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Infection risk in CLL and how to reduce it | CION Cancer Clinics
CLL raises your infection risk even before treatment, because the CLL cells do not fight infection and antibody levels often fall. Treatment can lower defences further. A fever with CLL needs same-day hospital care. This page explains why infections happen, which ones are common, the daily habits and vaccines that lower the risk, and what it cannot tell you about your own situation. At CION Cancer Clinics, every leukaemia, MDS and MPN case is reviewed by our haematologist and discussed at a tumour board before a plan is agreed.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- Why does CLL make infections more likely?
- Which infections are most common in CLL?
- How can you reduce your infection risk day to day?
- Which report words tell you about infection risk?
- What do families believe about CLL and infection that is not true?
- Who needs extra protection, and what can this page not tell you?
- Common questions about infections in CLL
!
Fever with CLL cannot wait until morning
If you have CLL and develop a temperature of thirty-eight degrees or higher, shivering, breathlessness, confusion or feel suddenly very unwell, go to the nearest emergency department now or call 108. Say that you have CLL and name any treatment you are on. Do not take paracetamol and wait to see if it settles.
The short answer
Why does CLL make infections more likely?
CLL weakens the immune system even before any treatment starts. Infections are one of the most common serious problems in CLL, so reducing that risk is part of looking after the disease, not an extra.
The CLL cells do not fight infection
CLL is a cancer of lymphocytes, a type of white blood cell. The CLL cells look like lymphocytes but do not work properly. As they build up, they crowd out the healthy immune cells that would normally deal with bacteria and viruses.
Antibody levels often fall
Many people with CLL make fewer antibodies, also called immunoglobulins. Antibodies are the proteins that remember past infections and vaccines. When they are low, chest and sinus infections come back more often and take longer to clear.
Treatment adds to the risk
Most CLL treatments lower the immune defences further for a while. Some drop the neutrophils, the white cells that fight bacteria. Others deplete the B cells that make antibodies. Older age, diabetes, lung disease and kidney disease add to the risk as well.
Why infections hit harder
With CLL, an ordinary cough can turn into pneumonia within a day or two, and the usual warning signs can be milder than you expect. Some people on treatment feel only tired or slightly off before becoming very unwell. This is why haematologists ask you to act early on a fever instead of waiting to see how it goes.
Not sure whether this applies to you?
Ask an oncologistWhat to watch for
Which infections are most common in CLL?
These are the patterns haematologists see most. Any of them can become serious faster than in someone without CLL.
Chest infections
Bronchitis and pneumonia are the most frequent. Watch for a cough with coloured phlegm, fever, chest pain or breathlessness.
Shingles and cold sores
Viruses that sleep in the body can wake up. Shingles starts as pain or tingling on one side, followed by a band of blisters. Early antiviral treatment matters.
Sinus, ear and urine infections
Repeated sinus or ear infections are often an early sign of low antibody levels.
Mention it if you notice
- Burning when passing urine
- Facial pain with blocked nose that lasts
- Ear pain or discharge
Unusual infections
On some treatments, rarer infections such as fungal chest infections or a pneumonia called PJP can occur. Your team may give preventive medicines for these.
What you can do
How can you reduce your infection risk day to day?
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Keep your vaccines up to date
Flu, pneumonia and COVID-19 vaccines are usually advised. Live vaccines are generally avoided in CLL. Ask your haematologist before any vaccine, including travel vaccines.
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Wash hands and handle food carefully
Wash hands before eating and after travel or toilet use. Eat freshly cooked food, drink boiled or filtered water, and avoid street food and unpasteurised milk, especially during treatment. Wash fruit and vegetables well, and peel them where you can.
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Keep a distance from people who are ill
Ask visitors with a cold, fever or chickenpox to stay away. In crowds or on buses during flu season, a mask helps. Tell your team if you have been near someone with chickenpox or shingles.
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Look after your mouth and skin
See a dentist regularly, clean small cuts at once and keep them covered. Tell the team before any dental work.
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Take preventive medicines exactly as prescribed
Some people are given antiviral or antibiotic tablets to prevent infection. Do not stop them because you feel well. Ask first.
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On your report
Which report words tell you about infection risk?
- Neutrophils
- The white cells that fight bacteria. A low count raises the chance of a sudden, serious infection.
- Lymphocytes
- In CLL this count is often high, but most of the cells are CLL cells. A high number does not mean strong immunity.
