What is HUS (haemolytic uraemic syndrome)?
Haemolytic uraemic syndrome (HUS) is a rare condition that affects the kidneys. This condition is the most common cause of acute kidney injury in children. Common features of HUS include:
- Anaemia, caused by the loss of red blood cells meaning there are fewer in number.
- A low platelet count. Platelets are involved with blood clotting, and a shortage can cause you to bleed easily This can cause small red or purple spots under the skin.
- Kidney failure or damage. This is caused by damage to tiny blood vessels within your kidney’s filtering system which become blocked by blood clots.
- Severe HUS can also affect the brain, gut, heart, liver and pancreas.
Causes of haemolytic uraemic syndrome (HUS)
HUS has two main causes, known medically as STEC-HUS and atypical HUS.
STEC-HUS, also known as typical HUS, is the most common and usually happens after a tummy infection, caused by bacteria that produce a toxin called Shiga-toxin (also known as verotoxin). In most cases, Shiga-toxin is produced by E.coli O157 bacteria, hence the name Shiga-toxin producing E.coli (STEC). This type of E. coli can be found in:
- The gut of healthy cattle, goats and sheep. Eating under cooked beef, unpasteurized milk, or other contaminated food or drink can cause infection with E.coli O157.
- Contaminated water. This includes drinking water and recreational water.
- People infected with E.coli O157. This infection can spread from person to person through contaminated faeces (poo).
Very young children (under 5 years old) are the most likely to develop HUS.
HUS typically develops a few days after a bout of bloody diarrhoea.
Only about 1 in 20 people with E.coli O157 gastroenteritis get HUS as a complication.
Atypical Haemolytic Uraemic Syndrome (aHUS) is caused by changes in the complement system – a part of our immune system which helps destroy bacteria and viruses.
Sometimes HUS may be associated with other medical conditions which include:
- Infections with other types of bacteria
- Some viruses, such as HIV
- Certain medications, such as some immunosuppressants
- Cancer
- Pregnancy
Haemolytic uraemic syndrome (HUS) symptoms
Initial symptoms in children with STEC-HUS include:
- Diarrhoea (runny poo) which can contain blood after a few days
- Stomach pain
- Being sick
- High temperature
Initial symptoms of atypical HUS include:
- Extreme tiredness
- Pale skin
For both causes of HUS, when they progress, they can cause kidney and anaemia related symptoms including:
- Decreased urine production
- Too much fluid build-up in the body, which can cause swelling
- Fainting
- Extreme tiredness
- Pale skin
Haemolytic uraemic syndrome (HUS) diagnosis
If your doctor suspects you may have HUS based on your history and symptoms, further tests include:
- Blood test. This allows your doctor to look at your red blood cells and platelets, how well your blood is clotting, and markers of kidney function and other markers associated with HUS.
- Urine test to look at kidney function
- Liver function tests
- A stool (poo) sample to look for E. coli O157
- If aHUS is suspected specialist tests may be needed, such as genetic testing
Additional tests may also be needed to rule out other conditions that can have similar symptoms to HUS.
Haemolytic uraemic syndrome (HUS) treatment
Treatments depend on how severe HUS is and the cause but may include:
- Dialysis, which can be temporary
- Blood transfusions, where blood from another person (called a donor) is given into a vein in your arm
- Medications to reduce high blood pressure
- For aHUS treatments can include
- Eculizumab, a drug that reduces the activity of the complement system.
- Plasma exchange, a procedure that removes plasma (a clear, straw-coloured liquid) from the blood and replaces it with new plasma fluid.
If your HUS has been caused by an E.coli O157 infection, your local health protection team will be informed, and extra precautions may be taken to prevent any spread of infection.
If another cause of HUS is suspected, then other specific treatments might help.
Possible outcomes
The outlook for patients with STEC-HUS is generally good and for most patients who usually recover with little evidence of kidney damage. However, HUS is a serious disease, and some people can have severely damaged kidneys or die as a result of HUS.
After recovery, you may be left with mild permanent kidney damage, but sometimes it can be more severe. In the most severe cases, other organs may be damaged too.
The outlook for patients with atypical HUS used to be poor, with many patients needing long-term dialysis with a high risk of the disease returning if transplanted. New treatments have become available that have improved outcomes in recent years.
The outlook for patients with other causes of HUS is unclear.
Useful resources about haemolytic uraemic syndrome (HUS)
If you have been diagnosed with HUS and have any questions or don’t hesitate to speak to your kidney specialist or your nurse specialist at the kidney unit. The National aHUS Service – a team of aHUS experts based at the Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University – can also provide further information about aHUS.
Reviewed Feb 2026
Professor Richard Coward
Researcher spotlight
New results from researchers at the University of Bristol, led by Professor Richard Coward, have demonstrated how infection with a toxin-producing bacteria can lead to the condition haemolytic uraemic syndrome (HUS), a leading cause of kidney failure in children.
The results suggest that early treatment with the drug eculizumab might prevent life-threatening kidney damage and death in some children.
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