Infections
Infections are not usually serious. But infections that last a long time or keep coming back can be a sign of leukaemia or other types of blood cancer. Here, we cover some of the warning signs and when to seek help.
Summary
- Infections are extremely common. Most of the time, they’re not serious.
- But frequent or long-lasting infections can be a symptom of leukaemia or other types of blood cancer.
- If you keep getting infections that last a long time or keep coming back, make an appointment with your GP and ask for a blood test.
About infections
Infections are extremely common. Most adults get two to four respiratory infections every year. And it’s not unusual for children to get as many as ten. Infections are an annoying part of life but they’re not usually serious.
Infections can be caused by viruses, bacteria or fungi and can affect any part of the body. Common infections include coughs, colds, flu, urine infections, ear or throat infections and food poisoning. These are generally mild and get better within a few weeks. Sometimes on their own, or sometimes with simple treatments from a GP or pharmacist.
But infections could be a sign of leukaemia or other types of blood cancer if:
- You get a lot of them
- They last a long time
- They keep coming back
Infections can also be a side effect of treatment for blood cancer. We have separate information on managing your infection risk for people who already have a diagnosis.
Like all symptoms of leukaemia, repeated or long-lasting infections can be caused by many things. Getting them does not mean you definitely have leukaemia. But if you’re worried about your symptoms, it’s a good idea to see your GP.
Signs and symptoms of infections
Signs and symptoms can vary depending on the germ causing the infection, the site of infection and how severe it is.
Common signs and symptoms of infections include:
- A high temperature (37.5°C to 38°C or higher)
- A low temperature (below 35°C)
- Shivering, chills and sweating
- Feeling generally unwell, dizzy, confused or disorientated
- Sore throat or sore mouth
- Sneezing, blocked or runny nose, earache
- Cough or shortness of breath
- Skin sores or rash (this can be harder to see on brown or black skin)
- Pus or redness around cuts or injuries (this can be harder to see on brown or black skin)
- Tingling of the skin
- Diarrhoea or vomiting (being sick)
- Burning or stinging when you pee, or needing to pee more often than usual
- Discharge from your genitals or itching around your genitals
- Unusual or new neck stiffness, along with finding bright lights uncomfortable
- New or worsening pain
Why do people with blood cancer get infections?
If you have blood cancer, your immune system may not work properly. This is because cancer cells can fill up your bone marrow and stop it making enough healthy blood cells. This includes white blood cells, which usually help your body fight infections.
There are several types of white blood cell.
- Some of them kill germs directly.
- Some of them make antibodies. These stick to germs and help other immune cells find them and kill them.
- Some of them send signals to tell other immune cells to come and help fight the infection.
If you have blood cancer, you might have high levels of some white blood cells and low levels of others. But the white blood cells that are high are often abnormal and don’t work properly. They cannot help your body fight infections.
Neutrophils
- Neutrophils are the most common type of white blood cell in your body. Around 7 in every 10 white blood cells are neutrophils.
- Your bone marrow usually makes around 100 billion neutrophils every day.
- Neutrophils ‘eat’ germs that have invaded your body and release proteins to kill them. They are an important first defence against infections.
- If you have blood cancer, or you are having treatment for blood cancer, you may have a low neutrophil count. This is called neutropenia.
- The lower your neutrophil count, the higher the chance of getting serious infections.
- We have separate information on managing your risk of infections for people with a lowered immune system. This includes people with neutropenia.
What else can cause infections?
Frequent or long-lasting infections can be caused by lots of things. Most people who have them do not have blood cancer.
Infections are extremely common. Most of the time, they’re not due to anything serious. Sometimes, though, repeated, unusual or recurrent infections can be a sign of an underlying condition or cause. These include:
- Some medicines. This includes steroids, cancer treatments, medicines used to treat autoimmune conditions, anti-rejection drugs after a transplant, and some allergy medicines. These can all lower your immune system.
- Some infections. It might seem strange, but some infections can lower your immunity and make you prone to other infections. Examples include measles, TB, COVID and HIV.
- Genetic conditions. This includes conditions that affect your immune system, and some other genetic conditions, like cystic fibrosis or Down syndrome.
- Diabetes.
- Kidney disease.
- Malnutrition.
- Low vitamin or mineral levels
- Having had your spleen or thymus removed. These organs are both important parts of your immune system.
- Other blood cancers.
When to seek help
- If you think you or someone you care for might have a serious infection, call 999 or go to A&E straight away. If you're not sure if the symptoms are serious, visit NHS 111 online or call 111 for advice.
- If you are having treatment for blood cancer and you think you might have an infection, contact your haematology team or GP urgently.
- If you feel very unwell or you’ve had a high temperature for 3 days or more, visit NHS 111 online, call 111 or make an urgent appointment with your GP.
If you keep getting infections that are more serious than usual, last a long time or keep coming back, make an appointment with your GP and ask for a blood test.
Nearly 4 in 10 people with leukaemia wait 3 months or more before contacting a GP about their symptoms.
Some signs that you should contact your GP include infections that:
- Happen frequently.
- Keep coming back.
- Last a long time.
- Are accompanied by other symptoms of leukaemia.
- Are more severe than in other people.
- Do not respond to usual treatments.
- Are caused by unusual germs. Your GP might tell you this.
If you have frequent or long-lasting infections and your GP can’t identify a cause, they should consider an urgent blood test. If they don’t offer you a blood test, ask for one.
If you are struggling to get help
Nearly 3 in 10 people with leukaemia have to speak to their GP three or more times before getting a diagnosis.
There may be many possible explanations for your symptoms for a GP to consider.
If you have to go back to your GP three or more times about the same symptom, remind them about Jess’ rule. This encourages GPs to ‘reflect, review and rethink’, particularly if:
- You still have the symptoms
- They have got worse
- They are unexplained
Take a look at our Spot Leukaemia campaign to find out what we’re doing to help the public and GPs spot the signs of leukaemia sooner.
Sources
Sources we used to develop this information
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Page last reviewed: 10 September 2026
Updated September 2026
Next review due: 30 September 2029
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