharmacist can help if symptoms are mild to moderate and you are not severely unwell. They can advise on oral rehydration sachets, suitable pain relief, anti-diarrhoea medicines, nausea remedies and when to seek further help.
Speak to a pharmacist if:
- you have mild signs of dehydration
- you are unsure what to drink
- you need advice on oral rehydration sachets
- you want to know whether loperamide is suitable
- you take regular medicines and are not sure what to do
- you are older, pregnant, or have a long-term condition
For more about pharmacy advice, see When to See a Pharmacist Instead of a GP.
When to contact a GP or NHS 111
Contact a GP, out-of-hours service or NHS 111 if:
- you cannot keep fluids down
- you have signs of dehydration
- you are peeing much less than usual
- your diarrhoea lasts more than a week
- vomiting lasts more than 1 to 2 days or is repeated and persistent
- you have a fever that is high, persistent or worsening
- you have blood or mucus in your stool
- you have severe or worsening abdominal pain
- you have diarrhoea after recent travel
- you have recently taken antibiotics
- you are pregnant
- you are over 60 and symptoms are severe
- you have diabetes, kidney disease, heart disease or a weakened immune system
- you are worried or symptoms are not improving as expected
You can use NHS 111 online in England if you need urgent advice but it is not a 999 emergency.
If you need help arranging care, see How to Get a GP Appointment Quickly in the UK.
When to call 999 or go to A&E
Call 999 or seek emergency help if diarrhoea or vomiting comes with symptoms that suggest a serious emergency.
Call 999 if you or someone else has:
- confusion or severe drowsiness
- collapse or fainting that does not quickly recover
- severe dehydration
- blue, grey, pale or blotchy skin, lips or tongue
- severe chest pain
- severe breathing difficulty
- a stiff neck with severe headache or light sensitivity
- a non-blanching rash that does not fade when pressed
- vomit that contains blood or looks like coffee grounds
- severe, sudden or worsening abdominal pain
- signs of sepsis
Trust your judgement. If someone looks seriously unwell or is deteriorating quickly, seek urgent help.
Diarrhoea and vomiting with fever
A mild fever can happen with stomach bugs and food poisoning. It may come with chills, aches and tiredness. However, fever can also be a sign that the infection is more significant, especially if it is high, persistent or linked with severe pain, blood in stool, dehydration or recent travel.
Read more in Fever in Adults: What Temperature Means and When to Worry.
Diarrhoea after antibiotics
Antibiotics can upset the balance of bacteria in the gut and cause diarrhoea. Mild diarrhoea may settle after the course is finished, but some antibiotic-related diarrhoea can be more serious.
Seek medical advice if diarrhoea is severe, watery, persistent, contains blood, comes with fever or abdominal pain, or starts during or after antibiotics. Do not stop antibiotics early unless a clinician tells you to.
Diarrhoea and vomiting in pregnancy
Vomiting can happen in pregnancy, especially early pregnancy, but diarrhoea and vomiting can also be caused by infections or food poisoning. Pregnant women should be cautious about dehydration and foodborne infections.
Seek medical advice if you are pregnant and cannot keep fluids down, have signs of dehydration, have fever, severe abdominal pain, blood in stool, reduced movements later in pregnancy, or you are worried.
Diarrhoea and vomiting in people with diabetes
If you have diabetes, vomiting and diarrhoea can affect blood sugar control and increase the risk of dehydration. You may need to follow sick day rules, monitor blood sugar more often, and check ketones if advised.
Seek medical advice if you cannot keep fluids down, blood sugar is very high or very low, ketones are present, you are confused, drowsy, breathless, or you are unsure how to manage your medicines.
If blood sugar results are relevant to you, see HbA1c and Blood Sugar Results Explained.
Can diarrhoea and vomiting cause dizziness or fainting?
Yes. Fluid loss, low blood pressure, fever and not eating can make you feel dizzy or faint. This is more likely when standing up quickly or after repeated vomiting or watery diarrhoea.
Seek urgent advice if dizziness is severe, you faint, you have chest pain, palpitations, breathlessness, confusion, blood in stool or signs of dehydration.
Related guides include Dizziness: Common Causes and When to Worry and Fainting and Blackouts: Causes, Tests and When to Call 999.
Could it be something more serious?
Most diarrhoea and vomiting in adults is not serious, but some patterns need medical assessment.
