E. coli infection: symptoms, how long it lasts, treatment and when to get help

NHS inform says Escherichia coli (E. coli) are bacteria found in the environment, food, and the intestines of animals and people. Most types are harmless and are an important part of a healthy digestive tract. Some can make you unwell.

It divides them into two groups: those that can produce Shiga toxin, known as Shiga toxin-producing E. coli (STEC), which includes E. coli O157, and those that cannot. STEC are known to cause more severe illness.

UKHSA says the most common type of STEC in the UK is O157.

E. coli is also a common cause of urinary tract infections. NICE says E. coli is the most commonly identified cause, found in up to 77% of cases of lower UTI in women. This page focuses on the gut infection; see the UTI page for bladder infections.

UKHSA says people infected with STEC can have a combination of diarrhoea (about 50% of cases have bloody diarrhoea), stomach cramps and fever. Some people have mild diarrhoea, or no symptoms at all, which is called asymptomatic carriage.

NHS inform lists diarrhoea, stomach pain, vomiting, fever and bloody diarrhoea. It says STEC can cause severe stomach pain, bloody diarrhoea and kidney failure.

NHS inform says it usually takes 2 to 4 days from being infected to developing symptoms, though in some cases symptoms can start anywhere between 1 and 14 days afterwards.

Most people get better within 5 to 7 days but sometimes symptoms can last up to 2 weeks. UKHSA says it often clears within a week, and that symptoms can last up to 2 weeks in cases without complications.

Yes. UKHSA says STEC are very infectious because very few bacteria (possibly fewer than 100) are needed to cause illness. It spreads easily within families and in nurseries, primary schools, nursing homes and hospitals.

NHS inform says most people are no longer infectious after about a week, but some people, particularly children, may carry STEC for several months after getting better and could still pass it on.

NHS inform says anyone who has had a STEC infection should stay away from work or school until they have been completely free of symptoms for 48 hours. UKHSA says people who have been ill should not prepare food for others for at least 48 hours after they have recovered.

UKHSA says there is no specific treatment for STEC infection. The illness is usually self-limiting and will get better without treatment. It is important to drink plenty of fluids, as diarrhoea can lead to dehydration.

UKHSA says antibiotics are not recommended and are likely to increase the risk of complications such as haemolytic uraemic syndrome (HUS). NHS inform adds that anti-diarrhoeal drugs like loperamide are also not recommended in most cases, because they may prolong exposure to the toxin.

NHS inform says this can nevertheless be a serious infection requiring admission to hospital. The NHS diarrhoea and vomiting page says to avoid fruit juice and fizzy drinks, and not to give children under 12 medicine to stop diarrhoea.

UKHSA says cattle are the most important reservoir of STEC O157 in the UK. People can become infected through:

• Eating contaminated food, for example undercooked minced beef, unpasteurised milk or dairy products, and contaminated fresh produce.

• Contact with infected animals, directly or through animal faeces, for example at farms, petting farms and campsites.

• Contact with other people who have the illness, through inadequate hand hygiene.

• Drinking water from inadequately treated supplies.

• Swimming or playing in contaminated water such as ponds or streams.

NHS inform says a small number of people, mainly children, with STEC go on to develop HUS, a serious life-threatening condition. Symptoms include peeing less, pee that is pink or brown, tiredness, swelling and bruising. It says this can sometimes lead to kidney failure and death, although this is rare, and that the risk is highest in children under 5.

UKHSA clinical guidance says it is thought that up to 10% of cases develop HUS after an initial period of gastroenteritis or bloody colitis, most commonly in young children or the elderly. It says a small proportion of adults may develop a similar condition called thrombotic thrombocytopaenic purpura (TTP).

NHS inform lists pregnant women among the people with a weakened immune system who are particularly vulnerable and may be at increased risk from unpasteurised dairy products, which may contain STEC.

For urinary infection, the NHS says to ask for an urgent GP appointment or get help from NHS 111 if you think you may have a UTI and you are pregnant.

If you are pregnant and have bloody diarrhoea or are unwell, contact your GP practice, midwife or NHS 111 promptly.

NHS inform says to contact your GP practice urgently if you or your child has bloody diarrhoea, and to phone 111 if your GP practice is closed.

It says to contact your GP practice if you or your child has diarrhoea and any of the following:

• It is particularly frequent or severe.

• It lasts for more than 7 days.

• Vomiting lasts for more than 2 days, or you keep being sick and cannot keep fluids down.

• You have a severe or continuous stomach ache.

• You have lost weight, or pass a large amount of very watery diarrhoea.

• You have signs of dehydration, like dark, smelly pee or peeing less than usual.

UKHSA advises cooking all minced meat products thoroughly until the colour is the same all the way through and no blood runs from them. Wash salad vegetables, do not use a utensil on raw meat and then on other food before washing it, store raw meat below cooked food, and boil drinking water if unsure of its source.

Children and elderly people, who are particularly susceptible, should avoid unpasteurised dairy products.

To stop spread at home, NHS inform advises washing hands thoroughly with soap and water after the toilet, changing nappies, contact with animals and before preparing food. It says to wash soiled clothing and bedding separately on a hot wash, and to clean toilet seats, flush handles, taps and surfaces at least daily.

STEC is usually diagnosed by a stool sample, and UKHSA says cases are reportable to local health protection teams under the Health Protection (Notification) Regulations 2010. This is handled by the NHS and public health system.

Private stool testing is available, but any positive result still needs to go through your GP or the local health protection team so that contacts and exclusion advice are handled properly.