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CION Cancer Clinics
Infection during the low-count weeks after a stem cell transplant | CION Cancer Clinics
Infection is the main danger in the weeks after a transplant, because the body has almost no infection-fighting white cells until the new marrow starts working. A fever may be the only early sign, so it is always treated as urgent. This page explains where infections come from, what the ward team does when a fever appears, and what you as family can do to help. At CION Cancer Clinics, our haematology team assesses whether a transplant or CAR-T fits your situation and coordinates care with qualified centres.
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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 is infection the biggest risk in the first weeks after transplant?
- Where do infections come from when counts are this low?
- What does the team do the moment a fever appears?
- What do families often misunderstand about infection risk?
- How can you help lower the risk, and what can this page not tell you?
- What do the words on the report mean?
- Common questions about infection after transplant
The short answer
Why is infection the biggest risk in the first weeks after transplant?
After conditioning, the body has almost no neutrophils, the white cells that fight bacteria and fungi first. Until the new marrow starts making them, even germs that normally live harmlessly on your skin or in your gut can cause a serious infection within hours.
What the neutropenic phase means
Neutropenic simply means the neutrophil count is very low. On a transplant ward it describes the stretch between conditioning and engraftment, when the new stem cells begin to produce white cells. Almost everyone having a transplant goes through it. It is expected, and the whole ward is built around it.
Why a fever is treated so differently here
With normal counts, a fever is the body fighting a germ well. With almost no neutrophils, the usual warning signs such as pus, swelling or a cough may barely appear. Fever is often the only early sign. That is why the team treats a new fever as urgent, even when the person looks fine.
Most people in this phase get at least one fever. It does not mean the transplant is failing.
!
A fever cannot wait
On the ward, if the person feels hot, starts shivering, becomes confused, breathless or very drowsy, press the call bell now. After discharge, a temperature of 38 degrees Celsius or above, or shivering without a thermometer reading, means calling the transplant unit at once or going to the nearest emergency department. Call 108 if the person is too unwell to travel. Say they have had a recent stem cell transplant. Do not give paracetamol first and wait to see.
Not sure whether this applies to you?
Ask an oncologistWhere germs come from
Where do infections come from when counts are this low?
Most come from inside the body, not from visitors. That is why the ward focuses on the gut, skin, mouth and line as much as on the door.
Your own gut
Conditioning damages the gut lining. Bacteria that normally stay inside the bowel can slip into the blood through the broken lining.
The central line
The thin tube in the chest or neck used for drips and blood tests is a direct route into the bloodstream. Nurses handle it with strict clean technique every time.
Tell the nurse about
- Redness or pain where it enters
- Shivering during a flush
Fungi
Moulds in dust, soil, building work and some foods can reach the lungs. This is one reason rooms have filtered air and flowers and plants are not allowed.
Old viruses waking up
Viruses you caught years ago, such as the cold sore or chickenpox virus, can become active again. Blood tests for some viruses are done regularly for this reason.
On the ward
What does the team do the moment a fever appears?
Check and examine
Temperature, pulse, blood pressure and breathing are checked. The doctor looks at the mouth, skin, chest, line site and back passage area for any sign of where the infection is.
Blood cultures
Blood is drawn from the line and often from an arm vein, to grow any germ in the laboratory. Urine and other samples may be sent too.
Antibiotics straight away
Strong antibiotics through the drip start without waiting for the results. Waiting for a germ to be named would lose precious time.
Review and adjust
If the fever continues, the team may add antifungal or antiviral medicines, or arrange a chest scan. The plan changes as culture results come back.
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Commonly believed
What do families often misunderstand about infection risk?
"If we keep the room spotless, there will be no infection."
Cleanliness lowers the risk a great deal, but many infections start from germs already inside the body. A fever despite perfect care is not the family's fault, and not the nurses' either.
"The antibiotics were started, so it must be serious."
Starting antibiotics at the first fever is routine in this phase. It is a safety step, not a sign that something has gone badly wrong. Often no germ is ever found.
"A mask is enough, so a visitor with a cold can come in."
Masks help but do not stop everything. Anyone with a cough, cold, fever, loose motions or a rash should stay away until they are well, even if they are the closest family member.
