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Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 5 minutes read

Gastroenteritis is a gut infection that causes abdominal pain, diarrhoea and nausea or vomiting. You might also feel feverish and will almost certainly be off your food. It's very common, with about 20 per cent of people in the UK being affected by it every year although for most people this is mild and self-limiting and does not require medical attention.

Any number of bugs can cause it, but viruses are the most common cause in the UK – rotavirus is a common culprit and outbreaks can occur in schools and workplaces. Bacteria may cause gastroenteritis from contaminated food or water, such as meat that hasn’t been cooked through, for example at barbecues, or rice or salad that has sat out, such as a buffet on a warm day, or drinking from a stream or pond.

Travel to exotic locations or ones without good sanitation may bring you into contact with parasites or bacteria, and these may be responsible for your gastroenteritis.

Most cases will resolve without treatment and by drinking plenty of fluids in order to prevent dehydration. The majority of gastroenteritis cases improve significantly within 72 hours, however sometimes may continue for up to 5-10 days.

The infection – whether  viral or bacterial – irritates the lining of the stomach and gut making the bowel muscles tighten, which in turn triggers vomiting and/or diarrhoea. Depending on the type of bug involved and its severity, symptoms can occur from an hour to several days after getting infected.

What are the symptoms?

The main symptom is usually watery diarrhoea, and you may also feel sick and start vomiting. In some cases of gastroenteritis there may be blood or mucus in the stools. Cramping abdominal pains are usual, and these may come and go, typically being worse before a bowel movement and easing afterwards. There may also be a high temperature, tiredness and muscle aches and pains.

How is it diagnosed?

Most people with mild gastroenteritis recognise their symptoms and do not need any medical attention. Tests are not usually needed although if diarrhoea persists for a number of days then a stool (faeces) sample may be tested to try to identify the cause of the infection. Diagnosis is mostly by the symptoms alone however.

Doctor’s advice

Is it contagious?

Gastroenteritis is very contagious and you should keep yourself to yourself if you are experiencing vomiting and diarrhoea.

Surfaces can get contaminated with virus particles that can be passed on. You should not be going to work or public places, and should keep to your own bathroom if your home set-up allows it. Avoiding preparing food or serving food to others, and make sure you maintain thorough and regular hand washing.

Anti-sickness or anti-diarrhoeal tablets are not usually required, unless the symptoms are severe. Antibiotics are not usually prescribed unless there is a bacterial cause identified that will respond to antibiotics, which usually means waiting for a stool sample result to come back.

If you need to take anti-diarrhoea medication to stop the diarrhoea for a short amount of time it is best to first discuss it with your pharmacist first, or with your doctor via a telephone appointment.

Keep drinking but don’t worry if you don’t feel like eating for a few days – listen to your gut. When hungry, eat plain and easily digestible foods until you feel better to give your gut a rest and gently add bulk to the stool, such as rice, mashed potato, or soft bread dipped in a well-cooked soup.

Bananas add soft bulk and fibre, as well as providing some energy and a good source of potassium. Avoid dairy for a few weeks, as this can exacerbate your gut lining while it tries to repair.

Healthwords pharmacists' top tips

The use of anti-diarrhoea capsules is usually best avoided unless you are travelling or unable to access a toilet nearby, or if you are going to the toilet every 30 minutes or so and are at risk of severe dehydration due to more loss of fluid than can be topped up by drinking water. This is because reducing gut motion may only delay the body's natural process to flush the toxins out of the body quickly.

Drinking water is the best thing to top up fluid levels, but you also need to top up electrolytes (salts) lost through vomiting and diarrhoea. The use of oral rehydration salt drinks can help to replenish electrolyte and fluid levels and help prevent dehydration, helping you to a quicker recovery.

Other products that may help with symptoms include Enterosgel sachets, which bind to and expel toxins in the gut and also help settle the stomach. Pepto-Bismol can help calm the gut by neutralising acidity in the gut, calming nausea, diarrhoea and belching.

For fever, you can take paracetamol if necessary.

Am I fit for work?

You are not fit for work if you have gastroenteritis and should not return to a work setting until 48 hours after your symptoms stop (unless you work from home)- this is to minimise the risk of passing it onto anyone else.

When should I see my doctor?

If your symptoms continue or do not start to improve after five to seven days, if you have blood in the diarrhoea, if you think you are at risk of dehydration, or you have travelled abroad recently, you should let your doctor know and then arrange for a stool sample to be sent off for further investigation.

You should call your doctor if you are over 65 years old, pregnant or have an underlying health condition. If your symptoms are severe, for example, you have a fever, are feeling dizzy or faint, or are struggling to maintain oral fluids, it would be best to discuss with your doctor. A small number of cases of gastroenteritis can be serious and may need hospital treatment because of severe dehydration.

The doctor will ask you about your medical history, your recent symptoms and any relevant information that might suggest what the cause of it was, such as any recent foreign travel, any recent stay in hospital or use of antibiotics, or any risk of having eaten undercooked meat.

If you are seeing them in person they will check your temperature, heart rate and blood pressure, and they may examine your tummy. They may ask for a stool sample, especially if diarrhoea has continued for a long time.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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