- IgG, IgA, IgM
- The main antibody types. Low IgG is the one most linked to repeated infections.
- CRP
- A blood marker that rises with inflammation or infection. It helps doctors judge how unwell you are.
Commonly believed
What do families believe about CLL and infection that is not true?
"His lymphocyte count is so high, his immunity must be strong."
The high count is mostly CLL cells, which do not protect against infection. Immunity is often weaker, not stronger. The number that tells you more about protection is the neutrophil count, along with your antibody levels.
"We are on watch and wait, so infection is not a worry yet."
The immune system is already affected in untreated CLL. Vaccines, hygiene and early attention to fever matter from the day of diagnosis. This is also the ideal window for vaccines, before any treatment lowers the response further.
"We will start the leftover antibiotics at home and see."
Leftover or chemist-bought antibiotics may be the wrong ones and delay proper care. With CLL, a fever needs assessment the same day.
"Vaccines are wasted on people with CLL."
They may work less well than in healthy people, but they still give useful protection. Timing matters, so ask your haematologist when to have them around treatment.
Being straight with you
Who needs extra protection, and what can this page not tell you?
Some people need more than everyday care. If you keep getting chest or sinus infections despite vaccines, your haematologist may check your antibody levels and discuss immunoglobulin replacement, a drip of donated antibodies. It does not suit everyone, and it is usually kept for people with low levels and repeated serious infections.
What this page cannot tell you
It cannot tell you your own risk, which preventive medicines you need, or whether a symptom today is serious. Your counts, your treatment and your other illnesses change the answer. A normal blood report last month does not mean an infection this week is minor, and a low result does not mean infection is certain.
What to ask at your next visit
Ask which vaccines you are due, whether you need preventive tablets, what temperature should send you to hospital, and whom to call at night. Write the answers down and keep them where the family can find them. If you live in a district far from Hyderabad, ask which nearby hospital you should go to in an emergency, and carry a short note of your diagnosis and treatment when you travel.
Questions we are asked
Common questions about infections in CLL
Is every fever an emergency when you have CLL?
A fever needs to be taken seriously, especially during treatment or if your neutrophils are low. Go to the emergency department or call your team the same day. Infections can move quickly in CLL, and early antibiotics make a real difference.
Can I travel or attend family functions?
Usually yes, with some care. Avoid crowded, closed spaces when counts are low, wash hands often and eat freshly cooked food. Ask your team before long trips or visits to areas with outbreaks, and carry your reports and medicine list.
Should I get the shingles vaccine?
The non-live shingles vaccine is often advised for people with CLL. The older live vaccine is generally avoided. Ask your haematologist which one is available to you and when it fits most sensibly around your treatment.
Can grandchildren who had live vaccines visit?
In most cases, yes. Children should get their routine vaccines, which also protects you. A few live vaccines need extra hygiene precautions afterwards. Ask your team about the specific vaccine, and keep children with chickenpox away.
Do I need to wear a mask all the time?
Not usually. A mask is most useful in crowded indoor places, hospital waiting areas and during flu or COVID-19 waves, and when counts are low. Hand washing and avoiding sick contacts matter just as much.
Why was I given tablets to prevent infection?
Some CLL treatments raise the risk of specific infections such as shingles or PJP pneumonia. Preventive antiviral or antibiotic tablets lower that risk. Take them exactly as prescribed and ask before stopping, even if you feel completely well.
Can diet or supplements boost immunity in CLL?
A balanced diet helps your general health, but no food or supplement has been shown to fix the immune weakness of CLL. Some herbal products interact with CLL medicines. Show your team anything you plan to take.
What should the family do if I become confused with a fever?
Confusion with a fever can be a sign of a serious infection. The family should take you to the nearest emergency department at once or call 108, and tell the staff about your CLL and treatment. Keep a copy of your latest reports ready.
Your Haematologist
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- NHS — Chronic lymphocytic leukaemia
- Cancer Research UK — Chronic lymphocytic leukaemia (CLL)
- Leukaemia & Lymphoma Society — Chronic lymphocytic leukemia
- Blood Cancer UK — Chronic lymphocytic leukaemia (CLL)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Talk to us
Worried about repeated infections with CLL?
Share your reports with us. CION's haematology team will review your risk and talk through prevention. One helpline serves every CION centre.