Hematologist
CION Cancer Clinics
Low immunoglobulins after rituximab: what your result means | CION Cancer Clinics
Low immunoglobulins after rituximab are common. Rituximab removes B cells, the white cells that make antibodies, so antibody levels can fall and stay low for months or longer after treatment. Many people have no problems and are simply watched. Others get repeated chest, sinus or ear infections. Treatment ranges from prompt antibiotics and vaccines to antibody replacement for serious, repeated infections. This page explains the report and when to act. At CION Cancer Clinics, our haematology team plans myeloma and lymphoma care with you, discussed at a tumour board and explained in plain words.
BP
Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
17+specialists on panel
15,000+patients treated
35+centres across Telangana & AP
4.8★ / 800+Google rating
On this page
- Why are immunoglobulins low after rituximab?
- Who is more likely to have low antibody levels?
- What do the words on an immunoglobulin report mean?
- How is it checked and managed?
- What do families believe about low immunity, and what is true?
- What helps at home, and what can this page not tell you?
- Common questions about low immunoglobulins after rituximab
The short answer
Why are immunoglobulins low after rituximab?
Immunoglobulins are antibodies, the proteins your body makes to fight infection. Rituximab removes B cells, the white cells that make them, so antibody levels can fall during treatment and stay low for months or longer afterwards.
What that means in daily life
For many people, a low result causes no trouble at all and is simply watched. For others, it shows up as infections that keep coming back: chest infections, sinus infections, ear infections or infections that are slow to clear. The number on the report matters less than whether you are actually getting ill.
Low antibodies are a different problem from a low white cell count straight after chemotherapy. That count usually recovers within weeks between cycles. Antibody levels recover far more slowly, so the infection risk can outlast the treatment itself by a long way.
How long it lasts
B cells usually start to return some months after the last dose of rituximab, and antibody levels follow slowly behind. In people who have had maintenance rituximab, repeated courses, or other treatments for lymphoma, recovery often takes longer. In a smaller group, levels stay low for years.
What doctors call it
On a letter you may see hypogammaglobulinaemia. It means low antibody levels in the blood, nothing more. It is not a new cancer and it is not a sign that the lymphoma has come back.
Who is more affected
Who is more likely to have low antibody levels?
Your team keeps a closer eye on these groups, but anyone treated with rituximab can have low levels.
Maintenance rituximab
Rituximab given every few months after the main treatment keeps B cells down for longer. Antibody levels are usually checked from time to time while it continues.
Levels already low at the start
Some lymphomas and chronic lymphocytic leukaemia lower antibody levels on their own, before any treatment. Rituximab can push an already low level lower still.
Several lines of treatment
People who have had chemotherapy, repeated rituximab courses or a stem cell transplant usually take longer to rebuild their antibodies.
Also worth mentioning
- Long courses of steroids
- Older age
- Lung disease or diabetes
A history of repeated infections
If you already needed several courses of antibiotics in a year, tell your team. That pattern often matters more than any single blood result.
Not sure whether this applies to you?
Ask an oncologistOn your report
What do the words on an immunoglobulin report mean?
- IgG
- The main long-lasting antibody against bacteria and viruses. It is the level most decisions are based on.
- IgA
- The antibody that protects the lining of the nose, chest and gut.
- IgM
- The first antibody made in a new infection. It is often the first to fall after rituximab.
- Reference range
- The usual range at that laboratory. Ranges differ between labs, so compare results from the same lab over time.
- Immunoglobulin replacement
- Antibodies collected from healthy donors, given by drip or under the skin, for people with low levels and repeated serious infections.
Step by step
How is it checked and managed?
-
A baseline blood test
Many teams check antibody levels before rituximab starts, so later results have something to be compared with.
-
Checks during and after treatment
Levels are rechecked from time to time, especially during maintenance, or whenever infections keep coming back. A single low result is read alongside your symptoms and a repeat test.
-
Treating each infection promptly
The first step is usually simple: getting infections seen and treated early, rather than waiting to see whether they settle.
-
Vaccines and preventive antibiotics
Your team may suggest non-live vaccines such as flu and pneumonia, and sometimes a preventive antibiotic through the months when infections are most likely.
-
Replacement, if infections are serious
When levels are low and infections are serious or repeated despite these steps, immunoglobulin replacement may be considered. It does not suit people with low levels and no infections, and it is reviewed over time rather than given forever by default.
!
An infection that needs care today
A fever with shivering, breathlessness, chest pain on breathing, confusion, or feeling suddenly very unwell needs a doctor the same day. If breathing is difficult or the person is drowsy and hard to wake, call 108 or go to the nearest emergency department. Say they have had rituximab and may have low antibodies. Do not wait for the next clinic visit.
Leave a number, we will call you
One field. No form to fill in, and no charge for the call.
