The short answer
Imfinzi (Durvalumab) is a type of immunotherapy called an immune checkpoint inhibitor. It binds to the PD-L1 protein on some cancer cells so the cancer can no longer switch off the immune system, helping immune cells attack it. It is used to help treat lung cancer, bladder cancer, biliary tract cancer, and other cancers, and is usually given as an IV infusion. Like all cancer medicines it can cause side effects; this page explains the common ones and the warning signs to report. It is educational only and not a substitute for your care team's advice.
Imfinzi is the brand name; its generic name is durvalumab.
It is a type of immunotherapy called an immune checkpoint inhibitor — it binds to the PD-L1 protein on some cancer cells so the cancer can no longer switch off the immune system, helping immune cells attack it.
It is used to help treat lung cancer, bladder cancer, biliary tract cancer, and some other cancers.
It is usually given as an IV infusion.
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The full explanation.
A checkpoint blocker used at many points in treatment
Imfinzi is the brand name. Durvalumab is the generic name. It blocks PD-L1, a protein that tumors and nearby cells use to switch off T cells.
What sets durvalumab apart is where it sits in a plan. It is used before surgery and after it. It is used after chemotherapy and radiation have finished, to hold ground already won. It is used with chemotherapy from the start in some cancers. So the question is not only whether you are having it, but which job it is doing in your particular plan.
The approved uses
Lung cancer. With platinum chemotherapy before surgery and alone afterwards, for non-small cell lung cancer that can be removed, when tumors are 4 cm or larger or lymph nodes are involved, and there is no EGFR or ALK change. Alone, for stage III non-small cell lung cancer that cannot be removed and has not progressed after chemotherapy and radiation given together. With tremelimumab and platinum chemotherapy, for non-small cell lung cancer that has spread, without a sensitising EGFR or ALK change.
Small cell lung cancer. Alone, for limited-stage disease that has not progressed after chemotherapy and radiation given together. With etoposide and either carboplatin or cisplatin, as first treatment for extensive-stage disease.
Other cancers. With gemcitabine and cisplatin for biliary tract cancer. With tremelimumab for liver cancer that cannot be removed. With carboplatin and paclitaxel, then alone, for advanced or recurrent womb cancer that is mismatch repair deficient. With BCG for high-risk bladder cancer that has not invaded the muscle, in people who have not had BCG before. Around surgery for muscle-invasive bladder cancer, with gemcitabine and cisplatin first and durvalumab alone after the bladder is removed. With FLOT chemotherapy before and after surgery for stomach or gastro-oesophageal junction cancer.
Immune-related reactions, and when they start
Common effects include tiredness, cough, breathlessness, rash and nausea.
The reaction that shapes the safety advice is different. Releasing the immune brake can let the immune system attack normal tissue. The label reports these reactions in the lungs, bowel, liver, hormone glands, kidneys, skin, nerves, heart and muscle. They can be severe and some have been fatal. Timing is unpredictable: some start within weeks, others months in, and a few after the last dose.
Thyroid problems are among the most common. They creep up slowly as tiredness, weight change, feeling cold, or a low mood, so thyroid blood tests are usually done at intervals.
Infusion timing and what to expect on the day
Each dose runs into a vein over 60 minutes. Depending on the setting, doses come every 3 or every 4 weeks, and the amount depends partly on your body weight. Reactions during the drip are possible, so you are observed.
Keeping a symptom diary
Because these reactions can start anywhere and at any time, a short written note beats memory. Write the date something starts, how bad it is, and whether it is getting worse. Bring it to appointments.
If you see another clinician, tell them you have had a checkpoint inhibitor, even if treatment finished months ago.
When to get help sooner
- Call 911 or go to an emergency department if breathing becomes hard work at rest, you have chest pain, or a severe headache arrives with blurred or double vision or weakness on one side. Go too if a rash starts to blister or the skin peels away, or if sores appear in your mouth or eyes, and if you have a temperature of 100.4°F (38°C) or higher while also on chemotherapy, which CDC treats as a medical emergency.
- Call your care team the same day if a cough is new or worse, stools turn loose, frequent or bloody, your eyes or skin yellow, or you crash into sudden deep tiredness.
- Call your care team within a day or two if you feel cold all the time, gain or lose weight without trying, ache in new joints, or notice your muscles are weak going upstairs.
Sources
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8baba4ea-2855-42fa-9bd9-5a7548d4cec3
https://www.cancer.gov/about-cancer/treatment/drugs/durvalumab
https://www.cdc.gov/cancer-preventing-infections/patients/fever.html
Words to know
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Common questions
What is Imfinzi?
Imfinzi (Durvalumab) is a type of immunotherapy called an immune checkpoint inhibitor. It binds to the PD-L1 protein on some cancer cells so the cancer can no longer switch off the immune system, helping immune cells attack it. It is used to help treat lung cancer, bladder cancer, biliary tract cancer, and some other cancers.
How is Imfinzi given?
It is usually given as an IV infusion. It is given as an intravenous (IV) infusion — a slow drip into a vein — at a clinic or hospital, usually repeated on a schedule of cycles with rest periods in between. The exact schedule is set by your care team.
What are the common side effects of Imfinzi?
Commonly reported side effects include tiredness, cough, shortness of breath, rash, and nausea. Not everyone gets them, and many can be managed. Tell your care team about anything new or worsening.
Does Imfinzi cure cancer?
That depends on the person, the cancer type, and its stage. For some people a medicine like this can control cancer for a long time or be part of a curative plan; for others the goal is to slow the cancer or ease symptoms. Your care team can explain the goal in your situation.
Questions to ask your doctor
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Sources last checked: 2026-08-13 what this meansLast updated: 2026-08-13Next planned review: 2027-01-14
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Editorial review complete — This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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