Possible serious causes can include:
- appendicitis
- bowel obstruction
- severe food poisoning
- kidney infection
- sepsis
- inflammatory bowel disease flare
- pancreatitis
- gallbladder inflammation
- meningitis in rare cases, especially with fever, stiff neck and light sensitivity
Seek urgent medical advice if symptoms feel different from a usual stomach bug, pain is severe or localised, you are repeatedly vomiting, you cannot keep fluids down, or you are becoming more unwell.
What information should you give a doctor or pharmacist?
If you seek advice, it helps to describe the symptoms clearly.
Useful details include:
- when symptoms started
- how many times you have vomited
- how often you are passing diarrhoea
- whether there is blood or mucus
- whether you have fever
- whether you have abdominal pain and where it is
- whether you can keep fluids down
- how often you are peeing
- recent food, travel or contact with others who are unwell
- recent antibiotics or new medicines
- pregnancy or long-term health conditions
Frequently asked questions about diarrhoea and vomiting in adults
How long does diarrhoea and vomiting usually last?
Vomiting often improves within 1 to 2 days, while diarrhoea can last a few days longer. Many stomach bugs improve within a few days. Seek advice if symptoms are severe, worsening, or not improving as expected.
What is the best thing to drink when vomiting?
Try small, frequent sips of water or oral rehydration solution. If you vomit, wait a few minutes and then try again with tiny sips. Oral rehydration sachets from a pharmacy can be useful if you are dehydrated or losing a lot of fluid.
Should I stop eating if I have diarrhoea?
You do not need to force food if you feel sick, but you can eat small amounts when you feel able. Plain foods such as toast, rice, bananas, soup, crackers or potatoes may be easier at first. Fluids are more important than food in the early stage.
Can I take loperamide for diarrhoea?
Loperamide may help some adults with short-term diarrhoea, but it is not suitable for everyone. Avoid it and seek advice if you have blood in your stool, high fever, severe abdominal pain, suspected severe food poisoning, inflammatory bowel disease, or diarrhoea after antibiotics.
When should I worry about dehydration?
Seek medical advice if you are extremely thirsty, dizzy, confused, unusually tired, peeing much less than usual, have very dark urine, a fast heartbeat, or cannot keep fluids down. Severe dehydration needs urgent help.
Can diarrhoea and vomiting be caused by food poisoning?
Yes. Food poisoning can cause diarrhoea, vomiting, nausea, stomach cramps and fever. Symptoms may start within hours or days of eating contaminated food. Most cases improve at home, but severe symptoms, dehydration, blood in stool or pregnancy need medical advice.
How long should I stay off work?
Stay off work while you are actively vomiting or having diarrhoea. The NHS advises staying away from work or school until you have not been sick or had diarrhoea for at least 2 days, because stomach bugs can spread easily.
Is diarrhoea with fever serious?
It can be mild with a stomach bug, but fever with diarrhoea may need advice if the fever is high, persistent, or comes with blood in stool, severe abdominal pain, dehydration, recent travel, pregnancy, older age or a weakened immune system.
What if I have blood in my stool?
Blood in the stool should not be ignored. It can happen with infections, piles, inflammatory bowel disease and other causes. Seek medical advice urgently if there is a lot of blood, black stool, severe pain, dizziness, fever or you feel very unwell.
Can stress cause diarrhoea and vomiting?
Stress and anxiety can affect the gut and may cause nausea, looser stools or stomach discomfort. However, sudden diarrhoea and vomiting is more often caused by infection, food poisoning or another physical trigger. Seek advice if symptoms are severe, persistent or unusual for you.
Final thoughts
Diarrhoea and vomiting in adults are usually caused by a stomach bug or food poisoning and often improve within a few days. The most important thing is to drink fluids regularly and watch for dehydration.
Stay home while symptoms are active, wash hands carefully and avoid preparing food for others. A pharmacist can help with oral rehydration and suitable over-the-counter options. Contact a GP or NHS 111 if symptoms are severe, persistent, linked with fever, travel, pregnancy, dehydration, blood in stool or significant abdominal pain. Call 999 if there are emergency symptoms such as confusion, collapse, severe dehydration, severe pain, blood in vomit, a non-blanching rash or breathing difficulty.
For official guidance, see the NHS pages on diarrhoea and vomiting, dehydration and food poisoning.
This article is for general information only and should not replace medical advice. If you are worried about your symptoms or someone else’s, contact NHS 111, your GP, or call 999 in an emergency.