"Once he is home, the danger is over."
Counts recover in stages and the immune system takes months to rebuild. Fever after discharge still needs the same urgent response. The unit will give you written rules for home.
What families can do
How can you help lower the risk, and what can this page not tell you?
Wash your hands, or use the hand rub, every single time you enter the room and before touching the patient. Follow the unit's rules on masks, gowns, food and what you may bring in, even when they seem strict.
Small habits that matter
Keep the attendant healthy and rested, because a sick attendant cannot go in. Do not bring outside food, fruit or flowers unless the unit has said yes. Help the patient keep up the mouth rinses and a daily wash. Remind them to report any new pain, cough, burning on passing urine or soreness around the line.
Medicines to prevent infection
Most units give preventive antibiotic, antifungal and antiviral medicines during this phase. The choice depends on the type of transplant and the centre. Never stop, skip or change any of them on your own.
What this page cannot tell you
It cannot tell you how likely an infection is for your family member, or how a particular fever will go. That depends on the transplant type, earlier infections and how quickly counts recover. Ask the treating team.
On the chart
What do the words on the report mean?
- ANC
- Absolute neutrophil count. The number of infection-fighting neutrophils in the blood. Reference ranges differ between laboratories, and one result is read alongside symptoms and repeat tests.
- Neutropenic fever
- A fever while the neutrophil count is very low. It is treated as an emergency even if the person feels well.
- Blood culture
- A blood sample kept warm in the laboratory to see whether any germ grows. Results take a day or more.
- Engraftment
- When the new stem cells start making white cells, and the infection risk begins to fall.
Questions we are asked
Common questions about infection after transplant
How long does the high-risk phase last?
It usually lasts until engraftment, when the new marrow starts producing neutrophils. The length varies with the type of transplant and the source of the stem cells. Even after counts recover, the immune system stays weaker for months, so some precautions continue after you go home.
Can I visit if I have a mild cold?
No. Stay away until you are fully well and send another attendant in your place. A cold that is a nuisance for you can become a serious chest infection for someone with no white cells. Tell the nurse in charge, who can advise when it is safe to return.
Why does he need so many blood tests?
Counts, kidney and liver tests guide the antibiotics and fluids, and some virus tests pick up a problem before symptoms appear. Most samples come from the central line, so there are fewer needle pricks than it seems.
Will the antibiotics harm the new marrow?
The team chooses antibiotics with the transplant in mind and checks counts and kidneys daily. An untreated infection is a far bigger threat to the recovery than the medicines used to treat it. Ask the team if you are worried about a particular medicine.
What is the difference between a fever and sepsis?
A fever is a raised temperature. Sepsis is when the body's response to an infection starts to affect blood pressure, breathing, the kidneys or thinking. Low counts make the slide from one to the other faster, which is why a fever is acted on straight away.
Can we bring home-cooked food into the room?
Only if the unit permits it, and only under its food-safety rules. Many units allow freshly cooked, well-heated food eaten soon after cooking, and do not allow raw salads, cut fruit from outside, street food or leftovers. Ask the dietitian before bringing anything in.
Is a fungal infection the same as thrush?
Thrush is one kind of fungal infection, usually in the mouth, and is common. Mould infections of the lungs are less common but more serious. The team watches for both with examinations, blood tests and sometimes a chest scan if a fever does not settle.
How does CION help families facing a transplant?
CION's haematology team reviews the case, presents it to a tumour board and helps you reach a qualified transplant centre. We can explain what infection precautions to expect, what to ask the centre about the ward, and how to plan attendants so that a healthy person is always available.
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 — Neutropenic sepsis
- National Cancer Institute — Infection during cancer treatment
- American Cancer Society — Stem Cell Transplant for Cancer
- NHLBI — Blood and Bone Marrow Transplant
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.
Keep reading
Related pages
The Transplant Isolation Room: Daily Life InsideHow the room is set up to keep germs outEngraftment: Waiting for Counts to RecoverWhen the risk starts to fallVisitors and Attendants During Transplant AdmissionRules for the people coming inBlood counts during chemotherapyWhat the count numbers on a report mean
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