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Rituximab infusion reactions: symptoms and what happens next | CION Cancer Clinics
Rituximab infusion reactions usually feel like sudden flu: shivering, fever, flushing, itching or a rash, sometimes a headache or feeling sick. They happen mostly during the first drip, and usually settle when the nurse pauses it and gives medicine. Throat tightness, breathlessness or feeling faint need the nurse at once. This page explains why reactions happen, what the team does, and which signs at home cannot wait. At CION Cancer Clinics, our haematology team plans myeloma and lymphoma care with you, discussed at a tumour board and explained in plain words.
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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
- What does a rituximab infusion reaction feel like?
- Which symptoms are common, and which need the nurse right away?
- What happens if you react during the infusion?
- What do families worry about, and what is actually true?
- Which words might you hear on the day?
- Who is more likely to react, and what can this page not tell you?
- Common questions about rituximab infusion reactions
The short answer
What does a rituximab infusion reaction feel like?
Most reactions feel like a sudden bout of flu: shivering, fever, a flushed face, itching or a rash, a headache or feeling sick. They happen mostly during the first drip, and the nurses watching you are expecting them.
Why the first drip is the one to watch
Rituximab is an antibody. It sticks to a marker called CD20 on B cells, the white cells that lymphoma usually grows from, and marks them for removal. When a large number of those cells are broken down at once, they release chemical messengers into the blood. Those messengers cause the shivers, the fever and the flushing. By the second and later drips there are far fewer B cells left, so reactions usually become milder or stop.
Why it is given so slowly
The first drip starts at a slow rate and is stepped up gradually while the nurse checks your pulse, blood pressure and temperature. That is why the first day often takes most of the day. It is not a sign that anything is wrong. Later drips are usually quicker.
Before the drip starts, you are usually given medicines to make a reaction less likely, often a fever medicine, an allergy tablet and sometimes a steroid. Your team decides which.Knowing what you are feeling
Which symptoms are common, and which need the nurse right away?
Tell the nurse about anything new while the drip is running. You do not have to decide yourself whether it matters.
Common and usually mild
These are the ones most people who react will notice. They usually settle once the drip is paused and medicine is given.
- Shivering, chills or a rising temperature
- Flushing, itching or a raised rash
- Headache, tiredness or feeling sick
Less common, and needing prompt attention
Press the call bell or speak up straight away if you notice any of these. The nurse will usually stop the drip first and ask questions second.
- Tightness in the throat or chest, or wheezing
- Breathlessness or a cough that starts suddenly
- Feeling faint, dizzy or very cold and clammy
Pain where the lymphoma is
Some people feel an ache in enlarged lymph nodes, the swollen glands, or in the back while the drip runs. It can be unsettling, but it is a known effect of the drug acting on the disease. Mention it anyway.
Delayed effects at home
Rarely, symptoms start after you have left. Fever, shivering or a rash that evening needs a call to your team. Blistering or peeling skin days or weeks later is uncommon but serious and needs same-day care.
Not sure whether this applies to you?
Ask an oncologistDuring the drip
What happens if you react during the infusion?
The drip is paused
The nurse stops the rituximab and keeps a plain saline drip running so the line stays open. Most mild reactions start easing soon after the pause.
Symptoms are treated
You may be given more fever or allergy medicine, oxygen if you are breathless, or a steroid. Your blood pressure and oxygen level are checked often until you are settled.
A doctor reviews you
The haematology doctor decides whether the drip can restart that day. Many people with a mild reaction do go on to finish it, at a slower rate than before.
The next drip is planned
The reaction is written in your record. Your team may change the medicines given beforehand or the speed of the next drip. Do not change any of this yourself.
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After you go home: do not wait on these
If you have trouble breathing, swelling of the lips, tongue or face, chest pain, or you collapse, call 108 or go to the nearest emergency department now. Say you had rituximab for lymphoma. The same applies to a fever with shivering, or skin that blisters or peels. Do not wait to see whether it passes overnight.
Commonly believed
What do families worry about, and what is actually true?
"If he reacted once, he is allergic and can never have it again."
Most rituximab reactions are not a true allergy. They come from the drug breaking down B cells, which is why they fade over later drips. Many people who react on the first day complete their whole course. Usually only a severe reaction leads the team to rethink.
"A reaction means the treatment is not working."
A reaction tells you nothing either way about how well the lymphoma will respond. People who react and people who do not can both do well. The response is judged later, from examination, blood tests and scans.
