Index  ›  health  ›  Medical News Today

Breyanzi side effects: Common, serious, and how to manage them

Medical News Today Published Feb 5, 2026 Reviewed Jul 1, 2026 ✓ Reviewed by citations.press editors
Citation-ready fact
The Food and Drug Administration (FDA) has issued a boxed warning for Breyanzi, indicating three severe and potentially life-threatening reactions.
3 · severe and potentially life threatening reactions
Food and Drug Administration
View source ↗

Breyanzi is a type of cancer treatment known as CAR T-cell therapy. Common side effects include fatigue, fever, and chills. Serious side effects, such as cytokine release syndrome (CRS), are also possible.

Breyanzi treats several forms of non-Hodgkin lymphoma, such as large B-cell lymphoma (BCL) and chronic lymphocytic leukemia (CLL). articles/drugs-xdrug-form-side-effects

CAR T-cell therapy works by using a person’s own immune system to fight types of blood cancers like lymphoma and leukemia.

To make Breyanzi, doctors collect a person’s white blood cells, genetically modify them in a laboratory to recognize cancer cells, then infuse them back into the person’s body to attack the disease.

Because Breyanzi is a living drug that actively multiplies inside the body to kill cancer, it can cause a wide range of physical reactions as the immune system goes into overdrive.

This article will cover the most common side effects of Breyanzi and how to manage them, the serious risks involved, and signs that require immediate medical attention.

Going through cancer treatment is a major physical and emotional challenge, and it is completely normal to feel vulnerable or anxious about side effects.

After Breyanzi treatment, your care team will be watching you very closely, but there are also practical steps you can take to help keep yourself safe and make the process smoother.

Remember, your healthcare team is there to support you. Never hesitate to call them if something feels off. Catching side effects early is the best way to manage them.

When Breyanzi enters the body, it launches a strong attack against cancer cells, which may make people feel like they have a severe case of the flu. The most common side effects range from mild and easy to manage to serious, requiring emergency treatment.

In addition to these physical symptoms, Breyanzi can also affect the blood. A condition called cytopenia is common, which means a person has low blood cell counts. This can involve a drop in red blood cells (anemia), platelets, which help blood clot, and white blood cells, which fight infection.

Because of these low cell counts, people might notice they bruise easily, bleed longer than usual if cut, or feel very weak.

While many side effects are manageable, Breyanzi carries a boxed warning for three severe and potentially life threatening reactions. A boxed warning is the most serious warning issued by the Food and Drug Administration (FDA) about potential side effects.

CRS occurs when newly generated T cells flood the bloodstream with cytokines, chemical messengers that stimulate the immune system. This “storm” of immune activity can cause high fevers and dangerously low blood pressure. In severe cases, CRS can cause difficulty breathing and may be fatal without prompt treatment.

In clinical trials, more than half of the people treated with Breyanzi experienced some form of CRS.

Breyanzi treatment can affect the brain and nervous system, which is known as neurologic toxicity.

Symptoms can include confusion, memory loss, and difficulty speaking or slurred speech. In serious cases, people may experience tremors, seizures, or even lose consciousness. These brain-related side effects may happen around the same time as CRS or shortly after it resolves.

Breyanzi works by genetically modifying a person’s cells to fight disease. This increases the risk of developing new cancers later, including other types of blood cancer.

These “secondary malignancies” can appear weeks or years after treatment and may be life threatening. Due to this ongoing risk, a person’s healthcare team will monitor them for signs of new cancers for the rest of their life.

Because a person usually receives chemotherapy before Breyanzi to prepare their body, and because Breyanzi attacks B cells (a type of white blood cell), the immune system becomes weakened. This increases the risk of serious bacterial, viral, or fungal infections that can be life threatening.

There is also a risk of developing hypogammaglobulinemia, a condition in which the body does not make enough antibodies to fight off infections.

Reporting side effects: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Breyanzi, visit MedWatch.

People receiving Breyanzi treatment will be given a Breyanzi patient wallet card that lists specific symptoms requiring emergency care. If a person experiences the following symptoms, they must call their oncology team immediately for advice or call 911 for emergency medical help:

It is important that you tell any healthcare professional you’re receiving Breyanzi treatment, even if you’re seeing them for an unrelated issue, as this can affect how other medical treatments work.

Breyanzi is a powerful CAR T-cell therapy that uses a person’s own genetically modified T cells to destroy cancer, but this process can trigger significant side effects.

The most common physical reactions include fatigue, fever, chills, and low blood cell counts, while the most serious risks include an immune system overreaction called cytokine release syndrome (CRS) and neurological problems such as confusion or tremors.

A person must look out for warning signs like high fever or difficulty breathing. They should also stay near their treatment center for at least 2 weeks after treatment in case an emergency arises.

To discover more evidence-based information and resources for cancer, visit our dedicated hub.

Disclaimer: While Medical News Today strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.

This article was originally published by Medical News Today ↗. citations.press indexes the source-backed facts above and links to the original. Something wrong? Corrections policy · Report an error