Commonly believed
What do families believe about low immunity, and what is true?
"Low immunoglobulins means the lymphoma has come back."
It does not. Low antibody levels are an expected effect of rituximab removing B cells. Whether the lymphoma is active is judged from examination, blood counts and scans, not from this test.
"Immunity tonics and supplements will raise the level."
No tonic, powder or herbal mix brings back B cells or antibodies. Some supplements interact with treatment or upset the liver. Show every product to your team before taking it.
"He must stay locked indoors until his levels are normal."
Complete isolation for months is rarely needed and harms mood and fitness. Hand washing, avoiding people who are clearly unwell, and a mask in crowded places are usually enough. Ask your team what suits your own situation.
"Every low result needs replacement drips."
Most people with low levels never need replacement. It is usually kept for low levels with repeated or serious infections. A number on its own is rarely the reason to start it.
Being straight with you
What helps at home, and what can this page not tell you?
Keep a simple diary of infections: the date, what it was, and which antibiotic was given. Bring it to every visit. That record is often more useful to your haematologist than any single antibody result.
Everyday habits that help
Wash hands before eating and after being out. Eat freshly cooked food, and drink boiled or filtered water. Keep household members up to date with their own vaccines, including the yearly flu vaccine. Get a cough that is not settling, or a fever, seen early rather than treated at home.
What this page cannot tell you
It cannot tell you whether your own level is low enough to matter, when it will recover, or whether you need replacement. It also cannot tell you whether live vaccines are safe for you yet. Those depend on your treatment history, your infections and repeat tests, and belong with your treating team.
Tell any doctor treating you for an infection that you have had rituximab. It changes how quickly they should act.Questions we are asked
Common questions about low immunoglobulins after rituximab
How long do immunoglobulins stay low after rituximab?
For many people, levels begin to recover within months of the last dose, as B cells return. After maintenance rituximab or several treatments, it often takes longer, and some people stay low for years. Only repeat blood tests over time can show which pattern you follow.
My report says IgG is low but I feel fine. What now?
A low level with no infections is usually watched, not treated. Your team will likely repeat the test and ask about any infections. Keep a note of illnesses and antibiotics in the meantime. Get any fever or chest infection seen promptly, because it may need faster treatment than before.
Can I have vaccines if my antibodies are low?
Non-live vaccines, such as flu and pneumonia vaccines, are generally allowed, though the response may be weaker after rituximab. Live vaccines are usually avoided for a period. Your team will advise on timing, because a vaccine given too soon may give little protection.
What is immunoglobulin replacement like?
It is given either as a drip in day care every few weeks or as injections under the skin, which some people learn to do at home. It is made from donated blood plasma and is carefully screened. Headache and tiredness afterwards are the most common complaints.
Is immunoglobulin replacement covered by schemes or insurance?
Coverage varies by scheme, policy and the reason it is prescribed. Aarogyasri, CGHS, ECHS, EHS, PM-JAY and cashless insurance each have their own rules, and these change. Ask the team for a written note of the indication, then check the current rules for your own cover.
Should my family avoid visiting?
No. Family who are well can visit normally. Ask anyone with a cold, fever, loose motions or chickenpox to stay away until they have recovered. Good hand washing matters more than limiting visits. Company and support are part of recovery too.
Do I need to take antibiotics all the time?
Not usually. Some people are given a preventive antibiotic or antiviral for a period, based on their treatment and history. Never start, stop or change one on your own, and do not keep leftover antibiotics at home to self-treat. Each infection should be assessed.
Does a low level affect future lymphoma treatment?
It can shape the plan. If you have had serious infections, your team may weigh whether more rituximab is needed, add extra protection, or check levels more often. It rarely rules treatment out. Ask how your antibody results are being factored in.
Your Haematologist
Meet CION's haematologist. One specialist for your blood report and your plan.
Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
Want a specific doctor for your case? Mention them when booking.
Book Free ConsultationBook an appointment with our specialist
Share your name and number — we'll call you back within 30 minutes to schedule your consultation.
Patient stories
Hear it from people we have treated
Every story is a video, in the patient's own words. Nothing here is a written testimonial.
Sources
- Cancer Research UK — Rituximab
- Macmillan Cancer Support — Rituximab
- National Cancer Institute — Rituximab
- Cancer.Net — Coping with cancer: side effects
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
Vaccination During and After Lymphoma TreatmentWhich vaccines to have, and when they workHepatitis B Reactivation Risk With RituximabAnother infection risk rituximab bringsBlood counts during chemotherapyHow white cell counts are read during treatmentLymphoma Treatment Experience and Side EffectsEvery side-effect guide for lymphoma treatment
Talk to us
Getting infection after infection since rituximab?
Tell us what has happened so far. Our haematology team will review your results and help you plan the next step. One helpline serves every CION centre.