Cardiotoxicity & Protecting Heart Health During Care

Some cancer treatments can affect the heart. Doctors call this cardiotoxicity. It does not happen to everyone, and it is usually not a reason to turn down treatment you need. But knowing which changes in your body matter, and telling someone early, is part of the plan.

The National Cancer Institute names these cancer treatments as ones that may cause heart problems: trastuzumab, doxorubicin, daunorubicin (Cerubidine), epirubicin (Ellence), cyclophosphamide (Neosar), and radiation therapy to the chest.

Newer treatments can also involve the heart. NCI reports that a small percentage of patients who receive immunotherapy drugs called immune checkpoint inhibitors develop inflammation of the heart muscle known as myocarditis. Cardiac effects seen with cancer treatment include high blood pressure, abnormal heart rhythms, heart failure, reduced ejection fraction, and cardiomyopathy.

NCI describes two main heart problems that can follow cancer treatment.

The first is a weakening of the heart muscle, known as congestive heart failure. People with this condition may have shortness of breath, dizziness, and swollen hands or feet.

The second is a narrowing of the arteries that supply the heart. This can cause chest pain or trouble breathing, and it is more likely after high-dose radiation to the chest.

Either problem can show up during treatment or months to years after it ends.

The National Heart, Lung, and Blood Institute lists these symptoms of heart failure. When the left side of the heart is affected: trouble breathing, cough, fatigue (extreme tiredness even after rest), general weakness, bluish color of finger and lips, sleepiness and trouble concentrating, and inability to sleep lying flat.

When the right side is affected: nausea and loss of appetite, pain in your abdomen, swelling in your ankles, feet, legs, abdomen, and the veins in your neck, needing to pee often, and weight gain.

A general sign is shortness of breath after routine activities like climbing stairs.

MedlinePlus, from the National Library of Medicine, gives this list for people managing heart failure. Call your health care provider if you have:

• Weight gain of more than 2 pounds in a day or 5 pounds in a week
• Severe fatigue, weakness, or dizziness
• More shortness of breath than usual when you do your everyday activities
• New shortness of breath when you are sitting
• A need to prop yourself up on extra pillows to breathe when lying down
• Waking 1 to 2 hours after falling asleep because you are short of breath
• Wheezing or trouble breathing
• Chest pain or pressure
• A cough that does not go away, either dry or bringing up pink, foamy spit
• Swelling in your feet, ankles, or legs
• Needing to pee often, especially at night
• Stomach pain or tenderness
• Side effects from your medicines
• A heartbeat that is very slow, very fast, or irregular

Do not wait these out to see if they settle. NHLBI puts it plainly: your symptoms may suddenly get worse, so ask when to make an office visit and when to get emergency care. Get that answer from your own team before you need it, because the threshold can differ depending on your treatment and your heart history.

MedlinePlus suggests weighing yourself every morning on the same scale when you get up, before you eat but after you use the bathroom, in similar clothing each time, and writing the number on a chart so you can track it.

It also suggests a daily check-in: whether your energy level is normal, whether everyday activities leave you more short of breath, whether clothes or shoes feel tight, whether your ankles or legs are swelling, whether you are coughing more often or your cough sounds wet, and whether you get short of breath at night or lying down.

NCI's advice for people with treatment-related heart problems is to eat a heart-healthy diet built on fruits, vegetables, whole grains, and lean proteins while keeping sodium low; reach and hold a healthy weight; exercise regularly, with your health care provider's approval; stop smoking; get enough rest; and take prescribed heart medicines exactly as directed.

Ask whether your specific drugs or radiation fields carry cardiac risk, and what monitoring is planned. NCI notes that researchers have not settled which combinations of biomarker and imaging tests should be used for which patients and when, so the schedule is a decision your team makes for your situation rather than a fixed rule.

Ask whether a cardio-oncology referral makes sense. NCI describes cardio-oncology as an emerging specialty for people who have both cancer and heart disease.

• National Cancer Institute: Late Effects of Cancer Treatment. https://www.cancer.gov/about-cancer/coping/survivorship/late-effects
• National Cancer Institute: Investigating the Cardiac Side Effects of Cancer Treatments. https://www.cancer.gov/news-events/cancer-currents-blog/2018/cancer-treatment-heart-side-effects
• National Heart, Lung, and Blood Institute: Heart Failure Symptoms. https://www.nhlbi.nih.gov/health/heart-failure/symptoms
• MedlinePlus (National Library of Medicine): Heart failure - discharge. https://medlineplus.gov/ency/patientinstructions/000114.htm

<script type="application/ld+json"> { "@context": "https://schema.org", "@type": "MedicalWebPage", "headline": "Cardiotoxicity & Protecting Heart Health During Care", "description": "An evidence-based guide to heart effects of cancer treatment, warning symptoms, and when to call your care team.", "url": "https://cancerexplained.org/side-effects/cancer-treatment-cardiotoxicity-and-reduced-heart-function", "datePublished": "2026-07-23", "dateModified": "2026-07-28", "publisher": { "@type": "Organization", "name": "Cancer Explained", "url": "https://cancerexplained.org" }, "author": { "@type": "Organization", "name": "Cancer Explained Editorial Team" }, "medicalAudience": "Patient", "aspect": "Cancer Information and Support" } </script>