"She should keep quiet so she does not trouble the nurses."
This is the belief that causes the most harm. A reaction caught early is usually easy to settle. A reaction hidden until it becomes breathlessness is harder. Speaking up is what the nurses want.
"The injection under the skin never causes a reaction."
Rituximab under the skin is usually offered only once a drip has gone well. It can still cause redness, pain or swelling where it is given, and occasionally the same flu-like symptoms.
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On your treatment chart
Which words might you hear on the day?
- Infusion-related reaction
- The team's name for symptoms that start during or soon after the drip. It is graded from mild to severe.
- Premedication
- The medicines you are given before the drip to make a reaction less likely. They can make you drowsy, so do not drive home.
- Infusion rate
- How fast the drug runs into the vein. It starts slow and is raised in steps if you are well.
- Cytokine release
- The burst of chemical messengers from broken-down cells. It is the usual cause of the fever and shivering.
- Subcutaneous rituximab
- The same drug given as an injection under the skin, usually offered only after a drip has been tolerated.
Being straight with you
Who is more likely to react, and what can this page not tell you?
Reactions are more likely in people with a lot of lymphoma cells in the blood, a very large amount of disease, or heart or lung problems. Your team knows this before the first drip and may split the first dose, run it more slowly, or watch you more closely.
What to tell the team beforehand
Mention any past reaction to a drip or a blood transfusion, any heart or lung condition, and every medicine you take, including blood pressure tablets. Some teams pause a blood pressure tablet on the morning of the drip, but only your own doctor can decide that.
What this page cannot tell you
It cannot tell you whether you will react, how severe it would be, or whether a symptom you are having now is from the drug or from something else. A new fever after treatment can also mean an infection. Those questions need someone who can see you and your chart.
Bring a family member on the first day if you can. It is a long day, and the premedication can make you sleepy.Questions we are asked
Common questions about rituximab infusion reactions
How soon does a reaction usually start?
Most start during the first drip, often as the rate is being stepped up. They are less common with later drips. A few people notice shivering or fever later that evening at home. If that happens, call your treating team rather than waiting until the next appointment.
Will I definitely react on the first day?
No. Many people have no reaction at all, and the medicines given beforehand make one less likely. Your team cannot predict it for certain, which is why you are watched closely. Going in expecting a possible reaction, rather than fearing one, usually makes the day easier.
Can a reaction be dangerous?
Most are mild and settle quickly. Occasionally a reaction is severe, with low blood pressure or breathing trouble. That is the reason the first drip runs slowly with trained nurses and emergency medicines close by. Serious reactions caught early are usually brought under control.
Can I eat and drink during the drip?
Usually yes, unless you have been told otherwise. A light meal before you come in and some water during the day are generally fine. Bring something easy to eat, because the first day can be long. Ask the nurse if you are unsure about anything specific to your plan.
Should I take my usual medicines that morning?
Ask your team before the day, and bring every medicine strip with you. Blood pressure tablets in particular are sometimes paused around the drip because a reaction can lower blood pressure. Never stop or skip anything on your own. The decision belongs to the doctor who knows your full list.
Does a reaction mean the treatment that day was wasted?
No. If the drip is paused and restarted, the full planned amount is usually still given, just more slowly. If the team decides to stop for the day, they will explain how the rest will be given. A pause is a normal part of giving this drug safely.
Is it safe for me to go home the same day?
Most people do go home the same day once they are settled and checked. Do not drive yourself, because the allergy tablet can cause drowsiness. Keep your team's number and the nearest emergency department in mind for the first night, and have someone at home with you.
My father is elderly with heart trouble. Is the risk higher?
Heart and lung problems can make a reaction harder to cope with, so the team plans more carefully. That can mean a slower drip, closer monitoring or a different order of medicines. Tell the haematologist about every heart condition and tablet before the first day, so the plan fits him.
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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
- Cancer Research UK — Rituximab
- Macmillan Cancer Support — Rituximab
- National Cancer Institute — Rituximab
- Leukaemia & Lymphoma Society — Lymphoma information and support
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
Hepatitis B Reactivation Risk With RituximabThe blood test you need before the first dripLow Immunoglobulins After RituximabWhy infections can linger for months afterwardsSteroid Effects in Lymphoma RegimensThe other medicine often given around the dripLymphoma Treatment Experience and Side EffectsEvery side-effect guide for lymphoma treatment
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